Digital Design V12 N01 198201
Most digitizers are t pretty much alike... :the New CalComp 9000 · Series is the exception.

Most are priced alike ... ~ except the CalComp 9000.
The new CalComp 9000 Series Digitizer gives you the best performance " features at the lowest price. Only the .. new CalComp 9000 allows you to customize application configurations by ~ switch selectable character framing, ~ data rate, operating modes and interfaces.
Most have the same features ... · except the CalComp 9000.
<' Check the specs and you will find that · accuracy, resolution, digitizing sur-
face sizes and even transducers are just about the same on most competitive models.

Then consider these CalComp digitizer features: You can choose a digitizing surface and transducer to fit your application. Solid or backlighted surfaces are available in sizes from 12" x 12" to 60" x 44". All have standard accuracy of ±0.0105 inch and resolution of 1000 lines per inch. Transducer choices include a pen stylus, and 4, 12 or 16-button cursors.
The compatible 9000 Series lets you communicate simultaneously with several host computers and/or peripherals via multiple interfaces.
And, you can count on CalComp to keep your digitizer operating at peak efficiency. Each CalComp 9000 Series Digitizer carries a full one-year

warranty on parts and labor. Reliable, nationwide direct sales and service guarantee quick response time.
The new CalComp 9000 Series is an exceptional digitizer. Point for point, when it comes to price and performance, CalComp is the choice.
Call or write today for complete specs on the 9000 Series.
A Sanders Grapt11cs Company
California Computer Products, Inc. 2411 West La Palma Avenue Anaheim, California 92801 Telephone (714) 821·2011

Circle 5 on Reader Inquiry Card


"High Performance


At A Low Price"

Plug compatibility. That's what the ZENDEX Line offers you. Any board or software that works on your lnte12 lntellec2 System will also work in the ZENDEX Model 835. That includes ISIS-11 Single or Double Density, In-Circuit-Emulators, and Universal PROM Programmers. The Model 835 System includes a cabinet with two Shugart SA801 R Drives, and a CPU cabinet that utilizes the powerful ZX-85 SBC CPU, ZX-200A MMFM & FM Diskette Controller, and parallel 10 Interfaces for CRT, TTY, LPT & UPP. CP/M3 Operating Systems included.

Licenses to run Intel Software on ZENDEX products must be obtained from Intel Corp.

1 - TM ZENDEX Corp. 2 - TM INTEL Corp. 3 - TM Dig ital Reaearch


6644 Sierra Lane, Dublln, Callfornla 94566

Tel.: 1415) 828-3000 TWX 910 389 4009

Z e n d e , x®In England call Giltspur Microprocessor Systems 74176 Northbrook Street


Newbury, Berkshire RG13 1AE Tel. : Newbury (0635) 45406 TWX 848507

Circle 6 on Reader Inquiry Card

~11 us your thoughts Digital Design is your forum - your inputs help keep the magazine interesting and vital to the design community. So let us know how we're doing and how we can serve you better in the future. We want to know what you like or dislike about Digital Design, the subjects you'd like to see us address, how you feel about the problems you face every day as design professionals.
If you have thoughts your peers should know about, put them in a letter in Digital Design. Have your say in your magazine! Send letters and comments to: Editor, Digital Design, 1050 Commonwealth Ave., Boston, MA 02215.

2 Digital Design JANUARY 1982


Jeffrey C. Hoopes


Paul Snigier

Technical Editor

Dave Wilson

Managing Editor

Bob Hirshon

West Coast Technical Editor Bill Groves

East Coast Technical Editor

Nicolas Mokhoff

New Products & Directory Editor

Martha Hawkins

International Electronics Editor

Ron Neale

International Computers Editor

Eric Wignall

Art Director

Richard Sarno

Assistant Art Director

Josh Randall

Staff Artists

Jacky Brill, Laurie R. Guptill


Donni Richman

Production Manager

Erik W. Slickman


Noel J. Boulanger Jon Buchbinder, Amy Gerber
Joan Scheffler

Marketing Services Manager

C. King

Circulation Elizabeth Mahon-Laidlaw, Mgr. Sarah Binder, Regina Harrington Lynda Neue, Jennifer Wood


Don Spencer, Mgr.

Lorraine Cooley, Yva Doricent

Judy Lungelow, Debbie O 'Connell

General Administration Karen Melanson, Mal Rankin

Publication Development H.G. Buchbinder

Group Publishing Director


Albert J. Forman


DIGITAL DESIGN is circulated only to qualified research, development and design engineers in all branches of industry, government institutions and universities. To obtain a complimentary subscription , request (on company letterhead) a qualification card from Circulation Director. For change of address, attach old address label from recent issue to new company letterhead or note. Send this plus request for new qualification card to :

Circulation Departmen


1050 Commonwealth Ave.

Boston, MA02215

Subscription rates: non-qualified subscribers (US and Canada) - $35/ yr.; non-qualified foreign -


surface mail - $45; air mail - $70.

DIGITAL DESIGN solicits editorial material and


articles from engineers and scientists. Contributors

should submit duplicate manuscripts typed with two

spaces between lines. All illustrations should be clear ; components on all schematics and line draw-

ings should be labeled. The editors assume no re-

sponsibility for the safety or return


of any unsolicited manuscripts.

Published monthly by Morgan-Grampian Publishing Company, Domenic A. Mucchetti, President; Executive, Editorial and Subscription Offices, 1050 Commonwealth Ave., Boston, MA 02215. Telephone: (617) 232-5470.
Morgan-Grampian also publishes American City & County · Circuits Manufacturing · Contractor · Design Engineering · Electronics Test· Industrial Distribution · Industrial Product Bulletin · Mart · Municipal Index


With LSI 11/PDP 11 Software Compatible DiscfTape Con· trollers Offering Single Board Low Power µP Based
.. Design and Low Cost ... Plus Many Other Good Reasons! The reasons start with DI LOG'S (Distributed Logic Corp's.) full time engineering and design staff. Not outside suppliers. That means when you contact DILOG
.. for product selection or after sale service, you 'll get "first hand'' assistance ...along with years of experience manufacturing µP based controllers that interface with DEC11 CPUs. The intelligent products you 'll discuss all utilize common proprietary architecture and DILOG automated design techniques-products with exceptional reliability and cost efficiency ... mostly available from stock. And

when you plug a DILOG controller into your DEC CPU it's ready-to-run because it's fully operating system software compatible.
These high performance data storage interface products also feature· minimum bus/space requirements· up to 60% less power· 10 to 50% lower cost · automa11v self-test ... and numerous other features for easy system integration.
Consult the DI LOG/disc-tape compatibility table for your needs. Then ask for detailed data on existing, or future products from DILOG .. .#1 in single board DEC 11 compatible disc/tape controllers.Distributed Logic Corp., 12800-G Garden Grove Blvd. ,·Garden Grove, CA 92643, Phone: (714) 534-8950 · 64-A White Street, Red Bank, New Jersey 07701 Phone: (201) 530-0044









WINCHESTER 5~ ·, 8" OR 14"













·Trademark Digital Equipment Corp.

Circle 13 on Reader Inquiry Card
JANUARY 1982 Digital Design 3

. Compatible Computer Directory

by Paul Snigier, Editor

This year Digital Design is providing something extra: a 13th issue dated October 15, 1982 that will be a comprehensive

computer compatible directory. It will be our third directory of this type. The previous two - published in January and

August/September 1981 - were extremely well-received by our readers.

Like its predecessors, this third directory is designed to meet your needs as well as those of OEM integrators and system

designers. Searching for compatible memory and peripherals for manufacturers' computers can be a hassle. Where do you

look? We understand that many system designers scan through publications, and some save back issues or tear out ads. Since

most major manufacturers of compatible computer boards and periphera"Is advertise in Digital Design often, at least once each


six months, this is a workable solution. However, we want to do more for you and publish compatible computer equipment

directories and listings of firms that manufacture/service compatible memory and peripherals.

Compatible computer manufacturers' responses to our questionnaires were more than we expected: they were over-

whelming! In addition, there was strong, favorable reader response. Many called or wrote to say that the time had come for

such a directory.

Because of such favorable response, we will expand the directory. We will publish descriptions of new devices that will have

been introduced by then and will include those manufacturers who missed last August's questionnaire . If you were left out and

want to be listed in the expanded directory, then please fill out this questionnaire. Use photocopied forms for each product.

Don ·t take the easy way out and write: "'See spec sheet. ·· (We cannot reprint spec sheets.) Include in your mail-back, press

releases, photos, manuals, literature, articles, etc . Also, let us know whom to contact for more information.

Remember, if your firm manufactures compatible computer products, this is an excellent opportunity to be listed in a

directory that will reach 60,000 direct (159,000 total) readers - leading computer system integrators throughout the industry.

This directory issue will be saved by system integrators and designers, and will be actively referred to over the next 12 months

and beyond.


I If your firm manufactures compatible memories, peripherals or equipment for DEC, Data General and other manufacturers,

then let our 60,000 direct (159,000 total) readers know . Send us all the product literature you ·ve got. Please place one
I product per page (make photocopies as desired) . Give brief description and important specs. Please do not write: ··see Spec


I Sheet.·· (We cannot reprint spec sheets.) All product information must be in before August 13, 1982.

: Category (for this product)

O Magnetic Media Drive
I 0 Add-In/Add-On Memory I O Communications I O Array Processor
O Display Terminal

D Printers and Plotters D Interface Board (Controllers,
Converters, Special 1/0, etc)
D Test Equipment/

D Power Supplies/UPS/Line
D Packaging, Hardware,
Backplanes, Enclosures
D Services


O Other(describe) - - -- - - - - - - - - - - - - - - - -


Product Name/Model No. - -- -- - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - Description/specs _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __

This product is compatible with? _ _DEC, _ _ DG, _ _P-E, __HP, _ _Intel, _ _ _ _Other Price(s) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
Do you O manufacture? D wholesale? D service? D other? describe - - - - - - - - - - - - - - - - - - - - - -


Check type(s) of maintenance available:

_ _ Return to factory (RTF)

_ _ Third party service (3rd P)

_ _ Qther? describe - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - Number of your field offices: _ _FO.

Companycontact(sales) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ _ _ _ __ Company Name/Division_ _ __ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ __

Street/Box# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - City_ _ _ _ _ _ __ _ _ __ ___State/Zip_ _ _ _ _ Phone (
Whom should our editors contact? _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ __

Mail this form to Directory Editor, Digital Design, 1050 Commonwealth Ave . , Boston. MA 02215 (617J 232-5470

4 Digital Design JANUARY 1982

2159 Bering Drive, San Jose, California 95131 (408) 263-9920 TWX 910-338-2145 Circle 4 on Reader Inquiry Card

- Technology Trends-

Public And Private Demand For Data Security Increases

The rapidly increasing role of computers is making a growing volume of data on individuals and businesses available to an expanding number of people. Behind the familiar CRT terminals in banks, airline ticket reservation counters, hospitals and places of employment, computers store data bases that often contain private or sensitive personal or business information.
There is a growing need for security to provide privacy for this confidential data . Public awareness of this problem is creating a concern over the need for adequate safeguards to ensure that information given in confidence will remain confidential . In addition to general public concern , business management is becoming increasingly interested in ensuring that adequate data security measures protect sensitive financial information from unauthorized access .
The widespread use of terminals to access data dictates some kind of atthe-terminal security system . Such systems have traditionally suffered from being too costly or in the interest of cost effectiveness, supplying too little security.
One solution to the problem comes from TEC. They combine their model 630 video terminal with a magnetic stripe reader designed to read the IATA (International Air Transport Association) track of standard magnetic stripes found on bank cards. In operation , users simply pass a card with a magnetic stripe containing a security code through the reader. The µ,P in the 630 then calculates parity and performs a CRC check on the data without displaying the security code. After the magnetic stripe data is accepted by the terminal, the security code can be used by the computer system to ensure that the operator is authorized to access the data base. Since the IATA track contains 60 alphanumeric characters , there is plenty of room to accommodate even the most complex security codes.
The magnetic stripe system solves many of the problems associated with other security systems . The most com-
6 Digital Design JANUARY 1982

mon problem associated with systems that key in passwords from a terminal , for example. is that in order to convey sufficient information. passwords must be too long to memorize. In practice. terminal operators typically write the password down on a piece of paper, and copy it into the terminal. with possible onlookers around . Also. all too often. the piece of paper containing the password is lost - sometimes to be found by unauthorized personnel who can then access , and possibly alter, a previously secure data base .
Other traditional security systems often fail to provide the level of security desired by their users. Some systems restrict sensitive information to specific terminals that are usually in the office.

or under the supervision of authorized personnel. However, these systems are
vulnerable to a breach of security be- ....
cause unauthorized employees may gain the use of these terminals when authorized personnel are absent during breaks or after normal working hours. Protecting terminals with a lock and key has proven to be less desirable from a security standpoint. All too frequently. keys to " secure" terminals are left in unlocked desk drawers .
Unlike keys or strips of paper. terminal security systems based on mag-
netic stripe readers can offer many of ·
the advantages of credit cards. Like a credit card, the plastic cards containing the magnetic stripe can be impressed with unique numbers . If such a card is

Tee's Model 630 video terminal integrates a magnetic stripe reader allowing only authorized personnel to access the data base.



Now, from the memory lead·, you can pt 32 MB of
bip-perfOl'llUIMe 1D1111orJ in a compact 15%" system.

applications - anywhere microsecond speed, megabyte main memory or peripheral memory is required. Our l~page BULK MEMORY brochure will tell you more. And you can have it at no charge by completing the COl.lpon
below, or calling us at 609-799-0071.
DEC ad MULTIBUS_.......,.....,....olDialtal ......-~ md lllUI Corponliaa. ....,..sMlly.

·--------------- :



D Send me your 16-page brochure detailing BULK SEMI.




_ _ _ _ _ _ _ _ _T i t l e - - - - - - - I

Technology Trends
lost or stolen, its number can be flagged on the computer data base as invalidimmediately disabling the card's authorization code and protecting the data base from being accessed with a stolen card.
Security measures can be extended a step futher using the card system. Computer authorization cards can be integrated with employee identification cards. If employees are required to show such cards when entering the plant, it is unlikely that the loss of a card would go unnoticed for more than one working day. Such a system can prevent long time lapses between the loss of an authorization code and detection of the loss. If lost, unrecorded strips of paper, or even keys to locked terminals , could go unnoticed for long periods of time , especially if the employee who lost them had no need to access the computer for several days.
In use , the card-based security system offers great flexibility . Employing an authorization hierarchy, a company can control levels of data availability. At the lowest level. only that information that is of immediate use in a particular task would be available to an employee; at the highest level , top management could have access to all data. Between these two extremes , authorization levels could be set to allow just the necessary information availability according to the need to know at each level.
Besides overall hierarchical security, the card-based system can provide specialized security. Consider the case of a manufacturing organization's bill of materials program, for example. There may be 50 employees in the manufacturing organization who need to access the bill of materials program. to obtain part and lot numbers to perform their job functions . However, of those 50 employees. perhaps five are properly authorized to alter the bill of materials program - to order new parts. or delete obsolete part numbers. for example. By providing two types of security codes on cards, read only and read/write, the company can allow all necessary access of the data base for efficient work flow. yet still restrict the ability to alter the data base to those five employees who have been issued cards with the read/write authorization code .
The card-based security system can be as beneficial for individual privacy as for the corporate environment. Con-

sider the case of a hospital , for ex- modations. tests. the number of staff in

ample. With proper construction of the the operating room. and type of insur-

patient data base, hospital computer ance. Although the security afforded in

authorization codes can be developed this hospital situation is but a single

to ensure that only relevant data is example. parallel privacy could be

available to various hospital staff. The easily obtained for other data bases

patient's doctor, and the nursing staff, such as those in banks and at the IRS.

· for example, might be able to access all

As the use of computer terminals for

medical information on the patient. The data base access grows, there will be a

hospital administration and accounting corresponding demand for satisfactory

staff, on the other hand , might be able security for personal and business data.

to access only the information related to This will create an ever-growing mar-

calculating the patient's bill: duration ket for cost-effective versatile terminal-

of stay in the hospital, type of accom- based security systems.

µ,Ps Influence Printer

Reliability, Cost and Features


The development of µ.Ps continues to ties, block printed letters , multiple

influence the design of electronic print- fonts , and features such as proportional ·
ing devices according to 0. Ralph spacing and right-justification . These

Finley , vice president of Dataquest types of features are now easier to

(Cupertino, CA) and Director of the design into printers due to the use of

Electronic Printer Industry Service.

µ.Ps and their associated software.

As a result of the growing demand

In an exciting new class of printers,

for printed information and the supply that of intelligent page printers such as

of increasingly cost-effective printers, the Xerox 9700, µ.Ps provide the abil-
.. the printer market has grown rapidly in ity to print forms along with data . This

the last ten years, with the number of ability is extended to the use of com-

printers in use in the United States pany logos, the ability to shade areas to

growing from about250,000 in 1971 to highlight information, and the ability to

about 3.5 million in 1981. Strong actually sign computer letters with

future growth, to about 11 .6 million , is good representations of signatures.

expected by 1986. Despite the increas-

During the 1980s, expect continued

ing proportion of small printers , often strong-but-slowing growth in the tradi-

sold at prices affordable by average tional products sold for DP and WP

consumers, the revenues have grown users , i.e., impact line printers and

from about $600 million in 1971 to dai sywheel printers . Two areas, how-

nearly $5 billion in 1981 , and are ever, should see exciting growth -

expected to exceed $14 billion in 1986. shared-application printers that will dis-

The most recent influence of µ.Ps place a combination of devices includ-

has been the addition of features on ing photocopiers. facsimile machines.

electronic printers . As an example, dot offset duplicators and traditional printers:

matrix printers are now capable of and very low cost printers for use with

printing more than simple 96-character personal computers that are starting to

fonts. They offer full graphics capabili- invade the consumer market.


Digital Announces

Performance Service for PDP-llS


A new computer system performance SPM-1 lM , is an event-driven data
service helps users optimize operation collection and reduction instrument ·

of PDP-11 computers running under the that monitors hardware and software

.. RSX-llM operating system . Desig- resources including the CPU. memory ,
nated CPS-1 lM , it includes license and 1/0 and storage devices, file system,

installation of performance measure- and task loader. Collected data are used

ment software and on-site training and to analyze resource use at total system,

support by a DEC software specialist. collective and individual task levels.

Price of the service is $9370.

The monitor aids location of bottle-

The software performance monitor, necks. performance analysis of appli-

8 Digital Design JANUARY 1982

Electronics & Electrical Products

Circle 12 on Reader Inquiry Card


IEEE $55 APPLE INTERFACE & CABLE $90. RS-232 $70, TRS-80 CABLE $35.


NEC 7710 and 7730 Spinwriter .

. . $2345.00

NEC JB 1201 M 12" Manitar . Okidata Micraline-80 Okidata Micraline-82A . Okidata Micraline-83A .. . .......... . Diabla 630 .

159.00 379.00 499.00 729.00 1995.00

Televidea 912C Televidea 920C

669.00 729.00

Televidea 950 ..


CBM 8032 Computer .. . .... . ..... . 1149.00

CBM 8050 Disk Drive .. .


CBM VIC-20 . .


Amdek lOOG ...... . ........... .


Amdek Color - 1 13 " Monitor ........ . 329.00

Qume Sprint 9/45 (Full Panel) .


Atari 400 16K ....... . .. .


Atari 825 Printer ...


Atari 850 Interface . Atari 810 Disk Drive . Atari 800 16K . . ...... . .·....·....

139.00 449.00 749.00

Epson NIX-70 Epson NIX-80 ...... . . . . . .. . ..... . . Epson NIX-80 FT .. . Epson NIX-100 FT .

349.00 449.00 549.00 729.00


WEST COAST 1-800-235-3581
3533 Old Conejo Rd . #102 Newbury Park, CA 91320
1-805-499-3678 CA. TOLL FREE 1-800-322-1873

EAST COAST 1-800-556-7586
12 Meeting St.
Cumberland, RI 02864

We Accept C.O.D .'s ·Stock Shipments Same Day ar Next · No Surcharge for Credit Cards · All Equipment Factory Fresh w/MFT Warranty· We Carry the Complete Line af Personal Software · Prices do not Reflect Shipping Charges Sales Tax Where Applicale

Circle 19 on Reader Inquiry Card 10 Digital Design JANUARY 1982

Technology Trends
cation programs, measurement of workload trends for planning system expansion, and system tuning for improved perfonnance.
SPM-1 lM software is a low-overhead , event-driven monitor capable of high resolution ( 10 µ.sec clock) and flexible application. The monitor pennits both overall RSX-llM system evaluation and isolation of particular subsystems or application programs by allowing the user to select either continuous or sample monitoring as well as specific tasks and resources for data collection . Likewise, perfonnance reports can be generated to show either the effects of total system workload or the impact of individual tasks and runs.
Dermot Bredin, computer perfonnance services manager for DECs

Software Services Group , said that the CPS-.1lM service is designed to meet a real and significant business need: to
make opti~um use of computer sys-
tems and staff. "Computer systems are corporate resources. and system performance can impact many levels of company activity , " Bredin said. " It has a direct bearing on programmer productivity and on the level of service a computing facility provides to its users .
"With the monitoring capability of SPM-1 lM, system managers can pinpoint existing problems with overloaded resources and prevent new ones from developing ," he said. "They can improve the job mix and reduce the waiting time for resource usage, thereby improving response time for users. System planners can also measure the
growth of workloads and gauge the true ,..
capacity of the system , and that helps financial managers to plan capital
. investments for system expansion more
accurately.' '


Memory Technology To Experience Transitions

Progress in silicon device complexity ment of rigid disk systems involving

for the 1980s will continue at a fast pace integrated film heads. multiple heads

according to a 1200 pg . study by per disk surface. high efficiency coding

Mackintosh International. MOS schemes and the widespread acceptance

DRAMs will be four times more ad- of high coercivity plated medium.

vantageous than SRAMs, and the use Following recent trends. there will be a

of CMOS technology to implement continuation of the emphasis on fixed.

SRAM memory devices will increase. non-exchangeable disk systems based

Bipolar technologies will continue to on Winchester. MiniWinchester and

be extensively used for high speed MicroWinchester technologies .

memory devices with the newer gallium

Dramatic developments will occur in

arsenide technologies providing faster floppy disk technology with the intro-

devices with lower power dissipation. duction of buried servo-on-track tech-

Josephson Junction technology will niques. improved media and heads.

. provide even faster speeds. but is con- Orders-of-magnitude increases in track . sidered unlikely to find wide use in and bit-density will be achieved by the
commercial applications because of the end of the 1980s. Extensions of the

inconvenience of the liquid helium current range of products to provide
· environment required. Gallium arsenide cost-effective mini and micro disk
. memories operating at liquid nitrogen backup storage for many consumer and
temperature are expected to provide office product applications will be a

comparable speed and power dissipation. feature of this decade.

Despite the withdrawal of three

.. Magnetic tape will increasingly be

companies from the magnetic bubble used to provide backup archival storage

.. business. it is expected that the devel- to non-exchangeable disk systems and

opment of the technology will continue this ·will be primarily based on the

with magnetic bubble devices having a streaming tape concept with new. high

factor-of-four packing density advan- performance cartridge products being

tage over semiconductor devices. For introduced.

those applications requiring non-volatile

.. The development and introduction

storage and high reliability. magnetic by 1990 of storage systems using per-

bubbles will provide ideal solutions.

pendicular (vertical) recording will

Continued development of magnetic achieve a factor-of-ten increase in

recording will lead to further develop- storage density compared to normal in-

plane recording.

The main growth of memory usage

in the consumer sector will be associ-

ated with the increase in shipments and

use of low-cost personal computers. In

the business computer sector. increas-

ing computer shipments. particularly in

the lower cost systems range. and

memory usage will accelerate as

memory prices continue to fall.


Memories in the computer peripheral sector are primarily associated with the

many types of terminals and. to a lesser

extent. with controllers for printers.

disk and tape systems . The development

of low-cost terminals and their penetra-

tion into the domestic and business

environment will expand and create

new market opportunities for electronic ·

and electromechanical memories.

New facilities and services being

offered in the telecommunication
· sector will provide opportunities for the

memory vendors: an increasing quantity

of high speed memories will be re-

quired to handle the burgeoning elec-

tronic mail traffic and to provide the

data base storage for public information

and transaction services .

In the office equipment sector. WPs

· will continue to provide expanding
opportunities for the memory suppliers.

The consultants also predict that the

development of intelligent. electronics-

based collating copiers will also pro-

vide a large opportunity for memories.

Of significance is the dramatic increase

in memory requirement that will

accompany the provision of facilities

for the manipulation. transmission and

processing of graphics . Such facilities

will be found in electronic mail. elec-

tronic document storage and in inte-

grated information systems .

Worldwide shipments of electronic

memory bits will grow from $4 billion

in 1980 to more than $50 billion in

1990. The market for magnetic bubbles

will consistently remain at l % of the

total solid state memory market.

Worldwide markets of electro-

mechanical memories (OEM values)

will increase from $5 billion in 1980 to

more than $60 billion in 1990. In value

terms. floppy disk memory shipments

will exceed those of rigid disk systems

with major new opportunities for floppy

disks occurring in the consumer and

office products sectors . Mackintosh

al so predicts that there will be signifi-

cant shipments of optical disk systems

from 1985 onward. Want more infor-

mation? Contact: Yves G. Blanchard.

Director of Marketing. Mackintosh

Consultants. Inc .. 244.4 Moorpark

Avenue. Suite2l l. San Jose. CA 95128. your
PDPll Unibus·
with the
push of
a button.

Do you need to share peripherals? Do you have multiple cpu's with a limited number ofperipherals? Do you need to selectively choose which peripheral is on the bus?

If so, Datafusion Corporation's OSRll-A Busrouter can help. It is a
passive, manually operated device to perform the physical and electrical switching of the Unibus1' for PDPl 1series computer systems: up to eight switching planes (i.e., configurations}; electromechanical switching relays (simple, high reliability, minimal electrical loading}.

Essentially, each Busrouter switching plane can be viewed as a single pole, multiple throw switch.
The application shown here is a situation opposite the first, where one peripheral bus can be switched between two cpu's with the cpu not selected being terminated.

BUS1 --Q..._
'---CPU BUS2--0

CPU1 -

--ii,__--< i..._




' ' ' ' ' ' '

Many more configurations are available such as sharing multiple peripheral de vices between multiple cpu's and then selectively choosing to switch each one or all to one cpu or another.
Other PDPll products available are a bus repeater, bus cable tester, and an associative processor for high speed text search a hardware approach.
I i i We also have some ideas for the application of our products which
might not have occurred to you. If you can't get the performance that
you would like from your PDPll system, maybe we can help. Please telephone our Marketing Manager at -
(213) 887-9523 or write to Datafusion Corporation, 5115 Douglas Fir Road , Calabasas, California 91302 .


Circle 14 on Reader Inquiry Card
JANUARY 1982 Digital Design 11



a listing o


seTVJ· ces

_ pri·ce

'H Directory marks

first: it is the lar

r:ertainly the first eve

d by any publica

in the trade press.

FORTH provides advantages few other languages can offer; and

stated in our May 1981 article, " FORTH: Exaggeration Or Panacea?"

Snigier, pp. 52-57): "FORTH provides a general, compact and pow

core of constructs for arithmetic, logic, data structures, mass sto


embly. It offers

· ility to your spe

/ti-level progra elopment simpli

ctivity, hand



12 Digital Design JANUARY 1982


including print formatting. enhanced

high-resolution graphics. and ex-

tended. high-speed mathematical func-


.. tions. Over 300 operators available to
the user. Extensive. optionally loadable utilities include Diagnostics. Text Editor and Mini-Assembler. System software diskettes. Auxiliary Processor

Card and 160-page User's Manual

From A toZ

comprise the complete package. Unit price (complete system). $495; manual only (deductible). $35.

Janet Carmody Applied Analytics Inc.

8910 Brookridge Drive, Suite 300,

Upper Marlboro, MD 20870 Circle 211


Floating Point Package Utility

8080/Z80 fig-FORTH for CP/M The fig-FORTH model in machine


readable format. This package contains

two 8" diskettes. The first diskette

An options package providing a com- contains 8080 and enhanced Z80 plete fast floating point package is source code that is readable and execu-


available. Support for the STD-BUS table on Digital Research CP/M or

ZFORTH for CP/M 8" Floppy

ATC-MATH coprocessor hardware or Cromemco COOS operating systems.

FORTH for CP/M Ver. 2.2 and MP/M a Software Floating Point Package with The 2nd diskette contains FORTH

l. l. A unique dictionary lookup rou- our hardware is available. Pricing starts readable screens including a full screen tine provides an average of 2. I probes at $150 for software without hardware; editor originally published in FORTH


for a fail and l. 8 probes for a successful software and hardware. $850.

DIMENSlONS. The entire work is

find of a word in one vocabulary. Loading times are much faster than

Speech Utility

donated to the public domain in the
· manner and spirit of the original work

threaded dictionaries. Good speed Software Utility provides a text-to- -upon which it is based. Copies may be

improvement is realized while retain- speech routine to support the STD Bus. made and distributed when proper

ing FIG standard (except Dictionary ATC-Speech hardware device utilizing notice is included. Price. $25.

Structure). String Editor provided. the Votrax SCOl. Requires ZFORTH Dennis Lee Wilson

Unit price. $350.
FORTH for MDX STD Bus Same as above for FLPDOS 8" Floppy

language . Unit price. $575.
FORTH Software for TRS-80 FORTH for TRS-80 provides as stan-

Aristotelian Logicians 2631 East Pinchot Ave. Phoenix, AZ 85016

Circle 212


Media. $350.

dard a Z80 FORTH Assembler. Floating Point Package and Line Editor AYDOS Disk Operating System


ZFORTH/Plotting Package Utility (String Editor Listing provided). Sup- An implementation of the FORTH

This plotting package for Tektronics plied on 5lf.i'' floppy. requires TRS language on the Aydin 5216 color

graphics terminals provides simple Model [ & 32K memory . Options in- graphics computer. Aydos is a usercommands for plotting two arrays. clude phoneme assembler for voice oriented programming language and Commands such as AXIS. GRID. synthesis and data base utility. Unit operating system . lt is a stand-alone


TITLE CURVE. PLOT. XLABEL. price. $129.95.

software product designed for fully

YLABEL and ENDPL give the user a Norm McCollough

interactive graphics program devel-

very versatile package for generating Advanced Technology Corp.

opment and testing. and is a multi-

plotted hardcopy data from two arrays. P.O. Box 726

level. multi-user system. The user can

Unit price. $250. Dynamic Data Base Utility

Clinton. TN 37716

Circle 210 program in the higher level Aydos

language. or. where the requirement

microSPEED Language System for improved performance requires,

The Dynamic Data Base is an options The microSPEED Language System (a can operate at a macro assembler

package for ZFORTH providing a Data hardware-assisted superset of FORTH) level. Aydos 50 is a disk based system

Description Language (DDL). yielding employs an interactive compiler and consisting of an Operating System.

an efficient report writer with output the AM95 l I Arithmetic Processor to Assembler. Compiler. Interpreters. formatting and auto headings. Keys are provide increased performance for the Editor. Virtual Utilization Memory.


maintained in AVL trees with data stor- Apple 11. II+ and Hl. Features order- Debug facilities. File Management and age space automatically recovered on of-magnitude speed improvement and Device Drivers. Aydos IO is a PROM

record deletion. Blank compression is greatly enhanced programming facili- resident system without disk handling.

automatic. Unit price , $175.

ties beyond those ofBASlC and Pascal. Editor and File Management.

14 Digital Design JANUARY 1982


AYGRAPH 20 and 30

object code and misc . programs in fig- control and error checking is provided.

FORTH based. 2D and 3D graphics FORTH screen format. Price. $50.

Unit price is approximately $1075.

packages used with Aydin 5216 graph- CMOSOFT

Mr. C. Holland

ics computer. Unit price is $2500 and P.O. Box 44037 $3500. with significant qty discounts. Sylmar, CA 91342

., Datatrak Ltd.
Circle 215 Computer Centre, Bugbrooke Road,

J. Taylor Aydin Controls 414 Commerce Dr. Ft. Washington, PA 19034 Circle 213

FORTH for Compucolor
This version of figFORTH for Compucolor is available on 5.25" floppy disk. with documentation . Unit price is $79;

Gayton Northampton NN7 3EU UK

Circle 219

each additional copy is $69 .

ROMable fig-FORTH on diskette for

fig FORTH for Ohio Scientific Full fi gFORTH for Ohio Scientific


P.O. Box 6733, Station J

Ottawa, Ontario

Canada K2A 3H2

Circle 216

LSI-11/PDP-l 1. MC68000. 8080/Z80; 68K-FORTH incl. Screen-Editor. Assembler. Diskettes available in CP/M or DEC-format. Stand alone FORTH for LSI- I I. Unit price approx . $200.

6502 computers . Runs under OS-65D FORTH Application Software

Datentec Kukulies

with full FORTH disk handlers. Comes with full screen editor. lots of utilities . Runs in 20K to 32K. 811 or 514" diskettes

Cursor editors: all normal and special functions . Implementation for a wide range of terminals. Protocol emulators:

Heinrichsallee 35 Aachen, 5100 W. Germany

Circle 220

- specify when ordering. Unit price. different protocols (3270 a.o.). Advanced

$875 ; quantity price. up to 60% off. Blue Sky Products

programmable controllers: user speci- D-FORTH for the ACS-12, -14 fied application languages and multi- Developed as an enhanced version of



tasking systems. Special debuggers . the FORTH language. D-FORTH is a

729 E Willow Signal Hill, CA 90806

Johan Norberg Circle 214 Combinator Microcomputer
Applications (COMMIC)

ROM-based. high-level. interactive.
.. fully-mnemonic language operating
system. D-FORTH is user-configurable

Birger Jarlsgatan 97, S-113 56

and generates ROMable code more

Stockholm, Sweden

Circle 217 compact than assembler. Unit price is

$ I00 for the 4 Kbyte kernel.

Findcalls and Decompiler

D-FORTH-09 for ACS-09

8080 figFORTH

These fig-FORTH compatible routines A stack-oriented programming language

811 disk contains source and object as will determine what words call any ideally suited for controller and

published by Forth Interest Group. other word. Now you can eliminate development applications . Generates

Price. $50.

words which are not used. or combine ROMable code with user control of

1802 Crossassembler

words which are called by only one or interrupt. Developed in cooperation two other words; fig-FORTH decom- with Nortek. Inc. D-FORTH-09 is also

811 disk contains object and user manual piler included. Sample printout on marketed under the name SPICE

.. on disk compiled from C source files. request. Available in 9+ screens: (Stack-oriented Procedural Interactive

Price. $25 .

listing and manual alone. $25; on disk Computer Environment). The initial 4-

6800 Crossassembler 811 di sk contains object and user manual on disk compiled from C source files .

(5" Apple and 811 sssd)-$35.

R. E. Curry & Associates

P.O. Box 11428 Palo Alto, CA 94306

Circle 218

Kbyte kernel comprises a complete operating system. which includes keyboard interpreter. high-level compiler. debug facilities. and full


Price. $25.

dictionary extension capabilities . The

1802 figFORTH

4-Kbyte extension PROM contains ·

811 disk; load with RCA CDOS and 32K RAM and UART board; disk contains source and object. Price. $50.


enhanced word-vocabulary. including tools to facilitate software development.
and to provide advanced data structure ·
capabilities . Extension also includes

1802 figFORTH

Unit is a low cost. async in. async out. the ROM driver and software module

811 disk; load with RCA unit-track and Protocol Convertor based on RCA autolink . Price forthe 4-Kbyte kernel is

32K RAM and UART board; disk con- 1802 CPU. programmed with a Forth $100; the extension PROM sells for

tains source and object. Price. $50.

Nucleus. Nicad backed CMOS RAM $100 (qty 10).

1802 figFORTH

retains specific set up parameters. Main Rob Schram program is in EPROM. Full modem Datricon, Inc.

811 disk; load with RCA unit-track and

7911NE33rd Dr. Suite 200

· .

32K RAM and UART board; contains

Portland, OR 97211

Circle 250

16 Digital Design JANUARY 1982



minicomputer environment. imple- Specialized Workshops

mented on an INTEL 86/12 system. FORTH. Inc. will provide specialized

Features include directory-based file workshops at various intervals upon

Freedom Software

structure. full screen editor. generalized sufficient demand from its user base. l/O. multiple vocabularies. dynamic We are also ready to build a program or

Operating system for software package memory allocation. and multitasker. seminar specially for any group or

for loan document preparation and Sophisticated interpreter gives pro- company who wishes to provide a


grammer more control in user interface. FORTH overview on any FORTH re-

Jeff Strickland

Single step debugger. and documenta- lated topic. Workshops currently

ECO Methods, Inc.

tion system with technical or user out- available are: files. target compilation,

1756 Manhattan Beach Blvd.

put modes included. Unit price is $2200. project management. defining words,

Manhattan Beach, CA 90266 Circle 221
68KFORTH A completely integrated disk-based system for MC68000 MPU; monitor. operating system. compiler. interpreter. assembler. virtual memory.

Functions and Floating Point Support
Sophisticated calculation environment through super-colon definitions called FUNCTIONS. Global and Local variables. floating point loops with localled name index. and multidimensional ar-

extensible languages. vocabulary, documentation. scheduling. curriculum design. product specification. Among past users of these services are corporations that wish to evaluate FORTH for projects or for general use.

screen editor. fast dictionary search rays are all supported. FORTRAN E- "The Thread" is formed of users of

· ..

algorithm. double precision arithmetic. and F-like outputs. real-to-integer. and FORTH Inc. related software and seroptional software tools available. integer-to-real conversions included. vices. THREADS exist in New EngFORTH-79 standard vocabulary. Unit Uses Intel 8087 numeric processor for land. New York. Delaware Valley.

price is $795; $595 (100 unit+).

fast. stable calculations. Trans- Washington D.C.. Florida. Chicago.

Lee Sorensen

Empirical Research Group, Inc.

P.O. Box 1176

Milton, WA 98354

Circle 222

PROM based fig-FORTH for TI TM990/101M (9900 based boards).

cendental math and single or double precision . Unit price is $300.
Assembler and MetaForth
For iAPX 86/10 or 86/20 systems. creates target compiler environment to generate new FORTH Kernels or any software system. Non-RPN Assembler (very similar to Intel's ASM-86) sup-

Minneapolis. Houston. Palo Alto. and Los Angeles. with chapters forming in Europe. Canada. and Japan. The user group provides inter-customer communications. a newsletter and a collection of user-developed software and techniques called "The Dictionary."
Introductory Course

ELFORTH consists of six EPROMs porting true labels with forward ref- This intense one week hands-on course

containing fig-FORTH. the fig editor. a erences. Colon definition compiler is taught on the premises of FORTH.

TIBUG type monitor. an assembler and allows high-level routines in target Inc . in Hermosa Beach. California.

a disk interface. The fig-FORTH software. Unit price is $500.

Course outlines and schedules are

MATH pack has been expanded and Fillmore Systems, Inc.

available upon request. Who should

largely re-coded in assembly for speed. 5227 Highland Road

attend? New FORTH programmers and

Additional words and documentation Minnetonka, MN 55343 Circle 224 project managers. language evaluators.

have been added to allow the easy

product designers. Price is $1125 for

implementation of interrupt driven routines . ELFORTH is configured for the development and implementation of real time. interrupt driven. PROM

polyFORTHTM Workshops

one person. $1000 each for two or more.

One-day session offering an in-depth

analysis of polyFORTH and the power Intermediate Techniques


based monitor and control systems with or without concurrent operator access to the full FORTH system. Unit price is

it gives you to write your own unique This course is targeted at FORTH proapplications. By the end of the day grammers who have either completed attendees are able to write simple the preliminary course or have equiva-


FORTH applications. Held in: Los lent FORTH knowledge. Subject mat-


Walt Winter Engineering Logic 1252-13th Ave Sacramento, CA 95822

Circle 223

Angeles. Boston. New York. Minneapolis. Philadelphia. Houston. Tampa. Palo Alto. Chicago. San Diego . Price is $145 .
polyFORTH Seminars

ter includes style and special techniques for many common programming situations. The course is a three day. hands-on experience with a lab. Price is $750 for one person. $650 each for two or more .

Half-day in Los Angeles. Boston. New

York. Minneapolis. Philadelphia. Educational Services

Houston. Tampa. Palo Alto. Chicago. FORTH. Inc . welcomes inquiries from

Utopia FORTH

San Diego - for software managers any FORTH user or implementor who and engineers to demonstrate how needs course development and/or

Utopia FORTH is a new generation polyFORTH improves programmer product training either for themselves

FORTH designed for a sophisticated productivity . Admission is free.

or for their own customer base.

JANUARY 1982 Digital Design 17


Project Management Course

Stepping FORTH self-teaching disk- $5.450: and pF8080/I0-4 for SBC-204

Targeted at individuals who wish to ette. 60-day warranty. and 60-day free Disk Controller. $5.450. Intel 8080

write. manage or schedule FORTH - Hotline Support.

options include: D00/8080 File Man-

or manage FORTH programmers projects. this 3 day course provides DEC PDP- &LSl-11 polyFORTH

agement. $950; A05-I4/80 I4-bit Fixed-point Fraction Arithmetic. $250;

knowledge of coding styles. develop- PDP- I I and LSI-I I products are the A07/80 Normalized I6-bit Ratio of32-


ing tools. documentation methods. same. All DEC systems require 32 kB bit. $I 25; A 10/80 Integer Square Root

personnel management and implemen- memory and a DL- I I or DLV- I I con- (30-I5 bits). $75; A20-I4/80 I4-bit

tation. Price is $600 for one person. sole. pFI I/RXOI. for RXOI Diskette is Trig Functions (incl. A05- I4/80).

$450 each for two or more.

$5. IOO; pFI I/RX02. for RX02 Disk- $250: V8080/UPP UPP IOI PROM

ette is $5.100; pFI I/RLOI. for RLOI Programmer. $300; V8080/ICE ICE-


Disk is $7 .300. including file manage- 80 Driver. $500; and V8080/534 iSBC

In this one week hands-on course the ment plus Media; pFI I/RK05. for 534 4-port Serial MUX Driver. $500.

student gains a working knowledge of RK05 Disk is $7.300 and includes File

FORTH. Inc. 's approach to Data Base. Management plus Media. Options CP/M polyFORTH

user interfacing. file organization and include DOO/ 11 file management. The overall performance of CP/M management techniques. Price is $ l.500; A05-14/ I I I4-bit Fixed-point based systems may be somewhat f

$I 200 for one person; $ IOOO each for Fraction Arithmetic. $250; A05-15/I I degraded in comparison with stand-

two or more.

I5-bit Fixed-point Fraction Arithmetic. alone polyFORTH implementations

Advanced Course

$250; A06/LSI- I I Floating Point due to CP/M conventions. pF8080/ Package for LSI- I I EIS. $500: A07/I I CPM for 8080 or Z-80 based CP/M

FORTH. Inc. 's hands-on advanced Normalized I6-bit Ratio of32-bit ratio. systems is $5. IOO (8" single-density

FORTH class provides the FORTH $I 25; A I0/ 11 Integer Square Root (30- floppy); pF8086/CPM for 8086 or 8088

programmer with a thorough knowl- I5 bits). $75: A20-14/l I 14-bit Trig based CP/M 1s $5. IOO (8" single-

edge of polyFORTH multitasking and Functions (incl. A05-14/l I). $300; density floppy) .

target compilation . These techniques A30-I5/ I I Log. Exponential Funccan insure the success of a FORTH tions (15-bit fixed-point). $300; VI I/ IBM Series/1 polyFORTH

language-based product and can pro- DZ DZI I MUX Driver. $500; VI I/TU pFSI for IBM Series/I includes File

vide a significant decrease in the devel- TU58 Cassette Driver & Utility. $500; Management; driver for 3 IOI Termi-

opment cycle. The student actually VI I/MT TUIO Tape Driver & Utility. nal ; driver for 4962. 4963. or 4964

develops a real-time process control $300; GO I-TEK/l I Tektronix 40 IO disk; driver for 4978 display; driver for

application during the course. The IO% type Compatible Graphics. $750 .

4952 real-time clock; and driver for


discount applies to software services subscribers . Price for one person is Intel 8086 polyFORTH

4973 or 4974 printer. Price is $8 .250. VS I/MM 4955 Memory Management

$ I500; two or more persons. each$I250. For SBC-86/12 board; incl. four 27I6 Package is available for $2.000.

PROMs . pF8086/12-I is for SBC-20I

Applications Programming

Disk Controller; pF8086/ I2-2 is for Motorola polyFORTH

Working in conjunction with your SBC-202 Disk Controller; and pF8086/ pF6800/EX-B EXORcisor II for 6800


programming staff. FORTH. Inc. can I2-4 is for SBC-204 Disk Controller. Processor is $5. IOO; pF6809/EX-B

supply special Application Program- All are $5.450. Options include DOOi EXORcisor II for 6809 Processor is

ming. Our technical staff is exper- 8086 File Management. $1.500; AIOI $5. 100: pF6809/30 EXORset 30 (6809

ienced in process control. data acquisi- 8086 Integer Square Root (30-15 bits). Processor) is $5. IOO. Options include:

tion. mathematical analysis. image $75; V8086/534 iSBC 534 4-port Seri- D00/6800 File Management for $950;

processing. interactive graphics. and al MUX Driver. $500; V8086/UPP D00/6809 File Management for $950;

data base management.

UPP IOI PROM Programmer (incl. A05/I4-09 I4-bit Fixed-point Fraction


Custom Processor polyFORTH

special cable). $500; V8086/CEN Par- Arithmetic for $250; A I0/09 Integer allel Centronics Printer Driver. $I 50. Square Root (l3-I5 bits) for$75; A20-

While they may not list your CPU as one of their standard products. Intel 8080 polyFORTH

I4/09 14-bit Trig Functions (incl. A05- ·
l4/09) for $250; A30-I4/09 Log. Ex-

FORTH. Inc . supports an array of sys- pF8080/230B is for Intel MDS Series II ponential Functions (I 5-bit fixed-point).
. tems and will supply on site installation Model 230. 235. and costs $5. IOO; $300; V6800/CEN Parallel Centronics

in many cases.

pF8080/l B is for Intel MDS-800. 20I Printer Driver. $I50: and GOI/30


Disk Controller. and costs $5.100 EXORset 30 Graphics for $950 . (single density); pF8080/2B is for Intel

All polyFORTH systems are supplied MDS-800. 202 Disk Controller. and pF68000

with: polyFORTH Disk. PROMs costs $5. IOO (double-density); Pol yFORTH for Motorola 68000 CPU.

(where noted). installation instructions (as needed). complete system source

pF8080/2 comes with SBC-416 PROM Board. $5.550. The following systems

RCA 1802 polyFORTH

listings and glossaries. Using FORTH for SBC-80/10 boards. include four pFI802-UT21 COSMAC CDS-007 Manual (168 pp.) . polyFORTH Ref- 27 I6 PROMs: pF8080/ IO- I for SBC- and UT2I PROM Utility. $5.100:


erence Manual (320 pp .) . CPU Sup- 20 I Disk Controller. $5.450; pF8080/ pF1802-IK with IkB of 2708 PROM.

plement to the Reference Manual, I0-2 for SBC-202 Disk Controller. . $5.I75; pF1802-2K with 2kB of2708

18 Digital Design JANUARY 1982

Automated Testing for Electronics Manufacturing


We invite technical papers on these subjects for presentation in General Sessions and Workshops

Field Testing


Bare-Board Testing Loaded Board Functional

and In-Circuit Testing

LSI Board Test

LSI Component Test

Digital Diagnostics

Microprocessor Bus

Fault Isolation

Abstract Deadline : April 15, 1982

Analog Board Test Analog Diagnostics Bubble Memory Testing Burn-In/Temperature Cycling Logic Analysis Techniques Waveform Analysis Electro-Optic Testing Test Requirements Analysis Interfacing Devices Simulation Automatic Test Generation Systems Suppa~ Management ATE Management ATE Acquisition Testability Economics of Loaded
Board Testing ATE System Calibration Using IEEE Bus Instruments Signature Analysis

r-------------Abstract Submission Form-------------,

Please attach this form with your abstract or paper idea.

001 /82 1



Title _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __


Qompany _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __


Address _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _~



City _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ State _ _ _ _ _ Zip - - - - - - - - - - - - -


Phone No. (

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ext.




Please complete one: Abstract attached

Abstract to come by

Send abstracts (200-500 words) and short biograpies by April 15, 1982 to Mary Habosian, ATE


Seminar/Exhibit, Morgan-Grampian Expositions Group, 1050 Commonwealth Ave., Boston, MA 02215. Or I

L-ca-ll:-(61-7)-23-2-5-47-0. ------------------------------~

Sponsored by Electronics Test and cosponsored by Circuits Manufacturing, Digital Design and Design Engineering magazines.


PROM. $5.225. Options include: VI I- telephone "hotline" support: docu- - virtual memory. With manual and tu-

PL/1802 Prolog PROM Programmer. mentatiun updates on the polyFORTH torial. Unit price is$24.95.

$200: A05-14/1802 14-bit Fixed-point Reference Manual and your CPUFraction Arithmetic. $250; A05-15/ · specific User's Supplement; system 1802 15-bit Fixed-point Fraction updates (diskette and source listings); Arithmetic. $250; Al0/1802 Integer and two allowances ofa 10% discount

Greene Software 6169 Fawn Meadow Victor, NY 14564

Circle 227

Square Root (30-15 bits). $75; A20-15/ on FORTH. Inc. courses.

1802 15-bit Trig Functions (incl. A0515/1802). $300: and GOl-TEK/1802 Tektronix Compatible Graphics. $750.

Starting FORTH A 380 page tutorial by Leo Brodie on the FORTH language that offers clear


RCA Microboard Development Systems OS 1802-2 includes CDP 18S601 board plus 16kB memory board. iCOM disk. parallel printer controller. UART board. power supply. chassis. case. with polyFORTH for $12.500; OS1802-2U upgrades DSl802-l (picoFORTH) to DS1802-2. $11.950.
pFZ8000 PolyFORTH for Zilog Z-8000 CPU .

explanations and examples for beginners as well as experienced users of FORTH.
This user's manual covers all basic aspects of polyFORTH. with problems at the end of each chapter. Learn about postfix notation. the dictionary. logical operations. data structures . the text editor. string handling. and more. 168 pp; $25 .

Automatic Data Link (AOL) processor program processes AOL information on military data links to include Missile Battery Data Link (MBDL) and the classified Army Tactical Data Link One (ATDL-1) and Tactical Data LinkB (TADIL-B). AOL is processed and formatted for subsequent link and systems analysis .
Mr. R. Day Intercon Systems Corp P.O. Box 6024


Programmer Cards

El Paso, TX 79906

Circle 228

PicoFORTH Systems

Includes over 300 polyFORTH com-

PicoFORTH systems are supplied with: mands for handy reference. FORTH-79

picoFORTH diskette; PROMs where Standard. Free.

noted; installation instructions as needed: Using picoFORTH; CPU User's Manual: Stepping FORTH Tutorial: and a 60-day warranty .

FORTH, Inc. 2309 Pacific Coast Highway Hermosa Beach, CA 90254 Circle 225

FOR/MAT This screen editor has over 20 different

cF8080/230B. Intel MOS Series II

commands for cursor positioning. text

Model 230 is $195; cF8080/1B. Intel

modification. tabs. relocating lines.

MDS-800. 201 Disk Controller (single-

spreading lines. and moving lines to

density) is $195 : cF8080/2B. Intel

other screens. Unit price is $50.

MDS-800. 202 Disk Controller (doub le-density) is $195 ; cF8080/ CPM. 8080 or Z80 based CP/M system (8" sing le-density diskette) is $195; cF6800/EX. Motorola 6800 EXORcisor II is $195: cF6809/30. Motorola

Development/Prototyping System
FORTH System when RS 232 terminal connected. with 12K FORTH ROM. 32K user RAM. 30 screens for source in RAM to FIG standard. When appli-

Ron Huffman KV33 Corp P.O. Box 27246 Tucson, AZ 85726

Circle 229

EXORset 30 is $195 ; cF1802/UT21. cation code complete. can be used as

RCA COSMAC CDS-007 is $195; prototype. Sealed case. built-in 9 day

cF1802/601. set of picoFORTH battery. 8 bit I/0 port. tone keyboard. 8

PROMs for CDP18S601 Board is $495 ; DS 1802-1. RCA CDPl8S601

digit display. 20 digit bar display . Designed for real time industrial appli-

Z-80 Development System


Board with picoFORTH in PROM is cations in logging control. Many extra Complete program development sys-

$995: cFl l/RXOI. DEC PDP- & LSI- FORTH functions (320 in total). Unit tem for Z-80 microcomputers including

11 (RXO I Diskette) is $195; cFI I/ price is $2900: $2610 (20 units).

interpreter/compiler with virtual mem-

RX02. DEC PDP- & LSI- I I (RX02 David Esterson

ory management, Z-80 and 8080 as-

Diskette) is $195.

Golden River Corp

semblers, line editor, screen editor,

7315 Reddtield Ct.

decompiler. utilities. and demonstra-

Support Services

Falls Church, VA 22043 Circle 226 tion programs . 70 page user manual.

All systems listed are fully supported

. Requires 32 kB RAM. CP/M 2.2 or

by FORTH. Inc. A contract for polyFORTH Support Services is available on a one-year basis at these rates: when ordered with polyFORTH system . $750; when ordered separately. $950. PolyFORTH support services include

Fig-FORTH for SWTPC 6800 computer and Percom disk . Contains all of the high level commands published by the 1978 FORTH standards project. along with variable length names and

MP/M I. I operating systems. Optional floating point arithmetic and crosscompiler packages also available at extra cost. Unit price is $50.
Ray Duncan Laboratory Microsystems 4147 Beethoven St.


Los Angeles, CA 90066 Circle 230

22 Digital Design JANUARY 1982


Operating System/Programming Language
This is the polyFORTH OS/language designed by FORTH Inc. but adapted and distributed by Lynx . It includes an assembler. compiler. 2 levels of interpreter. virtual memory multitasking and debugger. Lynx supports CPUs not supported by FORTH Inc: TI 9900. DG NOVA and CAI-LSI-4 series. Unit price is $4750 .
Lynx 3301 Ocean Park Blvd, Suite 207 Santa Monica, CA 90405 Circle 231

FORTH Compiler

ProFORTH for the Tektronix 8002. a

powerful superset ofFORTH-79 forthe

professional. Compiles ROMable code

in place. even in a discontinuous memory configuration. Code. dictionary. and RAM areas can be separated as initially compiled . Multiple dictionaries with selective purging enable

development of large applications on

line . Unit price is $2250 .

Robert H. Hertel

Microsystems, Inc.

2500 E. Foothill Blvd., Suite 102

Pasadena, CA 91107

Circle 234

control: greatly simplifies control of

interrupts: includes a full mutitasking

executive; and. its file system is com-

patible with popular /.LPs. Implementa-

tions include PDP- I I family. Zilog

Z80 and Z8000. Motorola 6809 and TI

9900. Single user Class A support starts

at $750.

Nortek Inc.

2432 NW Johnson St.

Portland, OR 97210

Circle 249


fig-FORTH for NOVA

The fig-FORTH model implemented

Custom Medical Software
Clinical (not bookkeeping. billing. or accounting) record keeping.
William J. Schenker, M.D. Medical Information Systems 2086 Essenay Avenue Walnut Creek. CA 94596 Circle 232
MicroMotion FORTH-79
The only commercially available Apple II implementation of the new (Oct. I980) international FORTH standard. Tutorial manual included . MicroMotion FORTH-79 includes a full screen editor. 6502 macro assembler and CORES graphics routines. Unit price is $89 .95 (qty discounts available).
Micro Motion 12077 Wilshire Blvd, Suite 5060 Los Angeles. CA 90025 Circle 233
Engineering Services Hardware and software engineering ser~ vices for 1-LP-based products. Complete facilities. including a universal development system with in-circuit emulation. Extensive FORTH library optimized for real-time applications: multitasking. I/O. floating point math. etc .

Nautilus System fig-FORTH Cross-Compiler

Cross-compiles the fig model or extension for ROMable. headerless code . Forward reference capability. Includes source of cross-compiler. 107-page document in 3-ring binder. Sold with

single CPU license. no royalties claimed on anything cross-compiled. Machine readable versions CP/M. TRS-80. Z89 & Northstar. Unit price is $200; $I 50 after first order.

Jerry Boutelle Nautilus Systems P.O. Box 1098 Santa Cruz, CA 95061

Circle 235

SPICE for DEC Falcon
For DECs KXTI I (Falcon) SBC. SPICE combines an operating system. high-level programming language. assembler. file system . and multitasking executive. It is designed specifically for system integration and controller applications and offers direct access to the machine's resources. making it ideally suited to hardware familiarization and debugging. By ~upporting mixed high-level and

for NOVA line co puters. Supplied on a hard sectored diskette. An assembly listing file which can be assembled by Macro-Assembler and an assembled save file which can run standalone. Supplied with the source listing. Unit price is $50 .

Systems Guide To fig-FORTH

This book explains how' s and why's of the fig-FORTH system. based on source codes of the fig-FORTH Model. I4 chapters on: language definition of FORTH; fig-FO RTH : an operating system: text interpreter; address interpreter; compiler; error handling; terminal input and output; numeric conversions; dictionary; virtual memory; defining words and the code field; control structures and immediate words; editor; and assembler. Unit price is $25 plus postage; qty discounts available .

Dr. C.H. Ting Offete Enterprises, Inc 1306 S "B" St., San Mateo, CA 94402

Circle 236

FORTH Real-Time OS

assembler code. critical routines can

execute at full processor speed. While FORTH Language and Utilities for


Efficient. stand-alone multitasking and I/0 control system for time-critical. interrupt intensive applications. Supports code and high level tasks as well as multibuffered. interrupt-driven I/O for character and block devices. Drivers are table controlled and all run time code is in assembly language. Unit price is $I750.

inspired by FORTH. SPICE offers the following advantages : is inherently ROMable; implements a consistant syntax: is user oriented in its messages; is modular and easily expanded; supports a full set of control structures; uses standard assembler notations; includes a set of primitives for process

the PDP-11
FORTH for the LSI- I I and other POPI I systems using the RT- I I operating system. Features include: a video screen editor. PDP- I I assembler. 8080 cross assembler. RT-I I system calls. interface to external program modules. floating point math. string operations.

and extended program control struc-

tures. debugging tools. and other util-

JANUARY 1982 Digital Design 23


ities. Unit price is $495.

Custom Machine Control SW

Peter Bates

Z-80 or 650X FORTH software for

Pacific Digital Associates

control of high-speed industrial ma-

3308 E. Laurel Ln. Phoenix, AZ 85028

chines and equipment. Light machinCircle 237 ery control software includes the con- QSFORTH

trol of: four and five phase stepper Fig-FORTH implemented on the Atari

FORTH Dialect for OASIS or

motors. solenoids. industrial actuators. 800 Personal Computer: a disk based


opto-electronic sensors. keyboards. system. Five modules are included: the

FIFTH is a FORTH style programming displays etc.

FORTH kernel , an EXTENSION that

system with several major extensions including overlays and a·n extension of the FORTH compiler concept to give the user additional control of the system. FIFTH programs are ROMable. This

William Reed Polyarts Associated, Inc. P.O. Box 23122 Seattle, WA 98111

Circle 240

includes some additional useful words.
an on-screen EDITOR. and an I/O
module that makes 1/0 easy to set up.
Unit price is $79.95.

feature. along with several cross-com- Standard fig-FORTH for the

FORTH for the Sorcerer

pilers (8080. Z80. 8048). makes Alpha Micro

Fig-FORTH implemented on the Exidy

FIFTH an ideal µP development system. Pacific Polytechnical Corp P.O. Box2780 Santa Cruz, CA 95063 Circle 238
fig-FORTH for Atari 800/400 pns-FORTH Version l .3 (Minimum System) features : full screen (40 x 24) direct cursor control editor: standard fig tool words: relocatable disk buffers: keyboard filter (to reduce operator

This fig-FORTH (FORTH Interest Group) product is aligned with the 1978 standard of the FORTH International Standards Team and allows complete access to Alpha Microsystems ' multitasking operating systems. AMOS. µA/FORTH implements full-length names up to 31 characters. extensively checks code at compile-time with error reporting. contains string-handling routines and a string-search editor. and permits sealed vocabularies to control

Sorcerer. Cassette storage plus simu-

lated disk memory in RAM. Custom

features added to fig-FORTH include

an on-screen EDITOR. a serial RS-232

driver. cassette interface words. and
option for 8-bit 1/0 to allow video

graphics with the Sorcerer. Unit price is

$59.95 .

Sandra Pierce

Quality Software

6660 Reseda Blvd., Suite 105

Reseda, CA 91335

Circle 242

error): UN: compiler. System required user access. Included is a FORTH

is l6Kbytes RAM & at least l disk assembler. permitting structured. inter-

drive. Documentation supplied con- active development of device handlers.

sists of: glossary of fig and extension speed-critical routines. and linkage to

words: source screens; equates: English operating systems or to packages written description of commands. Unit price is in other languages. The distribution 6502 FORTH 2.0

$50: qty discounts available.

disk is in single density format. and A floating point math vocabulary with

includes all source code. The diskette transcendental functions. a string han-

pns-FORTH 1.3 With 1/0

includes an editor. a FORTH assembler. dling vocabulary similar to BASIC.


and string package in FORTH source and a 6502 assembler with Macro de-

Features: pns-FORTH Minimum Sys- code. Unit price is $130.

fining capability are among the more


tem plus: extension to provide hooks to Atari central I/O system for all resident


notable features of 6502 FORTH 2.0. The language is available in versions

device handlers: a complete player- This computer aided instruction course which run on the KIM-I. AIM 65. and missi le (object oriented) graphic by Creative Solutions. Inc . is intended SYM- l microcomputers (custom and


system is provided. in addition to bit- to interactively guide the beginning EPROM version can be configured).

map graphics. Other modules include FORTH user through initial terminal Package includes a complete source light pen interfacing and animated sessions. Over 100 frames of step-by- listing. a user manual and the object


character displays . Extra documentation includes source & glossary. Unit price is $70: qty discounts available.

step instructions and clear examples are provided on the primary concepts of FORTH. Structured programming techniques are incorporated throughout

code on cassette. $90 .
Brenda Rehnke Eric C. Rehnke, Technical Services


pns-FORTH 1.4 Cross-compilable source screens for

the program development stages and a typical FORTH Text Editor is intro-

1067 Jadestone Lane Corona, CA 91720

Circle 243

any 6502 µP system. Produces header- duced. On diskette: license agreement

less. ROMable code for any address required . Unit price is $45. $l0 when


space. Unit price is $150.

purchased with µA/FORTH.

Robert Gonsalves

Howard J. Dernehl

Pink Noise Studios 1411 Center St. Oakland, CA 94607

Professional Management Services 724 Arastradero Rd. #109


Circle 239 Palo Alto, CA 94306

Circle 241 AM-FORTH is an implementation of

24 Digital Design JANUARY 1982


the FORTH programming language software . Examples of previous prod- ware development system; products go

and system on the Alpha Micro com- ucts: Telephone call restrictors. spe- into 8K or more of ROM. with l K

puter. Operating under the Alpha cialized keyboard data entry/retrieval scratchpad RAM . It incorporates a

Micro Operating System (AMOS). it systems. thermal printers. RS232 data command processor. compiler. editor

provides all the usual features of routing systems. printing press moni- and assembler. all memory resident .

FORTH: interpreter. compiler. as- tors. 1000 channel multiplexors. & Programming creates new commands

sembler. and disk file structure. Utility traffic controllers . Also complete docu- which become available as sub-

functions are also provided for a video mentation & manufacturing facilities . routines for subsequent commands.

and line editor. string operations. data structures. and floating point math. AM-FORTH is closely integrated in the AMOS environment: the program is reentrant. allowing one copy to be loaded into AMOS system memory and shared

Robert F. Downs Technology Management Inc/ Development Associates 1520 S. Lyon Santa Ana, CA 92705 Circle 246

Product is based upon figFORTH and further includes: visual (screen) editor. machine coded array handling. very fast disk I/O. configurable to memory size. creates tum-key applications. and CP/M file conversion & system calls.

by all users on the multi-user Alpha Micro system; AM-FORTH memory

OSI-FORTH 2.0/fig-FORTH 1.1

Unit price is $350 (if other than 8" disk. add $15.)

expands and contracts as needed to accommodate the FORTH dictionary;

This is a full implementation of the FORTH Interest Group Version 1.1 of

CP/M Utility Package

1/0 is provided to AMOS random and FORTH. It runs under OS-65D3.2 (or Converts CP/M files into FORTH

sequential files; access to AMOS 3.0. 3.1). on any disk-based Ohio screens and vice versa. either text

TIME. DATE. and special CRT func- Scientific system. and has access to all format or binary image format. Loads

tions is included. Complete imple- DOS commands and resources. In- (interprets) FORTH source from CP/M


mentation documentation is provided cludes resident text editor. assembler. file enabling CP/M editor to create in the "Installation and User's and utility screens for transferring the FORTH programs . Allows two way


Manual". AM-FORTH is delivered on system to a new disk. initializing interchange between RAM and CP/M

an AMS or STD format disk including library and system disk block storage file; FORTH CP/M system calls. and

source code. Unit price is $150.

tracks. copying screens from disk to creation of file control blocks. Code is


Sierra Computer Co. 617MarkNE Albuquerque, NM 87123 Circle 244

disk. and reconfiguring the system memory usage . Price is $79.95 .
Daniel B. Caton Technical Products Co.

well-documented. enabling user modification. Unit price is $50.
FORTH User Manual & Tutorial

P.O. Box 12983

The FORTH user manual and tutorial is


Gainesville, FL 32604

Circle 247 designed to be used at the terminal while FORTH is running. It leads the

tFORTH+ and firmFORTH
tFORTH + is an extension of standard fig-FORTH for 6800 and 6809 µ,P systems. Supplied on FLEX operating system diskettes (other arrangements

Language and Software Development System
An interactive software development system which incorporates a command processor. compiler. editor and assembler. all memory resident. Pro-

user through commands and computer responses . Price credits towards disk purchase. Unit price is $20 (free with Timin FORTH purchase).
Diskette of FORTH Application Modules

possible). firmFORTH is a target com- gramming creates new commands Variety package of FORTH software;

piler for making ROMable code of which become available as sub-rou- contains development tools. math rou-

minimal size; requires tFORTH+ . tines for subsequent commands. Pro- tines. 1/0 routines. recursive examples.

Screen editor and assembler and large duct is based on figFORTH and further etc . Something for every FORTH user.


collection of useful FORTH utilities includes interleaved disk format that Unit price is $75 .

supplied. Unit price. tFORTH+ $250: firmFORTH - $350. Qty dis-

minimizes the time required fqr disk access. providing very fast disk I/O.

Floating Point FORTH Vocabulary

counts available.

Unit price is $95 (if other than 8" disk. Works with decimal numbers . Retains


Raymond Talbot Talbot Microsystems

5030 Kensington Way

add $15). FORTH Development System

the 16-bit & 32-bit integer capability of figFORTH while adding a floating point mode. These are single precision

Riverside, CA 92507

Circle 245 Same as above. but further includes: floating point numbers with seven

visual (screen) editor. machine coded significant digits. All basic arithmetic

array handling. very fast disk I/O. con- functions. integer conversion and

Custom Product Development/ figurable to memory size. creates tum comparison are supported. Run time


key applications. and CP/M file con- error messages warn of exceptional

Development of FORTH Applications version & system calls . Unit price is conditions . Unit price is $100.


& hardware for real-time control. In- $235 (if other than 8" std . disk. add John H. Holmes

house support for LSl-11 & Apple. $15) .

Timin Engineering Co

Expertise in single chip processors such as MCS-48 & 3870. Also experienced ROMable FORTH

9575 Genesee Ave., Suite E2 San Diego, CA 92121 Circle 248

in 8080. 8085. & 6100 hardware & A complete interactive FORTH soft-


JANUARY 1982 Digital Design 25

----SYSTEMS---Designers' Guide To Noise Suppression
ignore noise suppression and grounding rules at your peril

F. ai/ure to follow proper noise suppression and grounding rules is leading to increasing problems for computer system designers. It is a growing problem due to systems that are

more EM I-susceptible, unsophisticated users, increased number of computer systems.



by J. F. Kalbach

controlled. The problems and solutions can be complex . Even if the manufacturer·s grounding rules are followed.

Inadequate noise suppression can damage your Finn - perhaps even put it out of business. One large firm that used a second-sourced µ.C chip that required extra care in noise suppression found its reputation tarnished after it had to wait for the installed subsystems to fail. The alternative was unthinkable: a massive recall. Other Finns have run into worse problems.
Man-made noise currents and voltages arise from static as well as operation of power lines. electrical loads. telephones. radio. TY and radar. Since electrical resistance between two ground points is never zero. a broad frequency spectrum of electrical noise exists between any two earthed conductors. Although voltage can be reduced by connecting a conductor between them. the noise current which flows can induce a related voltage and/or current in nearby ungrounded circuits. If the interconnecting conductor is the grounded conductorof a signal pair or the outer conductor of a coaxial conductor. the noise will be mixed with the signal and possibly corrupt the transmitted intelligence.
This article will discuss measures that you should take to prevent your next system from falling victim to inadequate grounding and noise suppression.
installation of electronic equipment
In the interest of achieving high-signal processing rates . compact hardware and low energy requirements . electronic circuits and circuit elements are continuing a trend to very low energy signals at very high bit rates. typically greater than 10 Mbps. Frequency content of the output of signal drivers and ability of receivers to respond may be in the 30 to 100 MHz range or greater- in a frequency spectrum where wavelengths are shorter than many interconnecting cables. The behavior of conductors at such frequencies must be predicted on the basis of radio technology rather than power or voice frequency telephone circuits.
Manufacturers of computer and digital controller products will usually specify grounding techniques and arrangements to be used in their installations. Most of these are based upon legitimate engineering and physics principles. However. more often than not. these are followed by rote rather than through any basic understanding of the phenomena being

electrical noise can still be a problem which only a grounding

specialist can identify and resolve. All the answers cannot be

foreseen . However, a few basic explanations should help

those involved with the installation and use of computer-type

circuits and their grounding systems.

The overall noise problem is as follows:

· Overly sensitive electronic circuits may be in a highly

disturbed environment.

· Disturbances may be externally or self induced .

· Interfering signals and circuit susceptibility may cover an

extremely broad frequency spectrum (d-c to gigahertz).


· Symptoms may be intermittent. Interaction between

randomly occurring noise impulses and the specific moments

when signal circuits are enabled and are at their most sus-

ceptible phase has a low statistical probability of occurrence. Noise pulses capable of creating malfunctions will not


always do so.


· Electrical noise. marginally defective components and

software bugs can all create similar malfunctions. making it

difficult to distinguish between various possible causes of

signal or data corruption.

The three basic approaches to solving these noise prob-

lems are:

· Eliminating or reducing the noise at its source.

· Reducing the disturbed circuit's susceptibility.

· Reducing the intercoupling between noise source and

disturbed circuit.


grounding functions

Grounding is a very important part of each of the above

solutions. Although grounding accomplishes multiple func-

tions. many an individual is concerned with only one and may violate the other requirements out of ignorance or


because it is not his concern.

Safety considerations must take precedence whenever there is a conflict of interest. However. the task to be


accomplished is to make the product installation safe and at

J.F Kalbach is a consultant and is a recognized authority on noise suppression techniques. He can be reached at, 920 Alta Pine Drive, Altadena, CA 91001.

26 Digital Design JANUARY 1982

,~ Today's measure of a print- impressions and greatly every time you design a riber's performance goes increase the life of every bon cartridge featuring

beyond line speed and ribbon.

Porelon ink rolls.

purchase price. The true test Better impressions, in- Find out how simple it is to

is print quality and cost- creased ribbon life. At less add this performance fea-

· per-character operating cost. That's what you'll get ture to your impact print-

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designed specifically for

call 615/432-4134, or write:

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Porelon, Inc., 1480 Gould

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prove the number of quality


© 1981 by Porelon. Inc.A subsidiary of Johnson Wax.


Circle 10 on Reader Inquiry Card Porelon is a trademark.

Type TN Earthing

Type TT Earthing

Type TN Earthing


Type IT Earthing


Figure 1: European classifications of systems for grounding show the TN, TT and IT earthing types. (From ECMA/TC12/775/52).

the same time satisfy all practical noise emission and susceptibility requirements .
The basic purposes of grounding are: Safety: touch voltage limitation. Equipment ground conductors which connect the frames of products to ground and to each other are intended to limit touch voltages to safe values in the event of insulation or component failure within the product or in the conductors which supply power. Except during a fault to ground and until protective circuit elements interrupt power from the source, the voltage difference between both ends of an equipment ground conductor should ordinarily never exceed a fraction of a volt at power frequencies. The conduit and the grounding conductor are not intended to carry any portion of load current . They are to carry only fault currents, leakage currents and noise currents.
At power frequencies , 30V RMS is commonly specified as an upper limit for "safe" voltages. A momentary excursion above this during the time it takes for a fuse or circuit breaker to clear a fault is not considered a significant hazard .
At higher frequencies and impulses, the human body can tolerate much higher voltages and currents than at power frequencies. This is fortunate because as frequency content increases, the inductive impedance of grounding conductors and the voltage drop for a given leakage or noise current will also increase. Noise impulse voltage signals of 150 to 200V appear regularly on ground conductors associated with 120V circuits. However, their duration is usually measured in µsecs and they cannot normally be detected by touch . · Safety: ground fault return path. Any fault or leakage between an ungrounded conductor and a grounded enclosure will produce fault current. The leakage current may be hannlessly drained away, but a short circuit current must be promptly terminated by protective fuses or circuit breakers . If the same devices which protect against line-to-line or line-to-neutral faults are to protect against line-to-ground

Complying with FCC

The FCC recently promulgated acceptable limits of EMl-

induced field strength at specific frequencies and dis-

tances from a radiating electronic device. These limits

are shown below for compliance of Class A products

and certification of Class B products; and the FCC prom-

ises strict enforcement. The FCC's acceptable limits of

field strength are as follows. Class A devices - At a distance of e meters



acceptable field strength

30-88 MHz 88- 216 MHz 216-1000MHz

300 µV/m 500µV/m 700µV/m

Class B devices -At a distance of 3 meters


acceptable field strength

30-88 MHz



88 - 216 MHz

150 µV/m

. 216 - 1000 MHz

200 µVim

Verification of Class A devices requires testing to


insure prescribed limits of EMI radiation. The FCC

requires the manufacturer to retain test data on file for

the agency's review. Certification of Class B devices

requires that test data, and upon request the product

itself, be submitted to the FCC for approval. Certification


follows approval

Class A devices are those intended for use in

"commercial , industrial or business environments."


Specific examples include computers and peripherals,

digital cash registers and electronic typewriters. Less

likely to cause interference because of the "friendly"

industrial environment, Class A devices must comply

with generally lenient standards.

28 Digital Design JANUARY 1982

faults, the ground return path must not have a high enough impedance to limit the fault current. Otherwise , it would not promptly trip the protective device.
This requirement dictates that the electrically continuous conduit and equipment ground conductor be connected directly to the neutral of the power source at or very near its origin. This is at a secondary of a transformer, output of a motor-generator, or at the building entrance service equipment if no isolating transformer is interposed.
In the above connection between conduit or enclosure and neutral, fault current does not flow through a separate connection between the enclosure and a driven earth or other qualified ground connection - at least not from faults to enclosures . If an arrangement of grounding were to be used where fault currents had to pass through two driven earth stakes or rods , the resistance of these grounds would prevent many circuit breakers from tripping . A very low ground resistance for a driven ground might be 5 ohms (25 ohms is often acceptable) . Two in series would be 10 ohms. In a 120 V circuit the 10 ohms of resistance in series with a ground fault would allow 12 A to flow. This is not enough current to trip the lowest circuit breaker rating in common use , namely a 15 A breaker.
To insure prompt operation , a circuit breaker must see 10 times its rated current protection or more . Ground path resistance between the fault point and connection to neutral plus all other circuit resistance cannot exceed 0 .8 ohms for a 15 A circuit. For a 150 A circuit, this would be 0 .08 ohms max. It is clear that driven grounding rods cannot meet this requirement , but direct connections can.

It should be pointed out that the grounded neutral protection system is not universally used throughout the world . In Europe, especially France, there is a system called an " IT' ' system where the power source neutral is allowed to float or is connected to ground through a high impedance . A line to ground fault creates no problem until there is another fault on another line or on the neutral to ground. A high neutral to ground voltage indicates the presence of a ground fault and can be made to actuate a shunt trip . Alternatively , current summing ground fault detectors can identify which branch circuit is at fault and selectively trip the proper circuit breaker.
Still another scheme is the " TT" system where power source and load are each independently grounded through their own respective driven earth grounds. As previously explained, a ground fault would not necessarily create sufficient fault current to ensure operation of the protective fu se or overload circuit breaker. A summing type ground fault detector would sense the fault, however.
The predominant type of grounding in Europe and United Kingdom is the "TN" system. Like that used predominantly in the US and Canada, this signifies a grounded power source with the frame of the load grounded directly through a separate safety ground conductor to the neutral at the power source. Zero potential reference and voltage equalization. Connecting the frames of all parts of a system to a common point which is grounded is intended to bring them all to the same potential. This is supposed to eliminate voltage differences between various grounded parts in the system .

E;MI Requirements

Class B devices, intended for use in a "residential

environment", include personal computers, electronic

games and calculators. The relatively "hostile" home

environment with its greater opportunity for interference

requires certification by the FCC to more stringent


Chomerics Radiation Test Services operates two
facilities in its laboratory: a 1700 tt2 indoor anechoic,

three-meter test site ; and an open field, 10-meter test

site. Both are equipped with tunable dipole, biconical


and log periodic antennas providing reception capability from 20 to 1000 MHz. Some of the measuring instru-

ments available to the two sites include receivers for


radiated measurements at frequencies of 30 to 1000

MHz, panoramic display systems, automated signal

charting devices, spectrum display analyzers and cali-

bration equipment.


Solving excessive EMI radiation problems is the end goal for which testing is but one key element. A broad

problem-solving capability, such as at Chomerics, is

needed , as the following example shows. This example

deals with unacceptably high EMI emissions from


remote typesetting terminals connected in two places by

coaxial cables to a central electronic processing unit.

The system handles information and generates, as a

video output, high-speed graphics. The terminal comes

equipped with a high-speed, µP-based keyboard.

Initial radiation tests showed significant emanations

from 50 to 250 MHz. Signals near to or exceeding the

limits occurred at six places. Counting the repetition

frequency of the resident line pattern indicated that

these signals were closely related to the video content of

the graphics screen. Without the graphics cable

attached to the terminal, little radiation was measured ; with the cable attached, large amounts of radiation were detected whether or not the terminal power was on.
Modifying the terminal so that the shielding provided by the graphics coaxial cable would be maintained when it was connected to the terminal was indicated. The original design failed to recognize the importance of making frequent contact between the various metal chassis parts. Before assembly, the parts were either dipped or anodized, essentially insulating one from the other. Consequently, they failed to make good contact at RF frequencies, which is essential for shielding. To bring the terminal unit into compliance, the following modifications were made: 1. Paint at the screw holes was removed to allow contact between the chassis bottom, middle and side sections. 2. The anodized oxide coating and paint were removed at points of contact between the cabinet shroud and chassis . Placing a copper filled elastomer at these interfaces provided a conductive, slightly compressible gasket. 3. The video connectors, which had been mounted on insulating washers, were grounded to the chassis at the point of entry to the terminal. 4 . Because they were picking up fields inside the terminal and reradiating them outside, all five keyboard leads were bypassed to the chassis at the point of exit with 100-pF disk capacitors. 5. Chomerics conductive shielding paint was applied to the cabinet's plastic shroud. Iterative tests showed the unit's emission to be well under FCC and VOE limits from 30 MHz to 1000 MHz.
Chomerics, 77 Dragon Court, Woburn , MA 01888.

JANUARY 1982 Digital Design 29

Load Module With Radio Frequency Filter At Input

208Y/120 V Power Source

_ _1_5 A Break-er_ __ _ _ _co_n_dui_t~-



Equipme~r;;;;;d"Cc;d;;;;Qr-- - - - -

Fault To Frame

120 v

-- -- ~_-w-

Grounds To Surroundings



Figure 2: Equipment ground conductor and conduit are for safety circuit breaker trips fault current. Earth grounds are not involved in

fault current path.


If some were connected to one ground rod and others

Technical details of techniques and their effectiveness are

connected to a separate ground rod . the noise which can be

beyond the scope of this description. It is a highly technical

expected between the two rods will create noise currents and

and complex subject on which books have been written and

voltages in the computer system and its interconnecting data

special seminars offered . There are military specifications in

cables. lt creates a ground loop.

great detai I.

Even if all ground conductors come together at one point

Shielding performs its function in at least three major

which in tum is connected to a single earth ground rod. the

modes. First. it serves as a terminal for electrostatic coupling

high impedance at high frequencies of long conductors can

with another conducting body at a different potential. When

interfere with the ground potential equalization which is

interposed between the external body and the circuits which

desired . Noise currents which flow and which create voltage

it protects. the a-c currents induced through the stray capaci-

drops in ground conductors often originate in the computer or

tance into the shield flow through the shield rather than

controller circuits (self generated) or may be capacitively or

through the protected circuits. This is effective at inter-

inductively coupled from nearby interference sources.

mediate and low frequencies. At high frequencies where the

The maximum length of a wire which can effectively

shield itself may resonate or where cracks or openings in the

equalize voltage differences between its extremities is l/lOth

enclosure admit specific noise frequencies. the problem

to I/20th of a wavelength. At high frequencies. travelling

requires special treatment.

waves of voltage and current reflect from the extremities . At

Second. electromagnetic alternating fields induce currents

specific frequencies. resonances occur where successive

in any conducting material. The induced currents are created

voltage waves coincide with the reflection of the previous

in such a pattern as to try to neutralize the magnetic field

waves. At resonance. the impedance of the conductor ap-

which created them . Eddy current shielding depends on high

pears to become very high and approaches infinity except for

conductivity provided by such metals as copper. aluminum

losses in the conductor and through electromagnetic radia-

and silver. and on thickness . Steel has much lower conduc-

tion as a radio antenna. At partial resonance. the impedance

tivity. but can usually provide ample thickness.

becomes too high to be an effective conductor for voltage equalizing purposes.

Third. magnetic fields can be steered around circuits by magnetic materials in the form of shields: electrical steel.


Note that a resonant conductor will not only radiate

permalloy. ferrite.

energy. but can also receive energy from nearby sources

Shielding through eddy currents and magnetic properties


which emit at the same resonant frequency . A nearby taxi radio transmitter. for example. may induce as much as

does not depend upon grounding. but are traditionally grounded to avoid shock hazard and to simultaneously take


several hundred volts into a conductor of the proper length

advantage of electrostatic shielding properties of the material

and orientation. If this is intended to serve as a voltage

selected .

equalizing conductor. it may do so only at low frequencies and at a few discrete high frequencies which represent " anti-

noise transmission and suppression principles

resonance. ''

In describing the four basic functions of grounding. a number

More will be said about improvements to ground potential

of basic principles and their applications have already been

equalizing conductors under the description of transmission and suppression principles.

described. However these do not fully explain how high frequency noise can pass through or around grounded and


Shielding. Grounded metallic enclosures. conduits and

shielded parts of systems.

flexible metal wire braid surrounding conductors and elec-

A voltage impulse applied to one end or. as a matter of

tronic components shield them from external fields. Shield-

fact. anywhere on a conductor. cannot reach the other end

ing effectiveness varies with frequency. metal thickness.

instantly. Depending upon the geometry and the insulation

conductivity and above all. geometry of the system .

dielectric between the conductor and the return path. elec-

30 Digital Design JANUARY 1982

trostatic fields and magnetic fields are created as the voltage wave moves toward the receiving end(s).
The energy in this voltage impulse wave does not exist in the cond uctor. The energy exists completely outside in the space between and around the conductor and its return path . It exists in the form of electrostatic fields between the conductors and magnetic fields around them .
In stead of energy flowing through the wires . a physicist wi ll rightfully proclaim that the wires merely guide the field. Moreover. there is no such thing as current flowing through a conductor into a ground rod without a return path somewhere . A ll electric ity flows in complete circuits . To be spec ifi c. if noise curre nt is being detected in a ground conductor attached to a ground rod. whatever is flowing into the ground is returnir.g somewhere else. Sometimes it is useful to find out what that ""somewhere else" is . The magnetic field and capac iti ve field whic h contain the signal energy or noise energy are the result of current in a conductor and its return path .
Because conductor paths have distributed inductance and stray capacitance. these govern the propagation velocity of a traveling voltage and current wave. Typical velocities are 0.5 to 0.9 the speed of light. about 6-10 in.Ins (500 to 850 ft./µ,s).
These may seem of academic interest on ly until one realizes that computer and controller circu its typically operate at 10 Mbits/sec or greater . If the frequency of the signal we re only 10 MHz. the velocity of wave propagation would cafl)' it typicall y only 85' during one complete cycle of the alternating voltage. As mentioned before. resonance effects of reflected waves affect the ability of a conductor to carry current without having it returned . To be effective as voltage diffference equalizers, ground conductors carrying 10 MHz noise signals should be no lo nger than l/ 10th or I/20th of a wavelength. or no longer than 8.5' to 4.5'. If and when

Term inal

Coiled Extension Cord Acts As A "Balun"

Communication Cable

~%% .../'"°'_ :z :zzzz;z:z %21
Figure 3: Common mode ground noise current can be reduced by the inductance of a coiled cord.
exceeded. the effectiveness of the conductor for equal izing vo ltage differences disappears. However. the conductor will sti ll provide the safety functions oflimiting touch vo ltage and enabling gro und fau lt protection to perform properly.
In practice. traveling waves are difficult to absorb: unless impedances are carefu ll y matched to that of the transmission characteristics of the conductors at their termination. the energy wi ll be reflected or diverted. In the general case. there will be some absorption and some reflected or diverted energy.

Grounding and Noise Terminology

The IEEE Standard Dictionary of Electrical and Elec-

Ground plane

tronic Terms gives more than four pages of definitions devoted to grounding. A few of the many which are relevant to this discussion are as follows:

1. transmission and distribution: An assumed plane of true ground or zero potential. See also: direct stroke protection.

Ground (earth)
1. electric system: A conducting connection, whether intentional or accidental, by which an electric circuit or equipment is connected to earth, or to some conducting body of relatively large extent that serves in place of the earth. Note: It is used for establishing

2. electromagnetic compatibility: A conducting surface or plate used as a common reference point for circuit returns and electric or signal potentials. 3. antenna: A conducting or reflecting plane functioning to image a radiating structure. Syn: imaging plane.

and maintaining the potential of the earth (or the

Some of the noise definitions are also relevant here:

conducting body) or approximately that potential, on

conductors connected to it, and for conducting ground

Electrical noise (control systems)


current to and from the earth (or the conducting body) .

Unwanted electrical signals, which produce un-

2. transmission path :

desirable effects in the circuits of control systems in

A. A direct conducting connection to the earth or

which they occur.

body of water that is a part thereof.

B. A conducting connection to a structure that


serves a function similar to that of an earth ground

(that is, a structure such as a frame of an air, space or

1. general: Unwanted disturbances superimposed

land vehicle that is not connected to earth).

upon a useful signal that tend to obscure its infor-


Ground bus (electrical system)

mation content. 2. general: An undesired disturbance within the useful

A bus to which the grounds from individual pieces of

frequency band . Note: Undesired disturbances within

equipment are connected, and that, in turn, is con-

the useful frequency band produced by other services

nected to ground at one or more points. See: ground.

may be called interference.

JANUARY 1982 Digital Design 31

common mode vs normal mode propagation
The normal mode of voltage utilization is the voltage which exists between pairs of power or signal conductors. For example. a light bulb uses the 120V which appears between line and neutral conductors . The light bulb is not affected by the voltage which may exist between either of these power wires and some local ground reference point. Normal mode is also called "transverse mode."
The common mode voltage is generally noise voltage which appears equally and in phase from each power or signal conductor to "ground." This may vary depending upon what is used for "ground" reference. In a system where there may be signal differences between parts of an interconnected grounding conductor network. there may be some differences of opinion of what the common mode voltage might be.
In many instances. it can be possible to select a ground reference point which has a minimum common mode voltage with respect to the circuit of interest. especially if the ground reference point and the circuit of interest can be interconnected by a very short conductor. To accomplish this. isolating devices are sometimes necessary to avoid creating paths for noise currents to flow and electromagnetic fields around those paths which can couple into sensitive circuits .
Common mode noise may be caused by one or more of the following: · Electrostatic induction. With equal capacitance between each of the signal wires and surroundings. the noise voltages and currents developed will be the same on both signal wires. · Electromagnetic induction. With magnetic fields linking both wires equally. the noise signals developed in each wire will be the same.
In practice. there is rarely a pure. perfectly balanced common mode noise or signal. There is more often a component of commori mode and another component of normal mode noise or signal. Unless circuits are extraordinarily well-balanced. one will convert some of its energy to the other mode.
A frequent source of combined mode and normal mode noise is the result of momentary impulse voltage differences between parts of a system which have different ground references . If the two systems are interconnected by a signal path in which one of the conductors is grounded at each end. the ground offset voltage impulse will create a current in the grounded conductor. As this current propagates. its distributed inductance and capacitance induces a similar voltage in the closely coupled return wire.
A longitudinal transformer called a "balun" can absorb the voltage difference and reduce the longitudinal current considerably while preserving the normal mode signal relationships between wire pairs and between each of the pair and a shield.
When interconnecting signal cables between systems having different ground references are very short. one balun between them may be sufficient. If the distances become longer such that the capacitance between the conductors or their shield and surroundings becomes significant. a balun at each end becomes appropriate. For still longer cables where the surroundings may not always be at the same potential. multiple baluns may be required .
grounding and noise control guidelines
Here are some applications of basic principles to corrective measures: · Comply with safety code requirements: safety first.
32 Digital Design JANUARY 1982

L1 L2G

L1 L2G

Shield L1 L2 GND

Typical for Magnetics Inc.

Core No. C-42206-TC

(Burroughs Part No. 1952 C-417)

(Used at Pasadena Plant)

L 1 ; signal lead

L2 ; logic ground

G ; shield and

Sh ield

frame ground .


000 000 000 000 000 000 000

00 00 00 00 00
00 00 00


Multi Line

Control UR Data Communications


Proc essor

To closest computer

ground conductor or

Keep th is conductor

signal references grid.

short and straight -'-c:::!:S~~>

., Figure 4: Suggested technique for installing baluns in data-
comm lines (direct-connected). There will normally be one line per balun. However, if several remote terminals are located in a common location with common power source and grounding (not more than 50' apart), more than one line may share a common core. This is on the assumption that the grund voltage offset (voltage between remote ground and computer room ground, both steady state and impulse) will be the same for all units in a single remote location with respect to the computer system ground. The number of lines which can be accommodated with one core depends upon the core window and cross-section dimensions. Sufficient turns to give 300 to 500 µh at very high frequency are needed.

However. do so in a manner which will also control or reduce

potential noise.

· Use dedicated power feeders and if possible. also dedi-

cated transformers for critical loads. Do not allow other

non-essential or power disturbing loads to share the same power feeder and associated ground conductors other than a


single common grounding point. · Place the critical system's central grounding point for


power and data communications or critical control circuits as

close as possible to it. In order for the power source to be

grounded at the same point. this requires an isolation trans-

former at the grounding point.

· If the critical load is spread out over a significant area with

distances of 30' or more for high data rate cables. provide the

system with a signal reference grid. This is a sheet of copper

foil. a mesh of bonded copper wires. or a suitably bonded

supporting steel structure for a raised floor (typically 2' by 2'


square modular panels. supported by stanchions at the comers. and braced with bolted-down stringers which cross brace and


provide an electrically continuous signal reference grid) .

The impedance of the foil or grid at high frequencies is

much lower than single conductors and has fewer resonant

frequencies in the desired signal frequency range. Connect-

ing the frames of computer units of a system to the reference grid under the entire system will do much to keep the ground voltage differences between units at a minimum.
The signal reference grid is to be treated as a system component which is grounded to the same system grounding point as the frames of other system components.
The signal reference grid must never be used as a replacement for the equipment ground conductors required by safety codes. The grid should be used to supplement the normal grounding means and used as an addition to. rather than a replacement for. equipment ground conductors run with the power conductors.
Placing a power center with isolating transformer on the reference grid allows the secondary derived voltage to be grounded at the transformer to the reference grid. This. in turn. is connected to the nearest qualified ground in the surroundings. plus a connection to the principal electrical ground for the building via the input power conduit and ground conductor at the building service entrance equipment ground. · Multiple power sources may be used to supply a critical computer load. if the power source grounds have no voltage differences between them. Unless both power sources originate at the same place (within. say 10' of each other) . voltage impulses and high frequency voltages can easily exist between the two sets of power conductors. simply because their ground references are not the same .

Use of isolating transformers at the critical load. placed close together with secondary neutrals grounded at the same point or to a common underlying signal reference plane. will greatly reduce the possibility of common mode voltage differences. This reduction can be made even greater through the use of transformers which have a shield between primary and secondary windings. Such transformers cost 10 to 15% more than unshielded transformers and are used by manufacturers of power centers for computer rooms.
It is feasible to supply part of a critical load with uninterruptible power and part with regular utility power, provided that their ground reference voltages never differ from each other or from the critical computer system grounding point by an amount which the system units can tolerate. This may vary from less than lOV to more than l ,OOOV. The use of isolating transformers in the computer room is a good solution to this problem.
· Bypass circuits , both primary and secondary (primary =
automatic bypass which is part of the UPS: secondary = external manual bypass for use when UPS bypass is to be serviced or replaced without having to shut down the critical load), should each make use of the same isolation transformer(s) in or next to the critical load as is used between the UPS and critical load. The apparent power source grounding point should not change as the power source is changed.
This can be accomplished by making the UPS input and output voltage t,Pe same so that its bypass and any other
r~E E. f [U,I ~·; \ITT: f1t.

Computer System

5983 r.1;i-_r.n Cove et I~ e ,;\a t~ 40

Building Ground-

ing Point.


G 3

(A) Star-connected "green-wire" grounding of system unit frames.


Computer System Building Ground·

ing Point .

4 Schematic

, c ----~B



3 4

Perspective (B) Star-connected green-wire grounding with supplementary broadband reference grid connected in parallel with safety grounding .
Figure 5: In these drawings "1" through "4" are typical computer system modules, and "5" is a "green wire" safety ground conductor for the floor structure.
JANUARY 1982 Digital Design 33


.. 500
. .Er.
2 100
..... - ics:
a'c"l. .5 10 "~ '
f,,. c"5!'



, , 'I


,,, I ,, I



,,,..., \


, ..../ '\ / Mean

"", / ,-~ Min

.II.. ...,J .... ,, I


I "



0 .02 0.1

10 30

Frequency (MHz)

control or power conductors without materially affecting the normal or transverse mode of voltage or current in wire pairs .
With baluns inserted to increase common mode impedance of signal interconnections, a shunt path for ground current to flow between the two grounded systems is needed to help equalize their voltage differences and further reduce the noise current which might otherwise flow in the signal cables . · Make a practice of pairing conductors so that the circuit wire and its return path will always be together. This minimizes the area between conductors and the magnetic field which it either creates or intercepts to pick up noise . A ground conductor should also be included with each signal pair when ground is not one of the pair so that the same

(A) Typical power source impedances (CBEMA) ESC-SC5 Committee)

principle will apply to common mode noise generation and noise pickup.

If there are multiple, parallel ground paths provided as

alternatives for signal return current, at high frequencies, the




.2 300



Ccl.>. .~


~ ·~

(B) Impedance of Ground Wire:
22' of 14 AWG Conductor is
at free end.

lowest impedance path with the smallest loop area between it and the outgoing path will carry the most current. This supports the practice of pairing signal wires with separate ground conductors, even though the ground conductors may be interconnected. · Signal wire cables lying upon a subfloor in a computer room can pick up noise signal voltages by capacitive or inductive coupling with other surrounding .structural steel and conductors. The reinforcing steel bars or wire mesh in

'ct:l 100

the concrete is only one of these. At the system central grounding point, connection should
be made with the building steel wherever possible. If the reinforcing steel or mesh is inaccessible, a 4' x 4' sheet of






conducting metal such as copper, aluminum or galvanized

Frequency (MHz)

steel may be placed directly upon the concrete subfloor and

connected electrically to the system central grounding point.

Capacitance between the plate and the reinforcing will pro-

vide a bypass current path, reduce the voltage difference and

1 /4 wave 1/2 wave 3/4 wave full wave

reduce coupling into the underfloor cables . This arrangement

is known as a "Transient Trap.··


· Review and plan the underfloor cable routing to provide

the maximum isolation between circuits which can carry

disturbances and those which can be disturbed.

Figure 6: Power source impedance, Z, is plotted as a function of

Avoid parallel , nearby runs in which both electromagnetic

frequency; ground wire impedance, for a fixed length,

and capacitive coupling will occur.


approaches infinity at 1/4, 3/4, 1-1/4, 1-3/4, ...wavelengths.

If one set of conductors must cross another, the possible

bypass do not need another transformer to step down the

intercoupling will be minimized if they cross at right angles

voltage . Voltage step-down, ifrequired, should be done close

to the computer room - preferably, in the computer room.

Ideal arrangement is 480V input and output at the UPS and



its bypass circuits. Stepdown to final utilization voltage is

accomplished at the computer room in a shielded. isolating transformer in a computer room power center. · Interconnections between very large systems require a slightly modified approach. Each system with its own grounding reference conductor system may have a voltage difference with respect to the other. This may be a continuous a-c voltage difference or may be random impulse voltage differences.
Acknowledging that two acceptably grounded systems

2 is 100
.§ 50

.......-Grounded by Green Wire Only
Grounded by Green Wire and Straps to
Signal Reference Grid

have voltage differences between them is the basis for pre-

dicting that noise currents will flow in any conductors which interconnect these separate grounds . An objective is to keep such noise current from flowing in any data cable interconnections.








Frequency (MHz)


Longitudinal transformers (also called "baluns ·· and "coaxers") can be used to increase the common mode impedance between the ends of communications. digital

Figure 7: Cabinet-to-ground impedance is plotted as a function of frequency. Logic and power cables are attached in this typical multi-cabinet computer system.

34 Digital Design JANUARY 1982



v480 XFMR 208Y /120 V By-pass

Computer Room

Distribution Panel

,;;;;;;~p.~-.1 _,~,gh Po~' ....

. .:.-""-""'-·.__ -. _


Ground # 2


Connections, Load is Grounded At # 1 and/or #2.

480 v

Optional Secondary By-pass at 480 V

_____ (Relocate XFMR)



L ___ _JPrimary


Rectifier By-pass


Computer Room Power Center(s) With Distribution

Figure 8: Locating the transformer close to the computer shortens ground conductors. It also provides other advantages. (A) conventional UPS configuration with XFMR in by-pass results in multiple grounds at a distance from computer. (B) Moving the XFMR to computer room shortens grounding conductors, simplifies installation and lowers cost of power conductors and switches. Optional secondary bypass (manual operation only) allows power to be removed from the entire UPS for service or replacement without computer shutdown.

and they are separated instead of lying one upon the other.

Lightning arrestors do not belong in the computer room.

· Be particularly aware of the possibility of interference

They belong on utility poles and on the input high voltage

from conductors which extend outside of the computer area .

winding side of transformers (above 4 .000V , typically).

These include refrigerant pipes. water pipes . fire alarm or

They belong outside of the buildings or just inside the

water detector circuits and conduit, fire extinguishing system

buildings they are intended to protect.

pipes and control wires, and both power and control wires for

The distance between the service entrance and the load

heating. ventilation and air conditioning. In addition, there

point within the building helps to attenuate residual voltage

may be metallic air ducts .

impulses.which lightning arrestors (diverters) fail to handle.

In many instances, the pipes and ducts can be installed

At the load, surge arrestors and surge absorbing capacitors

with an insulating joint. This allows the portion under the

may be appropriate. but closely coordinated with the recom-

computer critical load to be grounded to the computer system

mended isolating transformer, shield between windings, life-

rather than to be a continuation of a virtual antenna extending

safety wiring, communications circuits and any other con-

outside the area. An example might be a coolant pipe from a

ducting interfaces between the computer system central

penthouse on the roof which is exposed to lightning as well as

grounding point and surroundings.

being closely coupled to elevator and other equipment or

· Remember that the energy of a voltage surge impulse lies

neon signs which often create substantial radio frequency

outside the conductors which represent the source and return


path of the pulse . One of these may be the ground conductor

Where insulating joints in electrical conduit would violate

to the nearest earth ground rather than the conduit or equip-

safety code compliance, the insulating joints need not be

ment ground contained within it. The electromagnetic field

installed if the conduit enters the computer area at the same

created by this loop will induce voltages and currents in other

point where the principal power input to a computer enters

nearby conductors depending upon their proximity and ori-

the area. They can be bonded together and to the computer

entation. It is possible to arrange the conductors to minimize


system central grounding point. all at one point. This avoids

unwanted intercoupling from such surge impulses.

the possibility of noise currents being injected into the computer system signal reference grid or into separate units of a

· Ground conduction paths to drain static electricity need not be low resistance, but must not exceed 109 ohms to be

total system through the creation of ground loops .

effective (l ,000 megohms). To control static electricity , the

The advantages of a single point ground connection with

following may be effective:

external grounds are achieved more easily when the life-

1. Keep relative humidity above 40% (50% is ideal: 40 to


safety indicators. controls and wiring are coordinated with the power for the critical load in a common enclosure or through a closely located and interconnected junction box so

60% range, OK) . 2. Specify hard surface floor coverings with no greater than
o 109 ohms per square resistivity and not greater than 1 9 ohms

as to provide a minimum of voltage difference between their

to a grounded supporting structure such as concrete or raised

respective "grounds"'.

floor structure . Pressure laminates are made for computer

· When providing surge arrestors which clip or bypass surge

rooms to meet this requirement.

impulse voltages of significant magnitude (typically 250V or

3. If carpeting is to be used. specify that the propensity for

more on a I20V a-c line or IOV or more on a SY signal line).

static electricity generation by walking upon the carpeting

remember that traveling voltage or current impulse waves

wi II not exceed 2 ,OOOV at 40% relative humidity .

cannot be absorbed by such devices. Most of the energy will

4. Exercise some control over occupants" footware and

be reflected or diverted to another path provided for the

clothing. Some shoes with crepe rubber soles , for example.


will generate static when walking on a steel floor, and much

If reflected, the voltage will try to approach double ampli-

more on a carpet or pressure laminate floor. Clothing can

tude when it reaches an open circuit wire termination , or

often be treated with anti-static products during laundry .


impedance which is higher than the surge impedance of the

Nylon may still give problems.

incoming line . A shunt with a long conductor to " ground""

5. Avoid furniture with plastic upholstery or other fabrics

will have a high impedance and will most likely do very little

which cannot be treated to reduce static problems .

to attenuate the impulse amplitude. However. it may reduce

6 . Use anti-static mats. with or without grounding conductor

the total strength of the impulse by draining energy some

in work areas with static problems . Ground the mats in high

time later in the pulse if it has a long duration .

traffic areas .


JANUARY 1982 Digital Design 35

Survival In


Marketplace byLes Wellington

how to select

Compatible computer product manufacturers come and go with almost lightning regularity. We will provide some guidelines on how to avoid undesirable side effects.

compatible computer
products and vendors

reasons for failure
The short-lived nature of many compatible product firms is due to several reasons. The most common include: (1) their product is ill-conceived. (2) the product life span is limited.

(3) the cost is too high. (4) dependability and service is

limited and/or non-existent. There are more reasons why a

vendor goes out of business . not the least of which is that the

customer has become increasingly sophisticated about his

C ompatibility is the game today within the increasingly competitive computer industry; particularly among companies that manufacture hardware and software which complement the major manufacturers' computers.

computer system . Customers are more selective today . and this affects firms .
No longer will customers tolerate equipment that fails to meet their specific needs. or perform exactly as they want it to . They do not want to be limited to one specific computer or component supplier: if they can't get a part quickly from one

The marketplace for developing compatible

company. they want to get it from another and know it will

equipment is wide open. DEC, for example, offers

work just as well. They want flexibility in the performance of

one of the largest selections of computers on the

their computer and for it to grow as their needs expand.

market today; and, because of this popularity,

Customers also want equipment that is easy to use. does more than earlier models. and costs less to purchase and operate.

DEC has acquired a considerable following of
manufacturers who produce products designed

Above all. they expect any product they use to be dependably supported.


to improve DEC computer performance.

Choosing a company that has the capability to satisfy these

customer requirements is not si mple. There are many firms


who supply peripheral devices and add-on options for DEC.


And since the current marketplace offers a sales potential

estimated at half-a-billion dollars annually. more vendors


keep popping up. But which do you safely choose?

Few firms have a good track record of designing and

building successful products that are compatible: and those

that do. compete for the lion's share of the marketplace.

Those that fail to meet systems performance margins do not


remain in the marketplace very long . Product longevity . therefore. along with product reliabil-


ity. plus availability. ease of installation and service after

point-of-sale. have a great deal to do with a vendor's success

and a customer's sati sfaction . These criteria separate new-


comers and hanger-ons from the few successful companies.

36 Digital Design JANUARY 1982

Les Wellington is Vice President and Director of Engineering at Able Computer. 175 I Langley Ave. Irvine. CA 92714.

what does DEC compatibility mean?

Compatibility Check List

If you're talking hardware. you're talking about signal compatibility. its functional capabilities and its physical packaging - does it fit into the existing package" To be


Check Product Product




Important Provides Provides

software compatible the product must operate under DEC diagnostic programs and operating system software.
Each of these criteria is constantly changing due to new in novat io ns wit hin the industry. About five years ago. fo r examp le. the µ.P was in its infancy and looking for a direction to grow. Today. the µ.P is used extensively because of the

Si ze Space Required Accessories Included (e.g., cables,
mounting hardware)


many factors that make it superior to early computer concepts. T he µ. P did n 't pop into existence because one day an



engineer wanted one. It came into existence because the customer had a need for one. And once the bugs were worked out. the µ. P improved the cost-perfom1ance ratio. It required fewer boards. it used less space and consumed less power. It was easier to manufacture and provided added nexibility to a computer because it added more features that customers

Operating Temperature

Tolerance Range

Storage Temperature

Tolerance Range

Relative Humidity Tolerance Range



wanted . The bottom line to a vendor's success. therefore. is listen-
ing to what the customer wants . Vendors who don't pay attention to this are not long for this industry. because when



Signal Compatibil ity Connector Pin Compatibility Power Consumed

push comes to shove. the customer wi ll turn to another vendor.

Bus Loading Requirements Battery Back -up



The respons ive add-on vendors. who fi ll a 5% to 15% void

(which mainframe manufacturers cannot fill). can provide so lu tions to a specific market area because they are small and



can move q uickly without the sometimes cumbersome respons ibilities that inhibit the reaction time of larger companies. This capability helps them maintain a hold on this portion of the marketplace and permits them to provide real

Compatible with Manufacturer's Diagnostics
Compatible with My System S o f t w a re

alternatives for DEC customers.



today's selections


Most customers today are more mature in their attitude toward the use of computers. and therefore prefer keeping the system they have. expanding its power and capabilities as their growth dictates .
Expanding a system. however. reaches a limit when the

Operating Parameters (e.g ., baud rates ,
full/half duplex)

I i

mainframe manufacturer stops offering new products to

Opt ions


support a current line in order to make way for a new

(e.g., memory parity,

ge neration of computers . W hen a user's needs grow and his

modern control~

system cannot. add-in vendors can provide solutions to

extend the life of the current computer. They can provide

users the alternative of getting more out of the system they

already have. so that they can postpone moving up to the

next-generation computer. In selecting products from add- in vendors . the user should
be certa in that compat ibility is maintained in the areas that are important to him . Figure I lists areas of compatibility that might be evaluated in the purchase of an add-in product. Although not all areas are important to every user. it is important to have taken each into consideration prior to

Figure 1: Add-in vendors provide solutions to extend the life of a user's current computer. This Compatibility Check List shows areas that might be evaluated in purchasing an add-in product. The user should be certain that compatibility is maintained in the areas that are important to him.
a device controller. This allows the more complicated disk controller design to be standard for all their systems.

purchase. For vendors to produce viable products. they must con-

While this satisfies their needs for the design. manufacture and support of mass storage subsystems. the manufacturing

sider several variables. The product must rate favorably in

cost is increased due to the physical separation of the hard-

price. product life. space. bus loading. power required .

ware. By attacking one segment. the add-in vendors can

software compatibility. performance increase and anti-

create a one-board interface for one computer resulting in a

cipated volume.

cost-and space-effective alternative.


One large area of add-in vendor activity is mass storage. DEC chose a modular approach to disk subsystem design

To the vendor. there is the added benefit that if he has chosen to use a µ.P design . he can provide controllers for

which allows them to maintain a degree of component

other drives by simply changing the firmware . This contri-

commonality with all their computers. In one approach. they

butes to high maintainability and reliability for the customer.

designed a bus adaptor with a unique interface for each of

as we ll as lower cost. It also means that customers are seeing

their major computer buses. and with a standard interface for

a larger selection of product availability than ever before.

JANUARY 1982 Digital Design 37

This results in more practical alternatives for growth both vertically and horizontally.
technical advances
There are many examples uf the impact of technical advances. In the memory marketplace. continuing advances in semiconductor memory density allows the design of memory products with more memory capacity in less space using less power. The add-in vendors - those with the proper technological credentials - can utilize this technology faster. thereby providing a product at lower cost with attractive delivery dates . This capability is attractive to the customer. who not only wants this type of capability. but expects and demands it when dealing with a vendor.
In the mass storage controller and communications areas. for example. µ.P-based architecture is the trend because physical requirements demand more capability and less space for a more cost-effective end product with greater flexibility . Purchase price is reduced by lower material and manufacturing costs through use of µ.Ps which reduce the number of components and PC boards .
To the customer. µ.P design means not only lower prices. but savings in space. power and bus loading burdens on their systems. In addition to emulation of compatible computer fuctions. µ.Ps also allow the addition of extra features such as self-test diagnostics and user-selected options.
Add-in vendors assist customers in conserving system space through the denser. more bus-oriented !Cs that are available today. and through use of the more sophisticated multilayer PC board designs. Multilayer printed wiring board technology has been around for several years and only recently has its cost benefit improved.
Historically. components were loosely populated on a printed wiring board. A product might have required multiple PC boards in a dedicated backplane . Today. because prices continue to rise. packaging plays a greater role in cost figures. So if a supplier can get more performance in a given area. it is worth his while in reducing cost as well as possibly significantly improving his MTBF.
today's market
In today's market. compatibility is multifaceted . To be lured away from a mainframe manufacturer. the customer must be assured of compatibility at all levels . Hardware must provide physical packaging compatibility. environmental compatibility. functional compatibility and electrical signals and connector pin equivalence. The hardware must also be compatible with the diagnostics and operating system software to provide an alternate choice to an OEM's product . This is often referred to as form. fit and function compatibility.
This all leads to one basic fact: unless the product is an ''exact" copy of the compatible computer design. 100% compatibility is impossible. However. this is rarely a problem since all responsible add-in vendors define what their products cannot do as well as what they can do. Theoretical differences in implementation of a product will generally not affect an installation and application. but it is wise to be certain that your specific needs are met by a product.
A supplier must be aware of these criteria to survive in thi s increasingly competitive marketplace. Building a good product is not enough. Service is a big responsibility for the manufacturer because problems occur with anyone's product. When a vendor cannot react to these problems and prove he is a professional. the customer will look for someone who is. Ideally . if a vendor listens to what the customer's wants and needs are. and accepts this input. he
38 Digital Design JANUARY 1982

has the potential to provide a superior product that fills a variety of customer needs.
By getting to know the needs of the market as completely as possible. the add-in vendor is on stronger footing in the design. production and support ofa high technology product. ( Or. at the minimum . a saleable product that is viable in today's marketplace .

a look at tomorrow

As the industry continues growing. attitudes continue

changing. Most companies do not want to be tied down to

just one supplier. They want alternatives. If they cannot buy

what they need from "Company A." they want the option of

buying from " Company B." and they want to know that

" B" is either software transparent or can supply software

that will interface with the equipme'nt they originally ob-

tained from "A".

This obviously develops more competition. and there will

be those who cannot compete. It also develops the need for

interchangeable components that fit the demands of more

than one computer producer.

Today's customer needs the ability to obtain whatever

storage devices. 1/0 devices. memory. hardcopy. video


terminals. interface equipment. communications options and

graphics equipment he requires so he can design the type of

computer system that best suits his business and personal


preferences. A customer understands this situation and will

ensure that such standardization . reliability and cost does

occur. A supplier/manufacturer who doesn ' t understand this

will not last.

This trend exists now. In the computer industry today you

will find a number of successful computer manufacturers and

add-on companies that provide equipment for various

computer systems. To select the best vendor. a customer

must develop a list of those vendors that best fit his needs. He

should find out what products are available and determine if

there is a wide variety of choices within those parameters. He

should also determine if there is a migration path leading

from a lower cost system to the anticipated "ultimate"

equipment. and if this migration is easily accomplished.

A customer entering the world of computers is provided a

new efficiency factor that greatly improves his ability to meet the fast pace of today's business. A properly implemented


computer system permits him to accelerate his business

without requiring large volumes of people operating at

breakneck speed to achieve the same amount of production

provided by one computer system.

With this new tool. a business can reallocate its human

resources into a more creative environment. while at the


same time improving working conditions for the work force.

Operating costs are also improved because of this redirection

of human talent and energies.

But although growth will continue to accelerate within the

computer industry and customer needs will continue to

increase as well. budgets may grow tighter. This will present

challenges to the add-in vendor to extend and utilize new


technology to meet these increased needs and capture a

portion of the market . It will become increasingly important

to successfully second guess computer makers ' directions in

finding solutions.

Vendors unable to keep pace with the new technology-


to meet the needs of the market - will gradually disappear. On the other hand. add-in vendors that can design and build


successful products based on customer needs will continue to

provide good alternative solutions for compatible computer

product customers .


s alphanumerics 2896

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Circle 9 on Reader Inquiry Card

JANUARY 1982 Digital Design


Raster Monitor Evaluation And Selection
application and

While there may be a few specialized applications which can justify the costs of a "custom-built" CRT, competitive pressures will force most system designers to take advantage of the economies offered by CRTs which have been optimized for the mass entertainment marketplace. Monitor manufacturers may be able to add valuable graphics-display enhancements (e.g., long-persistance phosphors, extended-life cathodes), but the fact remains that the cake under the frosting was originally designed for non-graphics applications. The monitor-selection process becomes , therefore, a matter of finding the closest fit to a design objective, with the certain knowledge that price performance tradeoffs will be required.

environment are

aspect ratio and orientation

pivotal to monitor

Until recently. raster graphics system designers have had exactly two choices in the selection of aspect ratios (display-


screen width divided by height) and orientation (horizontal or vertical) . They could choose either a 4:3 horizontal or a 3:4

vertical configuration. Rasters with any other aspect ratio,

A review of today's technical literature indicates an almost infinite range ofmonitor sizes, types,

including 1:1, would have to fit within the limits set by the available monitors.

and display capabilities. On closer examination, however, repetitive patterns become apparent,

CRT monitors with 5:4. 4:5, and other full-screen aspect ratios are now offered in a limited number of sizes and models, allowing us to generalize the raster selection to one

limiting the choice and forcing compromises

of three choices: a horizontal rectangle, a vertical rectangle,

which may require a reexamination of earlier design decisions.

or a square . Each has its place, depending on the application , and the selection of the most suitable configuration repre-


sents one of the most fundamental decisions a systems

designer has to make at the start of a design project. Display-

1:1 Aspect ratio

memory architecture, interface circuitry, and almost all of the other monitor evaluation parameters are , in fact, directly

impacted by this choice.

The dominant orientation has been. and will probably


continue to be, the horizontal display rectangle. It matches the panoramic view provided by the human binocular visual system and can therefore serve as a natural "window" on reality - as evidenced by the theatrical stage, motionpicture screen. painted landscape , engineering drawing , and


television picture.

Vertically oriented displays also have their antecedents in

the form of printed pages of text and the illustrations


designed to accompany text. Western typography is most legible and compact when it is organized into vertical

columns composed of short horizontal lines . (Long lines

require extra spacing for legibility. and this reduces the


number of words which can be contained on a page .)

Diagonal Screen Size
9" 12" 13" 16" 19" 20" 21" 23"

A (mm)
148 216 240 283 348 356 368 408

B (mm)
162 180 213 261 267 276 306

118 172 191 226 276 283 293 324

Square displays have their roots in the charting of scien-

tific and financial information. Given a choice. similar or


identical scales (coordinate lines or circular arcs) should

always be used to represent two or more variables. Any

departure from this convention incurs the risk of a visual

distortion of the data. From clocks to compasses to oscilloscopes. the square or circle within a square has remained a


basic display configuration.

This article is excerpted .from the Raster Graphics Hand-

Figure 1: Raster dimensions as functions of the monitor screen size.

book. written by the engineering staff at Conrac. 600 N . Rimsdale Ave. Covina . CA 91722 .

40 Digital Design JANUARY 1982

Aspect-ratio and orientation decisions depend , then , on

timing relationships. There is no increase, therefore , in the

the type of information being displayed. If the graphics

percentage of time taken up by the retrace strokes. In fact, the

consist of representational views. such as those created by a

shorter lines mean that the scanning speed is actually

computer-aided-design system, a conventional horizontal

reduced , increasing the luminance and reducing the required

orientation would normally be specified. If the displayed

monitor bandwidth. We will be using the centered-square

information consists primarily of text, or if the graphics are

configuration as our model raster in the following discus-

being designed to accompany text when reproduced in

sions on display size and resolution.

another form, a vertical orientation can make more effective use of the monitor screen. If charted data is being displayed,

screen size

the decision will often be to create a square raster in the center

CRT monitors are available with nominal screen diagonals

of a conventional, horizontally oriented monitor screen.

ranging from an inch to over 25". The selection of an appro-

raster-line orientation
There is no intrinsic reason why the raster on this conventional horizontal screen should consist of horizontal lines. The raster could be just as effectively "written" with vertical strokes. But this would result in a larger number of shorter lines - and a significant increase in the amount of time "wasted" by the need to return the electron beam to the starting edge before each line is traced . The horizontalhorizontal configuration minimizes the number of retrace strokes, allowing more time to scan the "active '' lines as a

priate monitor screen size becomes , therefore, another fundamental decision which the systems designer must make. Screen size affects the interaction with the operator, the perceived resolution of the display , the required bandwidth of the monitor and interface circuits, and ultimately the size (and cost) of the display memory. In the case of display memory, for example, there is no value in storing data for more pixels than can be displayed - or discerned - on the monitor screen.
Internally, a monitor CRT is a projection-type display device. The amount of information which can be theoretically

percentage of the fixed refresh interval . The electron beam can scan at a slower rate, increasing the luminance of the

projected onto the CRT faceplate remains constant, independent of screen size. The principal advantage to be gained

display because more power is being delivered per unit area. The instantaneous data rate is also lower, which reduces the

by increasing the size is a broader spatial distribution of the display detad . Conversely, small screen sizes tend to com-

required bandwidth of the interface and monitor circuits and

pact the image elements, with a likelihood of overlapping

the readout rate of the display memory.

and loss of information when a lower limit is exceeded.

AI I of these benefits accrue to a vertically oriented display

provided the raster lines are also scanned in a vertical

direction (i.e., by turning a conventional monitor on its side).

Such displays can be readily adapted to the generation of

images. but they would require major restructuring of the

text-oriented system architectures which could make max-

imum use of the vertical format. In most commercially

available vertical-monitor systems, therefore, the raster lines

are still scanned horizontally , from top to bottom.

The demands of this configuration on monitor perform-

ance can be impressive. One vertically oriented system, for

example, scans (and retraces) 800 short raster lines at a

full-frame refresh rate of 60 Hz . The horizontal-scan interval

is only 20 f.LSecs. of which 25% is taken up by the retrace

stroke . In order to display up to 8.000 characters on the

screen , pulse rise/fall times have been reduced to 4 nanosecs.

compared to a conventional 20 nanosecs. To provide this


response, monitor circuits have been designed with a 100-

MHz bandwidth- five to ten times the normal requirement.

A sq uare raster centered on a horizontally oriented screen

would nominally represent a midpoint between the horizontal

and vertical configurations. The raster lines are shorter, as in

the case of a vertical display. The number of lines remains the

same as those of a horizontal display. But these comparisons

are misleading. Customary practice is to "squeeze in" the sides of the raster without changing the horizontal-raster

Figure 2: Gaussian distribution of electron-beam spot luminance. (Source: Reference 1)

JANUARY 1982 Digital Design 41

individual pixels can no longer be readily perceived by the


Display resolution is determined almost entirely by

dimensional mathematics. A square raster with 512 raster

Equally spaced overlapping Gaussian

lines and 512 pixels per line contains a total of 262 , 144 pixels. Each pixel area is , in effect, a square with sides measuring approximately 0 .'002 of the raster height or width. When displayed on a 19" monitor, the pixels wou ld measure

Distance across CRT face

0.54 mm on each side. The same pixels on a 13" monitor would have side dimensions of only 0 .37 mm.

Figure 3: Effect of overlapping raster lines or pixel images. (Source: Reference 1)

The pixel images on the display screen are not, however, square. Instead, they are formed by an electron beam with, at best, a circular or slightly oval shape (depending on the

Ergonomic considerations suggest the use of the smallest

position of the beam relative to the center of the screen) .

screen size that will allow the required information to be

Moreover, the luminance generated by the beam has a

clearly "read" by the user. Small-screen luminances are

Gaussian distribution , as shown in Figure 2. It is inevitable,

generally higher, and the screen comes closer to matching the

then , that a certain amount of overlapping between pixel

operator' s field of maximum visual acuity. Small-screen

images will occur, especially if a further requirement is that

monitors also offer advantages in terms of economy, ease of

each pixel area is to be "filled" with display luminance.

packaging, and extended cathode life due to the lower

Overlapping is a benefit when images consist of solid areas

electron-beam current required for adequate display lumi-

or subtly changing intensities or colors. Figure 3 illustrates

nance. On the negative side, phosphor life may be signifi-

how a column of pixels can produce a relatively smooth

cantl y lower if the e lectron-beam density is elevated. With

luminous output across a group of raster lines . But the

the same electron-beam current in both cases, the useful life

Gaussian spread of the electron beam creates major problems

of a 9" monitor may be less than a fifth as long as that of a 20"

when sharp image transitions are required - as in the


extreme case when graphic elements are to be separated by a

Figure 1 indicates the maximum raster display areas obtainable on a range of monitor sizes. Monitor spec sheets

single pixel width . The Gaussian " skirts" of the pixels on each side would raise the luminance in the intervening area,


often give " picture" (i.e., television) dimensions which

reducing the contrast between image and background.

must be adjusted downward when. as is usually the case, all

four com ers of a graphics image must be clearly visible. The millimeter va lues given in Figure l are , on the average, 10% less than the usual spec-sheet dimensions . The square-raster values take advantage of the slightly oval shape of most monitor bezels and are 6% higher than the vertical dimensions for 4:3 rasters (this amounts to 15 mm for a 19" diagonal screen monitor.)
display resolution
" Resolution" has been defined by the number of pixels stored in display memory and transmitted to the monitor during each frame-refresh cycle . The bandwidth of the inter-



~ ~/ T·mP"""" ::6'

---==-======:::...J;ll~ Em1tt1ng


............--~ surfaces

1 ~1:n8:·::1-Cfhaimfbfer~w"i"th"

Molybdenum..Jlll"' Porous tungsten body #

reserve supply of

cylinder ~ ·

barium compound

face. for example. must be capable of preserving the

"system" resolution established by the number of pixel-topixel signal transitions which could occur while each raster line is scanned . The same bandwidth considerations apply to

Figure 5: Conventional cathode compared with extended life cathode. (Source: Reference 1)

the monitor circuits which process the display signal and

The loss of contrast from this effect is given a numerical

drive the electron gun (or guns) of the monitor CRT . It is

value by the "modulation transfer function" (MTF) - the

entirely possible. however. that a severe degradation in the

ratio between maximum small-area (pixel, raster line) and

system resolution can occur at the final display stage - if

large-area contrasts. [f there is no loss of contrast due to

overlapping, the MTF is 1.0, 100%, or zero dB. A 50%

contrast loss (-6 dB) is normally considered to be the limit

Critical angle

for adequate monitor performance . Larger losses in contrast

would have the effect of reducing the display resolution


because individual pixels would be difficult to distinguish -


even on close inspection. The MTF can be improved, of course, by reducing the spot

size of the electron beam. But this lowers the overall

luminance of the display and may make the raster lines too

distinguishable. A compromise is therefore required. Spot

sizes, measured at the diameter of 50% maximum lumi-

Aluminum backing


A-A 8-8 Halation ring

nance , are generally set to approx imately the same dimension as the raster-line spacing which wou ld be on the


order of 0.5 and 0.3 mm for the 19" and 13" monitors

Figure 4: Halation ring formed by reflections within glass faceplate. (Source: Reference 1)

described above. Smaller monitors would require correspond ingly smaller spot sizes to maintain an equivalent MTF,

42 Digital Design JANUARY 1982


Available in three configurations:

rack mount, and horizontal or vertical

desk type, the TMS can be positioned

to suit your system requirements.

Cost effective: no capstan; no

mechanical buffering. The TMS is an

easy-to-thread manual load device

and has only one PCBA.

Non-essentials were eliminated to

create a low cost, high speed, small

size, standard interface tape drive.

Easy on your checkbook. High in

The Ampex TMS Streamer type performance. And, in great demand

tape drive solves your problem of cost as the backup for Winchester drives.

effective Winchester backup. How?

For additional information on how

As a simplified tape subsystem it

you can get low cost of tape owner-

provides high on-the-fly throughput. ship, contact Larry Russell at Ampex,

It's two drives in one. In the

Memory Products Division, 200 N.

streaming mode it provides non-stop Nash St., El Segundo, CA 90245.


data save-and-restore. In the

(213) 640-0150.


start/stop mode, the TMS performs


traditional tape storage function. And

up to 40 megabytes of data can be


stored on a single reel of standard V2"

computer tape.

The Designers Choice.

Circle 11 on Reader Inquiry Card



Deflection Electrostatic

Focus Electrostatic







Charact·istics High Speed Moderate Resolution Moderate to High Resolution
Highest Resolution

Application Oscilloscope
Television Computer Graphics Projection Recording
Not Generally Employed

450 To 500 700 To 900 1600 To 2000

Figure 6: Electrostatic and electromagnetic deflection focus trade-offs. (Source: Reference 1)

and this eventually sets one of the lower limits on the extent

shade the screen from overhead light sources.

to which the screen size can be reduced and still produce a crisp, high-resolution display. With 0.2 mm as a practical

monitor enhancements

lower limit on spot size, the minimum square-raster dimensions for a 512-by-512 display would be on the order of 100 mm. For a 1024-by-1024 display, the minimum would be 200 mm - requiring at least a 13" monitor.

Both the CRT and the graphics-display CRT monitor are still evolving as commercial products. A variety of monitor enhancements should be evaluated, therefore, before a selection is made.

display filters

Many of these innovations relate to reliability and device life. The use of impregnated cathodes is an example. Every

Contributing to the MTF loss - and the potential loss of

CRT will eventually "bum out," just like any other electron

display resolution - are the diffusing effects of secondary-

tube. Figure 5 illustrates how a reserve supply of barium

electron emissions within the phosphor layer and the

compound can continuously refresh the surface of a porous

"halation" caused by reflections within the glass faceplate.

tungsten cathode, allowing the CRT to be driven at very high

Figure 4 shows how halation rings may form around each

current densities and still give thousands of hours of service.

pixel location, again reducing the effective display contrast.

Other enhancements relate more directly to performance

Fortunately, most of the steps taken to minimize the

and should be considered within the context of a specific

contrast-reducing effects of reflected ambient light - such

application. The conventional CRT electron gun, for

Monitors are analog devices, with all the uncertainties inherent in such components.

example. "crosses over"' the electron beam to give the focusing elements a point source. A parallel-flow design


increases the number of electrons directed at the CRT face-

plate without a corresponding increase in the cathode

"loading factor.·· Small spot sizes are somewhat more

difficult to achieve, so the technique represents a tradeoff

between luminance and resolution.

Similar tradeoffs apply to the choice of electrostatic or

as "etching" the faceplate or adding a filter-also lower the

electromagnetic focusing and deflection. Figure 6 indicates

amount of contrast loss due to halation. Etching acts by

that an al I-electrostatic design would be preferred for systems

diffusing the light at the glass-air interface. Normal practice

requiring very fast scanning rates and modest resolution (spot

is to bond a treated glass plate directly to the front surface of

size). An all-magnetic design reverses this order. Most

the CRT. The diffusing layer reduces the amount of light

raster-scan graphics monitors consequently use an electro-

reflected back toward the phosphor. The displayed image is

static-focus, electromagnetic-deflection combination which

also slightly diffused. so etching represents a tradeoff

represents a compromise between resolution and speed.

between two negative effects. Filters, eithe'f laminated to the faceplate or mounted
separately. act by simply absorbing a fraction of the light-

Manufacturers may also incorporate special circuitry into the design of the monitor itself. One example is a "beamcurrent feedback'" circuit which maintains the black level of

both wanted and unwanted. Luminance generated by halation tends to leave the surface at an oblique angle and therefore

the display at a constant value despite CRT aging and component drift. The CRT beam current is sampled during each


follows a longer path through the filter layer. The same

vertical retrace. Feedback adjustments are then made to the

would be true of oblique ambient light. In addition. reflected

DC level of the display-signal amplifier to correct for any

ambient light must pass through the filter twice and is consequently attenuated twice as much as light emitted by the phosphor layer. But again a tradeoff is involved. Filters reduce the display luminance and can also affect the display resolution.

detected error. CRT monitors are analog devices, subject to all the uncer-
tainties which affect the performance of such devices. Enhancements like the beam-current feedback circuit help to make the monitor a stable , dependable system component in

A variety of filtering materials and processes are commercially available. often combined with such anti-reflection

an otherwise digital environment.



measures as vacuum-deposited optical coatings. Polarizing

Figures 2-6 reprinted courtesy ofLawrence£. Tannas.from

layers have proved particularly effective. In one instance. the

Flat-Panel Displays, Van Nostrard Reinhold Co, New York,

"filter"' is actually an assembly of miniature louvres which

NY 1981.

44 Digital Design JANUARY 1982


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JANUARY 1982 Digital Design 45

Equipment Manufacturers Drive Data

by Dr. John W. Wilson
Eq uipment has emerged as the dri ving fo rce behind teleco mmunications. Unfo rtunately. term ino logy te nds to bias the de bate. Just as it is futile to wonder whether book publi shers are printers of books or producers of in fo rmation. it is even more di ffi cult to speculate whether eq ui pment manufacturers make products or produce systems that tra nsmit. process and distribute information.

computer-based equipment, and its hardware/software, today dominates telecommunications
T he world of modern telecommunications has been slow to acknowledge that equipment, not transmission facilities, has emerged as the central feature of the information age. Manufactured equipment has for too long been regarded as allied, associated, ancillary or peripheral. Even the terms "interconnect" and "customer premises equipment" convey the notion of lesser or incidental status. But, it is the transmission medium which is becoming increasingly incidental to intelligent equipment. If we fail to recognize this, the true benefits of the Information Age may not materialize.

information business confusion
Th ts sense of confus ion is best dramatized in a matri x of the '" In forma tion Business .. (Figure 1). It describes a ga laxy of so-ca ll ed info rmation products and services linked by ..condui ts .. of "content .. between the sender and receiver. Th is cosmos of products and services is then obscured (Figure 2) by a c lo ud . which masks the true meaning of the dependence of in fo rmation products and services on computer tec hnology.
Thi s simplistic fo rmulation ass umes a limited num ber of suppliers are now competing. or would li ke to compete. for the chance to furni sh consumers with a unitary .. info rmati o n" system . complete with products. voice and data process ing. tran smiss ion and information itself. It ignores the fac t that competiti ve markets do not function in th is manner and will not do so unless leg islation requires or stimul ates conditi ons which re info rce a monopo ly or generate an o li gopo ly (a situation in which each of a few products affects but does not control the market).
Any po licy which advances a system concept cannot ex pect to ma intain or ac hieve competiti ve diversity. At best. it w ill produce some degree of o ligopo listic market di vision betwee n giants such as AT&T and IBM . The control. or capac ity to gain cont rol. of transmi ss ion networks. combined w ith the economic power to vertically integrate so-called in formation products and services . will necessari ly limi t the number of competitors. as we ll as the amount of technical innovatio n.


Dr. John W. Wilson is president ofa research and consulting

f irm . J. W. Wilson & Associates, Washington, D .C . This

article is taken fro m Dr. Wilson's testimony before the

Subcommittee on Telecommunications, US House of

Representatives .

· ·

46 Digital Design JANUARY 1982

If the policy of competition is to be more than rhetoric. it must focus on distinctions between manufacturing and information services. Manufacturing includes: wire. telephones. PBXs. transmitter/receivers. modems. computers. digital data storage. data terminals. etc. Services include: various combinations of manufactured products used to provide services.
systems approach inadequate
Whether manufactured products can be used to provide diverse information services is largely irrelevant to the fact that di verse combinations of manufactured products are used to provide services.
The systems approach would have us look at printers. computers. data terminals. word processors. PBXs. telephones. controllers. multiplexers. and modems connected to telecommunications switching and transmission facilities interacting with controllers. multiplexers. modems. telephones. PBXs. computers. television sets and other terminals. as mere extensions of the telephone network . This view of an amorphous system masks the diversity of separate industries which are combined by the invisible hand of consumers creating their own information service capabilities. Thus. the information marketplace is not unitary. It relies instead on the existence of separate market sectors for innovation as well as supply.
There is the Computer Equipment Industry sector with its mainframes. minis. micros. data terminals. end-user periph-

erals and OEM peripherals . There is the Data Communications Equipment Industry sector with its controllers. multiplexers and modems. Then there is the Word Processing Equipment Industry sector. Third-generation products in this industry are capable of performing some functions of a minicomputer. Next there is the PBX and Telephone Instrument [ndustry which also includes key systems. These now include an increasing array of intelligent telephone sets and systems . And finally. there is the Network Switching and Transmission Equipment Industry . Taken together these di verse and discrete sectors create a synergy - not a system. They produce the potential for unlimited user selection - not unilateral supplier solutions.
an electronics-driven industry
Every one of these industry sectors is being driven by new generations of electronics. But dependence on electronics does not lessen the diversity of industrial opportunity. The fact that a company in one sector may cross over into another does not abridge their separation. Nor does it indicate any need for consolidation based on technological integration . Each. of course. has some need to use the transmission network. much in the way that each uses electricity. Yet. the common need for network facilities requires that no controlling entities be permitted to freeze out diverse. competitive access to that network.
Control of the network creates a potential conflict of interest with manufacturers dependent on the network. It

U.S. Mail

Telephone SCCs

Broadcast Networks

Professional SVCs

Parcel SVCs

Telegraph VANs

Cable Networks

News Services

Courier SVCs

Mailgram IRCs

Cable Operators Broadcast Stations Data Bases Teletext

Financial SVCs

Other Delivery SVCs

Multipoint Dist. SVCs

Advertising SVCs

Satellite SVCs FM Subcarriers

Time Sharing

Service Bureaus

Printing COs

On-Line Directories


Paging SVCs

Software SVCs

Industry Networks



Defense Telecom Syst<?ms

Security SVCs


Loose-Leaf SVCs



Software Packages


TV Sets

Printing and

Telephones Terminals

Telephone Switching Equip.


Graphics Equip.









Cash Registers





POS Equip. Antennas Fiber Optics Calculators

Multiplexers Text Editing Equip.



Typewriters Dictation Equip.

Word Processors

Communicating WPs

Phonos, VTRs, Video Disc

Audio Records And Tapes

File Cabinets

Microfilm Microfiche Mass Storage

Video Programs


Business Forms





ATM - Automated Teller Machines

SCC - SoecialiZP.d Common Center

IRC - International Record Center

VAN - Value Added Network

PABX - Private Automatic Branch Exchange VTR - Video Tape Recorder

POS - Point of Sale

WP - Word Processor
© 1980 By President and Fellows of Harvard College

Figure 1: This matrix of the "Information Business" plots products and services as a function of "conduits" of "content."

JANUARY 1982 Digital Design 47

creates an actual conflict of interest where the network supplier is. or may be. vertically integrated with a product manufacturing entity.
Looking at these separate industries. we find that. including AT&T and IBM. the total computer and communications equipment industry (excluding network. transrn1ss1on equipment. electrical components and semiconductors). generated revenues of$49 billion in 1980.
Total equipment revenues of$49 billion excludes network transmi ssion and central office switching. The market is as follows: data terminals, $4.9 billion; microcomputers. $0.7 billion ; minicomputers. $8.8 billion; mainframes. $15.2 billion: end user peripherals. $6.9 billion; OEM peripherals. $3.8 billion; WP. $0.9 billion; data communications equipment. $1.2 billion; and voice communications equipment. $6.6 billion. (The source for these figures is the Gartner Group and Trade Press).
The five largest components of these industries. and the ones most vulnerable to monopoly displacement. accounted for revenues of $42.4 billion in voice communications equipment. computer mainframes. minicomputers. data terminals and end-user peripherals. Within the Computer Equipment Industry. 1980 revenues reached $40.3 billion. averaging a growth rate of 32.5% over two years marked by recession . 1982 should be greater. The subrnarket for computer mainframes is the only sector where IBM achieves substantial monopoly dominance. However. healthy growth was recorded in all subrnarkets of the industry. as a variety of corporations developed and marketed products outside of IBM 's dominant market; and. so far. IBM has not been able to commandeer the industry's subrnarkets.
IBM has entered the WP and data communications industry sectors. but does not dominate them; and its role in the modern/multiplexer (data communications equipment) market is limited. AT&T is entering the data terminal equip-

ment subrnarket of the computer equipment industry and has traditionally held a major portion of other data communications equipment submarkets.
In the PBX and Telephone Instrument Industry. AT&T currently plays the predominant role. The total industry recorded $6.6 billion in revenues in 1980. Of the total industry. AT&T and independent telephone companies amassed revenues of $4 billion in the submarket for PBX equipment and $1.4 billion in the business telephone instrument submarket. In this market where carrier size and market power dominates. the asset value of PBX and telephone instruments owned by AT&T and independent telephone companies exceeds $12 billion. Their installed base. including PBX. surpasses 186 million telephone instruments. in both residential and business markets. In business telephone instruments. AT&T owns 47 .790.000 stations and 91 % of the market in relation to interconnect competitors . Competition in the PBX and business telephone submarkets of the PBX and Telephone Instrument Industry has only achieved a 9% hold 0.11 the market over the past eleven years of its existence.
computer II decision
Each of these industry sectors is shown to exhibit their competitive condition. They now face AT&T and independent telephone company entry under the FCC Computer II decision and legislative proposals surfacing since 1976. As that event occurs. legislative policy. if it is to be affirmatively competitive. must deal with cross subsidies. tying and conflicts inherent in the carrier ownership and control of the network. The FCC's Computer II decision. and current legislative proposals. wholly fail in this regard. Computer II is a sieve through which regulated service revenues flood freely.
Under the Computer II framework. there is not sufficient separation of deregulated activities from regulated services



Cable Operators

Cable Networks

Multipoint Dist

Satellites SVCs FM Subcarriers
Paging SVCs

Time Sharing Industry Networks

Data Bases Teletext
Service Bureaus O,n-Line Directories
Software SVCs



Software Packages

. t"i'

TV Sets



"O 0

Pr inters




Concentrators .



POS Equip.

Fiber Optics Word Processors

Text Editing Equip.


VTRs Video Disc

Communicating WPs



Mass Storage



Figure 2: New products and services from 1930 through 1980 show the inherent dependence upon computer technology. 48 Digital Design JANUARY 1982

to prevent capital cost subsidization. or the subsidization of marketing. research. manufacturing. installation and maintenance of products . Nor is there sufficient separation. or continued regulatory control. to prevent the manipulation of accounting systems which facilitate the shedding of product costs in manufacturing and distribution operations conducted by carriers. And the cross-subsidy cake is handsomely frosted with joint advertising and market image-building.
Carrier control of the network remains one of the single most critical barriers to terminal equipment competition with carrier manufactured or purchased products. Under Computer II there is no obligation to publish technical information of changes in the network. or to publish revised standards and protocols. before carrier furnished equipment is first distributed to the marketplace. As a consequence. independent manufacturers are prejudiced by the denial of lead time in which to modify their products to altered network interfacing requirements . The refusal to provide competitive manufacturers with network load and response data is a source of persistent conflict.
people problems
There are. in addition. operating company conflicts of interest that impede access to the network. These are people problems. Whatever a customer's equipment needs. carrier employees will certainly refer them to the marketing department of the telephone company's manufacturing or product marketing affiliate. Moreover. under Computer II and sundry legislative drafts. there are no proscriptions to inhibit the disincentives of telephone company employees to furnish quality network services to products developed and delivered by non-carrier suppliers . Competitors rarely enjoy

installation and service priorities comparable to those

assigned the product marketing arm of the telephone

company .

Because wages. advancement and pensions are tied to the

achievement of corporate objectives. carrier service person-

nel are all motivated to equate equipment sales losses to

competitors with personal economic harm.

Conflicting corporate interests arise through the preferred

knowledge carriers gain merely because of their network

ownership. For example. under the FCC's equipment regis-

tration program. carriers obtain a trove of marketing data on

each customer's equipment. whoever installs it. Such data is

readily used to retard the progress of competitors who. by

law. must provide it to the carrier.

These conflicts also impede the licensing and use of

patents. and facilitate the rotation of managerial and other

personnel having common knowledge of network functions

and product performance . In addition. all conflicts of

interests are hidden in the consolidation of financial and

accounting data for joint operations: and in joint operations


These innumerable conflicts grow from the advantage of

being both a provider of a bottleneck service and a supplier of

the equipment that utilizes that service - if there is anyone

else offering independently manufactured products per-

forming the same or similar functions. Moreover. such con-

flicts and barriers are inherent in any structure predicated on

the existence of a single corporate family simultaneously

involved in regulated and unregulated telecommunications

activities. equipment manufacturing and supply. The effect

of such a construct is to destroy the very competition it

purports to promote.


Model VRG·Q Add-In Graphics Memory for the Q-BUS

VIURAM video interfaces make your

0 0 0 0 0 0

512 x 512 x 1 Frame Buffer Parallel Character Memory Dual-Height Card Line-By-Line or Direct Addressing TEK 4010 Emulation Software Low Cost, Available Now

display 1/0 a natural extension of your computer software, not a choke point. Our direct-access display hardware, by avoiding cumbersome serial methods, provides maximum efficiency, fast character and pixel thruput, and extreme


Contact Tom Birchell at:
3014 Lakeshore Avenue Oakland, California 94610 (415) 465-9000 TVVX: 910-366 -2029

ease of software implementation.

Computer Technology Division

Circle 7 on Reader Inquiry Card

JA.l\IUARY 1982 Digital Design 49

--_Innovative Design- -

Tiny Core Memory Solves Big µP Problem

Microprocessors are widely used in low cost controllers for "smart" machines and process equipment. In these applications RAM chips provide low cost but volatile storage and leave designers with a major problem for real-time applications: how to deal with power outages resulting in total loss of stored data. with costly, or even life threatening consequences. A solution is to provide some nonvolatile memory to prompt an automatic restart capabi lity.
Core memories are ideal nonvolatile storage systems . and are widely used in large control applications, but tend to be more cost ly than volati le RAMs especially in very small capacities. It is often possible to design contro llers so that o nl y a few words. or even a few bits need be saved in nonvolatile storage . Typical data so stored may be manually entered set points. tool positions . program counter state, position

of moving e lements of a machine and process variab les such as temperature and flow .
CMOS RAMs with battery backup can provide nonvolatile storage, but the long term reliability of batteries, especially under wide range temperature cycling and frequent charge-discharge cyc les, is open to question. MNOS devices are another approach, but suf-
fer from slow write times. and a unique type of fatigue termed "endurance."
A s imple , low cost core module has been- developed by Controlex Corp. The first member of the fami ly, the 120. is a four bit module contained in a 14 pin DIP and supported by low cost TTL chips in simple circuitry. The core is of sq uare loop mag netic material similar to that used in conventional core memories, with windings in a unique geometry so as to all ow conventional TTL chips to provide the required drive

current. Thi s results in a simple interface to the host system .
Operation of the core module is initiated by clearing the cores with a READ operation. To clear the core, it is forced to the "O "' state by driving the set winding. Thi s provides a known initial condition for the WRITE operation to follow. To write data. the core is either left unchanged (write " O"" ) or fo rced to the opposite state (write " l ") by current in the reset winding.
The 120 is intended for sequential operation under software control of a µ.,P I/O port. A typical system is an e ight bit configuration using two 120 modules in cascade (Figure 1). To trace operation. ass ume that ·a READ operation has taken place. and that all
cores are in the "o·· state. This would
be done by driving R low for eight clock cycles. and switching address terms ABC through all eight combinations.

Clar-y J()kVA·TheiilentUVi

The Clary Corporation as a proven provider of reliable Uninterruptible Power Systems now has the quietest UPS of all. The 15kVA and .30kVA are so silent that they are a welcome addition to any computer room working environment. A Clary UPS protects sensitive computer systems in many applications such as telecommunications, security central stations, manufacturing process control, medical laboratories, business information systems and data processing. As an additional feature we can now supply a power distribution center to the UPS. UL listed File No. E68909 Models 12501, 2500-1, 5000-1, 5000-1/SBS, lOk-1, lOk1/SBS with 15kVA pending. The complete power solution is now the quietest solution. For more information, please call or write us.



~ 320 W. Clary Ave.. San Gabriel, California 91776 Phone (213) 287-6111 TWX 910-589-3369


50 Digital Design JANUARY 1982

Circle 15 on Reader Inquiry Card

To write. R is pulled high for eight
clock cycles. with ABC selecting all eight combinations. and data presented as desired for each address. The waveforms of Figure l show an alternating 1010.. pattern. For the next READ operation. core outputs will follow this pattern. with a 2V pulse generated at the sense output for each "l" output. This is sufficient to drive a transistor directly to shape the output for TTL compatibi lity. The switching time of the core is about lµ.s. allowing plenty of time to strobe the data back into the host system without latching .
An advantage of the sequential operation is that only one output line is required , and that low cost TTL decoder chips may be used directly for drivers . All timing is controlled by a single clock. which may be derived from the main system clock.
Many variations of the 120 are possible. and include both 8 and 16 bit units. as well as multiword (4 X8) and parallel output versions.
Controlex is now in production on the 120. with price in OEM quantity of $6.90 each.
Controlex Corp, 16005 Sherman Way, Van Nuys, CA 91406. Circle 197

Write Driver

A>---+...... A




c ~


1 of 8

Write 0
Write 1

A. 13

s~ 1-2_ _ _~

~---- 121 R1 N

~---1-01 R2
....--9--i R3


3 S1
S2 -5 - -..... 53 6



Read Driver
0 A
1 B

.__ _1_2-f R1 N S1 3

45 ",..'".. Read

6 7

D v

' - - -1-0-1 R2 ~ s2 i-5-- - - - ' ~---9-oR3 - S3 ~6 ---..J


TIS133 (or Equiv.)

...______. 4 .7K d""1.

-: 470
_ _..,wv.--. +5V

W Data Out
Figure 1: This tiny core memory application uses two 120-2 modules cascaded to provide nonvolatile storage. Write is accomplished by selecting 1 of 8 reset (R) lines under 1/0 port control of ABC address terms sequentially. Data=1 allows switching current to flow during clock time. Read is accomplished by pulsing clock for each of 8 cycles while scanning ABC address lines.

256 KD MOS MEMORY for LSl-11/23TM


' ,", -·,t j i -'..~

!: I 1", j-


:f 1 ' . '
: -I
: ,,.rinJ




J .,·. ~ ---:

i~ -J1-_'.

J ~:

· .·r~.
~-r-1 '
.) J .J

4M[3 Addressing Standard/Parity Option

for s1200.00

Mini-disk speed, capacity and reliability for only $399.50.



2670 Walnut Avenue I Suite C
Tustin, CA 92680

(714) 730-7207

Circle 21 on Reader Inquiry Card

· Standard RS-232C communications link · Built-in operating system · Two file management structures: ASCII and binary · Three baud rates available: 300, 1200 and 9600 · Busy/ready handshaking supported

Call our HOTLINE ... eexatron

( 800)-538-8559 In California, Call (408)-737-7111

Exatron, inc.
181 Commercial Street Sunnyvale, California 94086 (408)-737-7111

Circle 20 on Reader Inquiry Card

JANUARY 1982 Digital Design 51

Product Index


Page Circle # #

To help you find the products you need, we·ve compiled a subject index of the ads and new products that appear in this issue. Organized by general product area, the li stings include the name of the manufacturer, the page on which the product appears and a

Computers and peripherals Omega Sales

IO 19

circle number for additional information on that product. Bold type indicates advertised products.

BC-223 desk-top computer
Braegen MPD
Desktop business system
Vector Graphic
Table top computer IMS Internati onal
Multiprocessor µ.C system OSM Computer
S-100 board Advanced Micro

45 8
59 IS8 64 IS9 64 179

132-column terminals Datamedia
Raster graphics board Se lanar
Video frame store Colorado Video
VT100 compatible terminal Colorgraphic Communications
Hard Copy

Page Circle # #
60 154

8/16-bit ROM simulator Inner Access

Page Circle # #
66 177

62 149

Multibus development control system
Distributed Computer Systems

57 22

66 173

Development system Zendex

2 6

66 172

Power Supplies, UPS, Line Conditioners


Digital Multitasking

65 170

Dot matrix printer Zenith Data Systems

59 160

Power conditioning Gould-Deltec

9 12

minicomputer Olivetti

66 180

µ.P compatible thermal printer


72 24

Power purification systems Controlled Power

C-3 70

Computers and peripherals Scherer's Mini-Computer Mart
Mass Memory
Winchester backup Kennedy

67 27 C-2

Computer 1/0
9000 series digitizer CalComp
Speech peripheral Telesensory Speech Systems

60 IS3

Silent UPS Clary Switching power supply General Instrument

50 IS 66 176

Streaming tape backup

PDP-11 parallel 1/0

Asynchronous line driver

Ampex, Memory Products Div.

43 II Computer Extension Systems

63 147 Bo-Sherrel

57 23

Winchester disk drive Four-Phase Systems
Dual-density tape drives Honeywell
45 ips tape transport Datum
Streaming tape subsystem Plessey Peripheral Systems
51/4 in. Winchester

58 ISS 58 IS7 59 13S 59 146

Add-In/Add-On Memory
Bulk semi memory Dataram Add-in graphics memory Peritek Maxiram storage system Imperial Technology
Controllers, Interfaces

7 3 49 7 71 28

Full duplex modern Fibronics
Computer site modem Racal-Vadic Data converter catalog ILC Data Device
Components, Hardware, Packaging, Switching

66 17S 64 16S 58 138

DMA Systems
Solid state disk subsystems Storage Technology Floppy disk drive

60 133 62 148

Disk/tape controllers Distributed Logic (Dilog)
PDP-11 VAX controller Spectra Logic

3 13 58 143

Busrouter Datafusion
DEC-compatible cabinets Everest Electronic Equipment

II 14 ...
56 26

Raytheon Data Systems Winchester series

64 166

Disk drive controller National Semiconductor

58 141

Pedestal bases and components

Leggett & Platt, EST Div.

65 17

Century Data Systems Disk subsystems Information Products Systems 8 in. fixed disk drives

64 130 65 142

Mini-floppy controller Micro Technology
Analog 110 controller Datastream Systems

58 140 60 134

Tabletop microchassis Configurable Micro Chassis
Fiber optic data sheet Canoga Data Systems

62 132
.. 59 131


65 128 Ethernet controllers

Semiconductors, ICs, µ.Ps


RS 232C stringy/floppy mass


60 ISi

storage Exatron

51 20

LSl-11 interface board Technical Magic

60 IS2

256KB MOS memory Professional Data Systems

51 21

19MB, 51/4 in. Winchester Computer memories
Video Display/Image Processing
Image processing systems Grinnell Systems

66 174 5 4

Low cost protocols I ntercon Research
Universal systems interface Shugart Assoc.
Sampling LSI controller Intel

62 139 62 ISO 62 137

256K DRAM board Rair Computer CMOS static RAM RCA
Forth application modules

64 164

64 181



Display terminal w/card security

Side door port

Timin Engineering

59 144


13 16 Kaufman Research

63 14S Other Products/Services


Video display terminal

Test Equipment,

Array processors


TeleVideo Systems

15 2S Instrumentation,

Sky Computers

65 18

Smart graphics terminal Modgraph
Digitizer GTCO
Image processing system Comtal

Development Systems
39 9 Advanced logic analysis

Accessories, Supplies
Printer ink rolls


58 IS6

Dolch Logic Instrument~
Load test instruments ACDC Electronics

C-4 2 59 126

Pore Ion

27 10

Employment Opportunities

58 129 Logic analyzer

µP professionals


59 136

United Technologies


52 Digital Design JANUARY 1982

' SHORT COURSES .~ATE for Electronics Industry Professionals ATE Software Tutorial -

These four informative short courses provide indepth study at introductory intermediate and

Definitions, Strategies, Management

advanced levels in selection, implementation, and management of test and measurement equipment - hardware and software.

Faculty: Damon C. Hart, President, Lexico Enterprises, Inc.
Roger L. Williams, General Manager, Applications Support Division, Lexico Enterprises, Inc.



Educating the attendee on all aspects of ATE software, th is course starts with introductory material for the beginner and builds up to advanced

March 1982 · San Jose, CA

material for software engineers already familiar with test programming and control software. Specifically, the instructors give useful definitions and

June 1982 ·Boston, MA

nomenclature; discuss the history of software ; describe software views of test strategies; thoroughly cover test languages ; review test system

October 1982 · Rosemont, IL

architecture including support, control and test application software ; carefully analyze all the stages required for test program development; analyze

November 1982 · Orlando, FL

the effectiveness of various software development tools ; talk about software procurement and predict future trends for ATE software.

ATE: How to Select It - Apply It - Manage It
Faculty: Arnold Greenspan, President, AMG Associates
Ralph P. Anderson, Product Une Manager, GenRad, Inc.
This course teaches the principles of automatic testing and their application to testing electronic assemblies. With emphasis on commercial ATE systems, the instructors provide an overview of all aspects of automatic testing , including hardware, system software, test application software and the tools used to develop, apply and manage a total ATE site or application. The course should prove of greatest value to engineers and managers who are newcomers to ATE, particularly those who are establishing and managing new applications. No prior experience in ATE is assumed, but attendees should have a basic understanding of electronics and the general capabilities of digital computers. The instructors encourage active participation by the attendees and will aid them in solving specific problems of interest to the class.

Advanced ATE Technology and Management
Faculty: Paul J. Giordano, Chief Executive Officer,
Giordano Associates, Inc. Philip C. Jackson, President, Giordano Associates, Inc.
Focusing primarily on commercial applications of automatic test systems to factory and depot testing , this 2-day course covers such topics as component test and the use of systems and subsystems for diagnostics and go/no-go screening. The course provides an overview of the state-of-the-art of ATE technology: description of ATE elements, ATE acquisition process, design for testability, testing requirements and test program set generation. It includes a review of ATE hardware/software, state-of-the-art ATE.configurations and future trends in ATE design . Finally, it gives members of the commercial sector an overview of military ATE : the criteria employed by major military programs to evaluate investments in ATE R&D funding , how these initiatives will affect available technology for commercial ATE and the impact of new military ATE concepts on aerospace manufacturers supplying equipment to that market.

Digital Board Testing
Faculty: Andrew Herman, Director, Test Engineering Institute, HHB, Inc.
Thomas W. Todd, President, Toddco General Engineering Associates

For more information, please return this coupon or call Registrar, ATE Short Courses, Morgan-Grampian Expositions Group, 2 Park Avenue, New York, NY 10016 (212) 340-9700


This course provides a thorough treatment of all aspects of digital testing. It is intended for people who want to broaden their understanding of digital testing, either as programmers or as supervisors of a test operation.

Please send me further information on the 1982 ATE Short Courses

Following an introduction to the basic concepts of Functional and InCircuit testing, the student is presented with guidelines for the conceptual-

Name __________________

ization and implementation of a test program. A sample circuit with its

associated test program and interface test adaptor design are used to Company _ _ _ _ _ _ _ _ _ _ _ _ _ __

demonstrate procedures.

Following the discussion of test program generation, the student is

Address ________________

presented with an overview of the hardware and software elements of a

test system, including simulators.

City________.State_ _ _ _,,_ip _ __


The course concludes with a discussion on testing digital printed circuit

boards containing LSI devices, including microprocessors. Throughout the presentation, heavy emphasis is placed on the "how to

Phone _ _ _ _ _ __

J 001 /82

· - - - - - - - - - - - - - - - - - - - - · do it" aspect of testing, especially in the area of test program generation


and Interface Test Adaptor design.

- -COMPAT Design- -

Q-Bus Controller for Winchesters Emulates DEC Devices and Supports Floppy Backup

Operating system software for widely used computers such as the DEC LSI11 represent a significant resource for the user. Well documented, thoroughly debugged, and fully supported, these operating systems, along with the device driver programs they invoke, are designed for the CPU manufacturers' peripherals. System houses offering mixed vendor DEC-based systems can provide improvements in cost and performance by mating products of independent device makers with DEC processors and operating systems.
Andromeda Systems, Inc . , a manufacturer specializing in LSI-11-based products, has done just this with its WDC 11, a new family of multifunction Q-bus controllers. The WDC 11 , contained on a single dual-width card, plugs directly into the Q-bus back-

plane, and through its bipolar microcontroller and ROM firmware can cause popular independent and floppy disks to emulate a variety of DEC devices.
The WDCl 1 actually serves three functions at once: with Winchester disks it emulates DEC's RK05 or RLOl/2 hard disks, and with floppy disks it emulates DEC's RX02 floppy. In addition, it provides an on-board ROM boot for system initialization.
The logical organization of the WDCl l is based on the 8X300 bipolar control chip, which provides the raw speed needed to handle high data rates inherent in Winchester devices. Data transfer to the host computer is via DMA, with 18 address bits implemented for direct addressing of 256kB of CPU memory space. Four additional

address bits are provided for the expected future DEC support of a 22 bit address field. Changeover to emulate one or another of the DEC devices is accomplished by merely plugging in
,. the appropriate ROM chip containing
the control firmware to drive the 8X300. The WDCl 1 represents one of the highest density packages for controllers on the market today, and the fitting of all of the required functions on a sing le dual width card is a significant packaging advance.
Depending on the device performing the emulation, a simple adapter or personality board may be required to accommodate differing connector pin outs and minor interface variations. These plug into the device proper and are entirely contained in its envelope. A variety of popular devices are currently







EH9602 EH9602 24 INCH EH960 191NCH
(714) 634-2200


. ·

EQUIPMENT 2100 E. Orangewood Ave.. Anaheim. CA 92806

56 Digital Design JANUARY 1982

Circle 26 on Reader Inquiry Card

Mark Detect Byte Timing Sector Timing

supported for the WDCl 1, including the Quantum 2000 and Shugart Assoc iates SAlOOO 811 Winchesters, the Computer Memories CM5000 and Seagate Technology ST506 5-1/4" Winchesters, the Shugart SA800, SA850, and Tandon TMl00-4 floppies or eq ui valents.
A significant feature of the WDCl l is its inherent ability to handle Winchester backup to a floppy, all in a sing le controller, thus eliminating one of the two controllers usually required.
Deli very of initial units of the WDCl 1 fami ly have begun . Prices are $2000 each for single quantities with OEM discounts offered . Andromeda Systems, Inc., 9000 Eton Avenue, Canoga Park, CA 91304 .
Circle 199

Winchester Read Data
Floppy Read Data

Data Separator/ Decoder

Sector Buffers






Bus lnterfac


Winchester Write Data Floppy Write Data
Read/Write Win/Floppy FM/MFM Sector Size
Write Gate
Disk Control Outputs Disk Status Inputs

Figure 1: Functional block diagram of Andromeda's Winchester-Floppy controller for LSI·11 Q-Bus. The WDC·11 controller contains all interface, formatting and signal recovery circuitry. Data transfer to the host computer is via OMA, with 18 address bits implemented for direct addressing of 256 Kb of CPU memory space. In addition, 4 more address bits are included for future DEC support of a 22 bit address field.

.... Announc,na .. ..
s ... .THE ~ ~ aa... .
..... l,nE OA,UEA .... . ... DLIAnT 'T'w' onE .. .

The bo-sherrel M-3 Asynchronous Line Driver provides full duplex data transmission over regular 4-wlre lines . It is end-to-end compatible with bo-sherrel's M-1 Short Haul Modem, but requires power from the attached terminal.

bo-sherrel co.
6101 Jarvis Avenue Newark, CA 94560 4, 5 + 792-0354

Quantity: 10 - 99 100-999 1000 - UP

Price: $83.00 $67.00 $51.00

Circle 23 on Reader Inquiry Card

DCS/86 {16 bit)


11 Development/ -::'""~r==~




· · ..


The DCS/86 is an industrial quality rack mountable Multibus* system based on the Intel 8086 16 bit microprocessor. A DCS/86 system includes dual 8" floppy disks with controller, DCS 86/16 CPU, 9-slot backplane, and heavy duty power supply. A 64K byte system with CPM/86** software is $6500.00.
MULTIBUS HARDWARE - DCS designs and manufactures a complete line of Multibus compatible modules which includes the DCS 86/16 that contains an 8086, 3 serial ports (two of which are capable of high-level protocols including HDLC and SDLC), vectored interrupt, counter/timer, RAM/PROM, 24 bits of parallel 1/0 and full multimaster capability.
SOFTWARE -The DCS/86 uti lizes CPM/86 **, a complete disk operating system with assembler, editor and utilities. 8080, 8085, Z80 to 8086 translation software is also available. High level languages include Basic, Pascal , Fortran, PL/I (Subset G) and Cobol .
DCS/80 - 8080 based system prices beg in at $3995.
* Multibus TM of Intel, ** CPM/86 TM of Digital Resea rch
Distributed Computer Systems 617 899-6619
223 Crescent Street, Waltham , Ma . 02154 Toll Free 1-800-225-4589

Circle 22 on Reader Inquiry Card JANUARY 1982 Digital Design 57


Doubles Storage Capacity In System IV/90 and IV/95

The 8291 is a fixed-disk Winchester drive

which features 138MB of formatted storage.

Since the IV/90 and IV/95 can both support

up to 4 disk drives, total storage capacity is

increased from 276MB to 552MB. Its Win-

chester technology offers the benefits of:

hermeticall y sealed head/disk assembly to

e liminate head crashes due to contamina-

tion: the heads fl y within 30 microinches of

the med ia resulting in greater recording den-

sities and faster access time: and. the media

is non-removable. insuring greater reliabil-

ity and reduced maintenance. Average

access time is 37. 12 ms. $22.000: $480/

month (42- month lease). Four-Phase Sys-

tems, 10700 N. DeAnza Blvd. Cupertino.

CA 95014.

Circle 155

Low Cost 11 x 11" Graphics Tablet
The DEMI-PAD 5 includes industrial quality , 200 points/sec digitizing. dual RS232 interface, l" lock height (digitize up to l" off the tablet surface), and the Z-80A µ.P which provides flexible output formatting. $735 : $551 in qty 100. GTCO Corp, 1055 First St , Rockville . MD 20850.
Circle 156


includes advanced dual bipolar µ.P architecture and switch selectable error correction in the controller's buffer or under standard DEC operating system control. Lost disk rotations and the need for sector interleaving are eliminated by use of single command conti guous sector data transfers up to 64K words . Access time is improved through overlapped seeks using separate registers for each logical disk. and separate sector counters allow rotational position sensing. Three versions of the SPECTRA 12 are available. $2900 in OEM qty. Spectra Logic Corp, 1227 lnnsbruck Dr, Sunnyvale, CA 94086. Circle 143
Low-Cost Version Of Vision One/ 1O
The Vision One/ 10-M6 is a compact. tabletop image processing system that can operate stand-alone or interfaced wi th a host. As a stand-alone system it provides digital image processing in real-time (l/30 sec) and has a wide array of processing features. Features include real-time zoom

instruments and data bus products. Nine separate product categories contain summary tables , background information. technical data, features , applications. block diagrams and outline drawings for each product in that category . Product categories
include A/D and DIA converters. sample/
hold and track/hold amplifiers, S/ R to D and D to S/R converters, synchro instruments. SEM and MIL-STD-1553 data bus products . ILC Data Device Corp, 105 Wilbur Place , Bohemia. NY 11716. Circle 138
For IBM's 64.5MB Winchester
The QUAD 3000 is the first si ngle-board DEC Q-bus controller for IBM 's 64.5MB drive . It uses the same architecture as National's HEX 3000 Unibus multi-device controller and incorporates their proprietary controller microengine. the XPU (Transfer Processing Unit). which implements a 4 bit wide microword architecture with bit slice components . With an input aggregate data rate of over 2MB/sec , and a 4 kB on-board high-speed buffer, the unit offers highly re liab le. flexible . guard-banded approach to 1/0 control. Under $3000. National Semiconductor Corp, 2900 Semiconductor Dr, Santa C lara. CA 95051.
Circle 141
DEC RX02 Hardware/Software Compatible

For use with the DPS 6 and Level 6 small

Utilizing a Tandon 96 tpi double-sided 5

computers, the bas ic tape subsystem con-

1/4" mini-floppy disk drive, Model Tl00-4.

sists of a magnetic tape controller and one

the RX02 doub le-density format has been

9-track primary magnetic tape drive: 3 tape

successfull y mapped onto a 5-1/4" double-

drives can be added to the su bsystem for a

sided double-density diskette. It is com-

total of 4 tape units. Each drive will operate

patible with LS I-11 computer systems.

in either 1600 bpi PE or 6250 bpi GCR .

MXV22M features include all interface.

Standard tape speed is 125 ips for a maxi-

bootstrap. and formatter electronics con-

mum throughput of 780.000 bytes/sec. It is and roam, pseudocolor processing , and con- tained on one dual-height card: operation on

supported by GCOS 6 MOD 400 system trast stretching. The operating system is standard device address and interrupt vector;

software which allows it to configure itself standard and the basic system includes 4 level device interrupt priority: Tandon

for the number of devices and type of record- memory control logic , pipeline processors , model Tl00-4 or Shugart SA460 96 tpi

ing format . The subsystem is also compatible with ANSI-standard GCR/PE tapes

power supplies . and the system computer. It can store up to four 512 x 512 images in

doub le-sided mini-floppy interface compatible ; 12 MHz crystal controlled clock: bit


created to run on IBM mainframes as well as memory and has optional features such as slice 290 1 µ.P Augmented Phase Locked

on Level 66 and Level 68 Honeywe ll largescale computers. First tape unit and control-

frame grabber, small -area processing. color hardcopy, and real-time arithmetic fu nc-

Loop; concurrent operation with 8" floppy disk systems: write precompensation ; IBM


ler is $52 ,000. Honeywell Inc, 200 Smith tions . The Vision One/10-M6 is $33 ,250. 3740 formatting; transparent firmware boot-

St. Waltham, MA 02154

Circle 157 Comtal Corp, 505 W. Woodbury Rd. strap : and power fail protection. The

Altadena, CA 91001.

Circle 129 MXV22M is fully compatible with the DEC


DY handler and will nm under the RT- 11.

SMD Controller With 2MB/Sec Transfer Rate
Thi s Unibus-compatible controller attaches

Includes Technical And Product Information

RSX- 11 , and RSX-llM operating systems. All operational and diagnostic software can


be copied over to the 5- 1/4" media on a


system that contains an 8" and a 5-1/4"

up to 4 SMD disk drives. and through switch Thi s 288 pp. app lications and product cata- drive. $1260. OEM qty 50 is $945. Micro

se lection. up to 16 different drive types can log describes company's standard line of Technology Inc, 2192 Martin. Suite 230.

be confi gured on each of the 4 disk ports . It data converters. hybrid modules. synchro Irvine , CA 927 15 .

Circle 140

58 Digital Design JANUARY 1982


Tests Variety Of DC Power Sources

As a basic load , the EL300 is a low cost

solution for loading power supplies under

test or for burn-in. Used with the EL30l

Instrument Module it is a precision, pro-

grammable test system. The EL300 dynam-

ic load module, with internal fan, can dissi-

pate 300W continuously when operated

from an AC Line. DC power sources from

4.5 to 60 VDC, up to 60A, can be tested for

proper operation or burned in. As a portable

test instrument it will operate with no line

power and dissipate up to 250W @ 50%

duty cycle (l50W continuously). The

EL30l instrument control module expands

operational capabilities. It can monitor and

program up to 6 loads. provides for testing

DC level s as low as l. 8 VDC ( l.5 VDC

derated) and for dynamic loading in two

modes. It also facilitates programming from

a variety of external voltage waveforms.

EL300 Load is $495: El30l Control

Module , $550: OEM discount avail. ACDC

Electronics, 401 Jones Rd , Oceanside. CA


Circle 126


Contains Hundreds Of Definitions Not Previously Published

Included on the diskette are data structures,

software development aids , string manipu-

lators , an expanded 32-bit vocabulary, a

screen calculator, a typing practice pro-

gram, and a menu generation/selection pro-

gram. In addition , the diskette provides

examples of recursion. < BUILDS ... DOES>

usage, output number formatting , assembler

definit ions, and conversational programs.

100 screens of software and 100 screens of

instructional documentation are supplied on

the diskette . $75 . Timin Engineering Co,

9575 Genesee Ave, Suite E-2. San Diego.




Features Embedded Formatter
In addition to the host drive. the formatter can also service 3 additional. daisy-chained transports. A proprietary automatic restart function retensions the tape and puts the drive back on line after power interruption .

The drive 's electronic design incorporates

all read. write and control logic on one

board. increasing reliability and enhancing

maintainability. Powered by the 0451. this

embedded formatter performs 80-90% of

standard controller functions. On 10-1/2"

reels. the 0451 F powers 1/2" tape at 25.

37 .5 and 45 ips. The drive encompasses

either NRZI. PE or dual-density formats.

IBM/ ANSI compatible for 9-track units.

with density selection available from the

front panel. The 0451 F includes full I yr.

warranty. $6300. qty discounts avail.

Datum Inc, 1363 S. State College Blvd.

Anaheim. CA 92806.

Circle 135


correct up to 5 erroneous bits in every 256 bytes transferred from disk to processor. This eliminates errors due to disk contamination. surface defects. etc. A 630 kB floppy disk. incorporated in the same module as the Winchester. is identical to that used in other Vector systems so programs and data can easi ly be transferred between the 3032 and other µCs. The 3032 is $12.795. Vector Graphic lnc,500 N. Ventu Park Rd. Thousand Oaks. CA 91320.
Circle 158


Flexible Time And Data Recording Capability

Model Kl02-D is a lower-priced version of

the KlOl-D that can be upgraded as needed.

It has 32 data inputs and 8 clock inputs, and

includes an internal clock which can sample

data inputs as fast as 100 MHz. The Kl02-D

offers versatile clocking modes, selective

software tracing (recording), flexible signal

conditioning , 4 input modes, 3 display

formats, 3 standard interface features , an

integrated digital voltmeter and a frequency

counter. $16,900. Gould Inc, Biomation

Operation, 4600 Old Ironsides Dr, Santa

Clara, CA 95050.

Circle 136


Prints 150 CPS At Up To 300 LPM

The Z-25 interfaces with standard µ.C

systems using serial RS-232C or 20 mA

current loop. Designed with 3 modules -

print. paper handling and electronics -

downtime is lessened since modules are

simply swapped for maintenance. Features

include quiet operation. an inked nylon

cartridge ribbon for easy replacement. a

9x9 dot matrix. 95 ASCII characters. U/L

case. and 33 graphics characters. Character

width is selectable from 10. 12. 13.2or 16.5

cpi on paper from 3.5" to 17.8" in width.

Zenith Data Systems, 1000 Milwaukee

Ave. Glenview. IL60025.


Offers Complete Data Security
Model CSY-306 provides complete data security. error rates 10.000 times lower than

New Level Of Cost!Performance
The 3032 µ.C system has 32MB Winchester disk storage and a Z80b. 6 MHz µ.P that

STREAMING TAPE SUBSYSTEM Fast Backup For Q-Bus Disk Systems

comparable hard-wire connected modems. increases system performance . The 8" The PM-CSVl IA fits a standard 8" floppy

and complete electrical isolation. Inter- Winchester disk enables full use of the drive enclosure and provides backup for a

computer data transfer over distances up to I maximum size files allowed by Vector's 28MB 811 Winchester-type drive in the

km or more is possible . Available with CP/M 2 operating system. The DualMode SYST-23VTJ configuration. It stores 8000

standard CCITT V. 35. EIA RS449/422 or disk controller provides automatic error bpi. recording 90 ips on 4 tracks. An RK05

RS449/423 electrical interfaces. the CSY- detection and correction to automatically disk can be backed up or restored in 30

306 operates at selectable data rates from 56


Kbps to 2 .688 Mbps. Other data rates from

2.4 Kbps to 4.0 Mbps are possible using an

seconds. Software to support streaming. the Cartridge Image Backup (CIB) is non-tile structured similar to DECs RSX-1 IM

external clock or an alternate internal

PRES RV utility . The subsystem consists of

crystal. This full duplex modem provides

a dual-wide Q-bus controller. 1/4" tape

handshaking signal options including RTS.

drive. all related cables and the CIB utility.

CTS. DTR. DCD. and DSR . and has a

Rackmountable enclosure is also available .

manually selectable remote loopback

A 300' tape cartridge can backup 4 RK05

feature. To insure data loop integrity .

disk units . 2 RLOI units. an RL02 or an

optical signals in both directions are con-

RK06 for approximately $20.00. The PM-

tinuously monitored. $1800. qty discounts

CSV 11 A is $3600 . OEM discounts avail.

avail. Canoga Data Systems, 21218

Plessey Peripheral Systems, 1691

Vanowen St. Canoga Park . CA 91303.

Browning. Irvine. CA 92714.

Circle 131

Circle 146

JANUARY 1982 Digital Design 59


Broadens Voice Output Product Line

The SP1020 is a stand-alone electronic

voice respon se unit wh ich interfaces to

a lmost any mainframe. mini or microcom-

puter system via an RS232C serial port. The

enclosure contains the speech synthesizing

unit. vocabulary memory . amplifier. power

supply. interface electronics and front panel

controls. Messages in virtually any lan-

guage using male or fem ale voices are stored

on sem iconductor memory devices for easy

random access of words or whole phrases.

Up to 200 seconds of speech may be stored.

Vocabularies may be obtained to meet

specific application requirements and direct

access to e ncoded speech data over the tele-

phone network is provided. The SP1020

Speech Peripheral is $2500: Vocabulary

Generation Services from $50/custom word

to $1.60/word for Numerics Plus 62 word

standard vocabulary. A SPEECH 1000

Synthesizer Board is $1200. Telesensory

Speech Systems, 3408 Hillview Ave. Palo

Alto. CA 94304.

Circle 153

Couples Analog Conversion Equipment ToQ-Bus Systems
The design eliminates congested analog wiring to the controller board and allows the analog conversion system to occupy as much space as required for a given applicati on. The OS 100 is capable of continuous

LSl-11 Q-Bus And Unibus Compatible
The two products provide Ethernet controller functions at 10 megabits/sec for DEC systems. Either contro ller. with a 3CIOO Ethernet transceiver. provides complete support for layers one (phys ical) and two (data link) of the International Standards Organization Open System Interconnection Reference Model so that any DEC computer

wi ll be compatible with any other Ethernet-

based system. A DEC computer running the

UNIX operating system. with enhanced

UNET. new controller. and transceiver. can

become a complete Ethernet loca l computer

network station. This system provides

communication through all 7 levels of the

ISO model. with UNET providing powerful

file transfer. virtual terminal. electronic

mail transfer and process-to-process com-

munication capabilities via the 5 upper

layers. The 3C200 Q-bus controller is

$2500: the 3C300 Unibus controller is

$3000: qty discounts avail. 3COM Corp,

1390 Shorebird Way. Mountain View. CA


Circle 151


age data access time is 40 ms. data transfer r~te is 5 MHz . It mounts directly into

housings designed for mini-tloppy disks . A

simpl e electronic interface gives OEM

designers performance upgrade for mini-

tloppy-based systems as well as for 5-1/4"

disk systems that only feature fixed media .

Imbedded-servo technology improves track

following and access time performance.

complemented by an improved linear motor

positioning system. In OEM qty the

MICRO-MAGNUM 5/5 is $1275. OMA

Systems, 325 Chapala St. Santa Barbara.

CA 93101 .

Circle 133

Saves Backplane Space
The 8S half wide board is fully compatible with the LSI- I I Q-bus. contains 8 standard. full-duplex serial ports and features the use of lead less chip carriers. Selection of one of the 8 ports as the console is possible and each port can be independently configured for RS-232C . RS-422. or RS-423 communication protocol. Jumper plugs allow independent selection of word length . number of stop bits. parity checking. parity sense. and baud rates from 75 to 76.8K baud. An optional 153.6K baud rate is also offered. Addresses and vectors are jumper plug se lectable over the full range and can be placed anywhere within the entire 1/0

space. Completely DLV 11-J plug compat-

ible. the 8S has 4 selectable bits for the

vector which permits up to 16 boards to be

used in a backplane. $650 (qty 100) .

Technical Magic, 17742A Mitchell Ave.

Irvine. CA 92714.

Circle 152

With Fixed/Removable File Storage


throughput exceeding 90.000 16-bit

The MICRO-MAGNUM 5/5 disk drive comprises two 5-1/4" disks . One is an internal. non-removable component of the

DG-Compatible Color And B&W Terminals

samples/sec to a 125 ips PE magnetic tape disk drive. and the other disk is a removable. The terminals offer editing features not

drive. Throughput to Q-bus memory is at

availab le with DG displays such as insert/

250.000 16-bit samp l e,~/sec. The contro ller

delete a line, erase end of screen, clear

board occupies one quad slot of a Q-bus

highlighted areas, lock/unlock keyboard ,

backplane and provides control for up to 256

foreground/background mode and secure

AID input channels and 256 DI A output

field. They also offer bidirectional scrolling.

c hannels . The controller uses a Z8002 16-bit

split screen/regional scrolling. and a special

µ,P to control its hardware functions with up

set-up mode that allows operating param-

to 4k words of program memory avai lable.

eters to be changed from the keyboard.

On-board diagnostic software aids in

Characters can be displayed in a variety of

checking the controller functions and integ-

sizes and pitches: and, business graphic

rity of the data paths. The OS 100 1/0 con-

symbols are standard with the 128 ASCII

troller board with software and integration to portable data cartridge. The unit provides character set . The monochromatic Excel 70


user· s choice of analog conversion front-end mass storage. I/0 . and back-up file gener- series starts at $1395: the 8-color Colorscan

subsystem is $3500 . Datastream Systems, ation. Storage capacity of each disk is 5 MB 70 is $3195: qty discounts avail. Datamedia

13516 Ring Rd . Poway . CA 92064.

of formatted data. for a system total of 10 Corp, 7401 Central Hwy , Pennsauken. NJ

Circle 134 MB (13.5 MB of unformatted data). Aver- 08109.

Circle 154

60 Digital Design JANUARY 1982

Broaden your testing knowledge and update your testing skills



Automated Testing for Electronics Manufacturing

JUNE 14-17, 1982 Hynes Auditorium


Boston, MA

Field Testing

Analog Board Test

The full scale technical conference offers a 31h-day program of workshops, technical papers , and an operating equipment exhibit. In addition you can select from a concurrent program of in-depth courses available in a spec ial course/conference plan.
Specific information and application-oriented guidance from the faculty, augmented by equipment demonstrations at the large- scale exhibit of test and measurement equipment , will help you make the right deci sions on investments and implementation.
For more information, send the coupon to: ATE Seminar/Exhibit Registrar Morgan-Grampian Expositions Group 2 Park Avenue New York, NY 10016 (212) 340-9700

· Handlers · IC testers · Field, depot and maintenance testers ·Microprocessor troubleshooting and development tools · Automatic measuring instruments meters, generators, analyzers, scopes, counters · Memory testers · Calibration instruments · System testers · In-circuit testers · Bare board testers · PCB assembly testers ·Bum-in/Temperature cycling systems · Cable/wiring/harness testers · Test services · Interfaces
In conjunction with the ATE Seminar/Exhibit, other seminars and courses of interest to the test industry professional include:
ATE Software- Definitions, Strategies, Management

Logic Analy~is Techniques Loaded Board Functional and Jn-Circuit Testing Phase Measurement LSI Component Test Microprocessor Bus Fault
Spectrum Analysis Analog Diagnostics Bum-In/Temperature Cycling Instrument Calibration Test Requirements Analysis Simulation Signature Analysis Systems Support Management ATE Acquisition Impedance Measurements Economics of Loaded Board Test Bare Board Testing LSI Board Test Timer/Counter Measurement
Digital Diagnostics

Wavefom1 Analysis Bubble Memory Testing Implementing the IEEE 488 Bus Interfacing Devices Automatic Test Generation ATE Management Testability ATE Systems Calibration Test Programming Electro-Optic Testing Using IEEE Bu~ Instruments

0 ATE Seminar/Exhibit. June 14-17 . 1982 0 ATE Short Courses . June 15-17. 1982

Advanced ATE Technology and Management
Automatic Test Equipment:

0 Quali1y and Engineering Factors in Fabricating Prin1ed
Circuil Boards. June 14. 1982

How To Select It-Apply It -Manage It

NAME _ _ _ _ _ _ _ _ TITLE _

Introduction to Digital Testing

COMPANY _ _ _ _ __

Quality an.d Engineering Factors in Fabricating


Printed Circuit Boards


ZIP_ _ __

Sponsored by

.._________________________. _- - - - - --- ---- - --- - rnD@CSlS[?@QUDCS~ u®~ts co-sponsored by Circuits Manufacturing, Digital Design and Design Engineering

Rewrn coupon 10 ATE Seminar/Exhibit Registrar, Morgan-Grampi an Exposi1ions Group
- 2 Park Avenue. New York. NY 10016 <2121340-9700 DD 1/82

Flexible II 0 Interface For LSl-11 Series
The l 664ATTL card has 8 registers which can be jumper programmed to operate as input ports. output ports. or mixed 1/0 ports. When programmed as an input. the associated port accepts data from digital devices

such as voltmeters. bit switches. and key-

boards . As an output. the associated port

drives devices such as printers and CRT's.

Another jumper programmable feature

permits all output latches to be set. or reset.

upon power up initialization. Latching

registers provide noise immunity against

logic level changes. $350: qty discounts

avail. ADAC Corp, 70 Tower Office Park.

Woburn. MA 01801.

Circle 127

commands provide graphics capabilities. Maximum input data rate is 9600 baud. average printing rate is 752 graphics columns/sec with speed enhancement features to skip over blank areas. A graphics board enhancement for the YTIOO is also availab le . With the LA 120 and the SG 120R. typical graphics images on the YTIOO can be printed in 17 seconds with expanded size images in about one minute . A higher level of resolution than previously available in raster graphics is provided. The SG120R board is $600 . Selanar Corp, 437-A Aldo Ave. Santa Clara. CA 95050. Circle 149
For DEC VAX, PDP-11 And CP/M Micros
lntercon 100 Intelligent Interface offers a sync communication link via dedicated or dial up lines at data rates up to 9600 bps . It is a µ.P-based stand-alone device with self contained protocols and async/sync data conversion. Software handlers are available for use with VMS . RSX-1 IM orCP/M. The unit allows mini/microcomputers to be transparent to the user and allows disk-to-

of standard host adapters. The SA 1400

series of controllers with a SAS! interface

begin at $565 in OEM qty. Shugart Assoc,

475 Oakmead Pkwy. Sunnyvale. CA


Circle 150


For 64K Dynamic RAMs

The 8203. an LSI peripheral controller chip.

controls and automaticall y refreshes arrays

of 64K dynamic RAM s in µ.C systems and

on memory expansion boards. It performs

multiplexing of row/column memory ad-

dresses: generation of strobes used by

RAMs to latch their addresses internally:

initiation and control of memory refresh

cycles: arbitration between simultaneous

requests for memory access (R/W) and re-

fresh: and. acknowledgement to the system

CPU when memory access cycles actually

begin. The 8203 has on-chip array drivers

and damping resistors in series with the

address multiplexer outputs. further reduc-

ing system chip count. It controls up to 64.

64K RAMs totalling 256 kB of capacity. It

can a lso be strapped to operate with 16K

dynamic RAMs . $27 . 15 (qty 100). Intel

Corp, 2625 Walsh Ave. Santa Clara. CA


Circle 137

Holds 6 Multibus Cards And Two 5-114" Disks Or Bubble Memory

Performance And Reliability Improvements

/ 1,/tl/"1# ;/)(/
.....~ ,__

From 4 to 9 slot backplanes compatible with both the Multibus system bus and the rEEE P796 standard may be selected. The chassis contain switching power supplies from 60 to 200W. Configurations may include up to

Both models are fully hardware and soft-

two 5- 1/4" floppy or Winchester disk drives

,.. ware compatible for virtual storage paging disk transfer of files between the remote host and up to 4 bubble memory modules. All

applications on IBM 370. 303X. 4300. and users ' local computer. Capacity for up include forced air cooling through the card

308X and equivalent processors. Both to 4 PROM resident protocols are switch cage. magnetic circ uit breakers to prevent

employ 16-kilobit. MOS RAM integrated selectable . Presently available are: CDC board failures from AC power supply

circuits for data storage. The 4305-Model 3 200UT. IBM 3780 and 2780. lntercon 100 arcing. power supplies allowing input

provides 11 .25 or 22.5 MB of semicon- with I protocol is $3995 . additional proto- vo ltage variations from 90-132 or 180-264

ductor storage with a single controller. cols are $1000. lntercon Research Corp,

Access speed is 0.6 ms with initial data 2603 Artie St. SW. Suite 14. Huntsville. AL

transfer rates of 1.0 and 1.5 MB/sec. From 35805.


$84. 000 to $141. 160. The 4305-Model 6

provides 11 .25. 22.5. 33 or45 MB of semi- UNIVERSAL SYSTEMS

conductor storage and either one or two INTERFACE

control units . Data access speed is 0.3 ms. Model 6 offers more versatility than Model 3 with better data availability. higher

Upgrade, Mix And Interchange Memory Peripherals


transfer rates. and dual port and four- Without affecting the CPU operating system

channel access. Transfer rates are 1.0 and or applications program. SAS! allows

1.5 MB/sec. optional performance specifi- floppy. rigid . streaming tape canridge and

cations include 3 MB/sec data rate in two- future generation optical disk drives to use a

byte wide or data streaming modes . From standard system interface . On the drive

$140.380 to $489.940. Storage Technology level. it eliminates the need for developing VAC. and 16 ms of full power avai lability

Corp, 2270 S. 88th St. Louisville. CO new controllers. host adapters and software after total power failures. Model CMC-6FF-


Circle 148 drivers each time a new memory device is 160 with a 6 slot backplane and a rear panel

available. Standardization at the systems with spate for up to 6 1/0 connectors. a


level allows the development of a standard I60W switching power supply and dual

Graphics Output From DEC LA120 Terminal

set of custom LSI chips. resulting in significant cost savings and performance improvements. At the host CPU level. SAS!

minifloppy 440 kB capacity drives compatible with Intel iSBX-218 floppy disk controllers. is $2800: chassis without drives


The SG l 20R board does not affect the 1/0 permits a variety of memory subsystems is $2100 . OEM discounts avail. Config-

circuitry of the LA 120 and the printer retains (controllers and memory devices) to attach urable Micro Chassis, 34 Church Ave.

all of its original capabilities while new to different host CPU buses through the use Northport. NY 11768.

Circle 132

62 Digital Design JANUARY 1982

Hardware And Software Compatible With DEC DR11C
The PIO 11 requires one Quad SPC slot in the Unibus. It has been enhanced over the DR 11 C by an option that allows the user to select standard TTL output signals. or high current open collector output signals. On-


------ board DIP switches allow easy selection of
address and vector locations . Complete hardware and software compatibility to all operati ng and diagnostic systems is maintai ned. $395. OEM discounts avail. Computer Extension Systems Inc, 17511 El Camino Real. Houston. TX 77058 .
Circle 147
Enables Single Terminal To Talk To Two Computers
When a CPU has to perform protocol conversion. terminal emulation and polling operations. it ties up machine cycles and memory space. These tasks can be performed externally by the Side Door Line Interface Module (LIM ). so the computer is freed to do other tasks . The Side Door LIM eliminates any requirement for adding wires. sw itches and enables the user to c hoose the computer he wants to talk to . No modifications of the host or local CPU soft-
The unit can talk with

virtually any local computer which has an

async port. Designated the DLA-100-SD. it

is used in conjunction with the Kaufman

Research True Port Concentrator. Both a

polled concentrator and an emulator. these

products support multidrop polling in multi-

ple clusters of 8 terminals each. Any of a

large number of ASCII devices can be sup-

ported. inc luding special and non-standard

terminals. True Port Concentrators are

$4890 with one LIM with Side Door. to

$10 .595 for 8 LIMs and 8 Side Doors. For

existing True Port Concentrators. the Side

Door LIM is $815 . Kaufman Research

Manufacturing Inc, 2260 Mora Dr. Moun-

tain View. CA 94040 .

Circle 145

Hamilton Standard , a world leader in sophisticated control systems and automatic test equi pm ent , is currently seeking microprocessor professionals in the following disciplines to staff several of our exciting programs .
Among our programs are microprocessor based fuel controls for diesel and gas turbine engines, environmental control systems for aerospace applications , aircraft flight control systems , and special purpose automatic test equipment for aerospace and industrial systems . Our programs involve use of state-of-the-art and advanced circuitry such as commercially available and custom microprocessors to accomplish control and direction of a system. Employment at Hamilton Standard will provide you with technical challenges and an opportunity to be involved in achieving major breakthroughs in technology. We offer salaries fully commensurate with education and techn ical background , an excellent benefit package , and a challenging and rewarding future . To t:Je considered for these positions, please send your resume in confidence to :
Michael C. Bowen Senior Professional Recruiter Hamilton Standard Division United Technologies Windsor Locks, CT 06096
or call collect: (203) 623-1621, ext. 2372
JANUARY 1982 Digital Design 63



Replaces 7 Bell Models

190 And 380 MB Of Fixed Storage

Single-Board Memory Option
By using high-density 64K RAMs. a full 256kB of high-speed MOS memory is provided on a si ngle board. Users of the Black Box range may incorporate 2 of the 10 x 4 1/2" boards into a si ngle microcomputer to provide a full 1/2 MB of RAM storage.

The VA 3 15 series direct connect. 300 bps

fu ll duplex modem. can automatically or

manually ori ginate or answer calls. and

handles all applications for full duplex 0-300

bps data transmission over the dial-up net-

work. It replaces Bell type modems: 103A.

103E. 1031. l 13A. l 13C and I 13D. It is

compatible with Model VA8 I I si ngleline/

multiline automatic calling unit. making it

possible fur a si ngle RS366 or RS232 com-

puter port to provide automatic diali ng for

up to 60 VA3 15 modems . The YA3 15 con-

tains ex tensive diagnostic and test features.

The interface display coupled with local

(analog) and digital loopback allows easy

isolation of network problems. $375. OEM

discounts avail. Racal-Vadic, 222 Caspian

Dr. Sunnyvale. CA 94086.

Circle 165


The Advanced Marksman Series (AMS) initial offerings feature 190 and 380 MB of fixed storage in a drive that has the same form/fit as Century's 20. 40. 80 and 160 MB units. A linear motor positioner provides a fast positioning time for 14" Winchesters . Features include a spin motor brake. a carriage lock for use during shipment and a ve ntilated spindle to provide uniform cooling of the disks . This spindle eliminates the cond ition in which disks in multi-platter.
·· ....

Includes Winchester Plus Minifloppies

The 5000 SX table top computer has an

integral 5.5MB Winchester drive and can

also contain 2 double-sided . double-track-

Access is via a powerful memory manage- density floppies . The Winchester subsystem sealed drives expand at different rates and

ment unit. standard with Black Box sys- is comparable to large mainframe hard disk affect data reliability . Century Data Sys-

tems. which extends the normal addressing systems in terms of speed. A 20K program tems, 1270 N. Kraemer Blvd. Anaheim.

range from 64K to 512K. and is fully sup- can be loaded in less than a second . about 10 CA 92806 .

Circle 130

ported by an advanced multi-user MP/M to 12 ti mes faster than with a floppy . Operat-

operating system. $2500/256kB. the Black Box 3/30 is $7500: qty discounts avail. Rair Computer Corp, 4101 Burton Dr. Santa

MULTIPROCESSOR µC SYSTEM Expandable From 1 To 64 Users

Clara. CA 95050.

Circle 164

With ZEUS TI each user has a dedicated


single board computer module with a Z80A CPU . 64K RAM. and dual serial I/O . A

Redesigned For Higher Speed And Performance
Faster versions of the MWS5114 4K static RAM . the MWS5114-3. -2 and - I have access times of 200. 250 and 300 ns. Organi zed as 1024 words by 4 bits. the RAM s are fabricated in ion-implanted silicon-gate CMOS technology for low power consumption. They retain data at voltages as low as 2V over the 0 to 70°C operating range. This allows them to be

ing systems are CPM . MPM. Single and


and COBOL are availab le. IMS Inter-

national, 2800 Lockheed Way. Carson

City. NY 89701.

Circle 159

similar two board module serves as a master supervisi ng all user requests for shared storage and peripherals. The master processor module also includes on board floppy controller. peripheral interfaces. DMA. and real-time clock with battery backup. The

applied in battery backup systems in which system power is provided by a standby battery when normal electrical power either fails or is intentional ly shut down. All inputs

Supports PTS/1220 Distributed Processing System

and outputs to the devices are TfL com- Inte nded for the DDP user with limited stor-

patible. giving users the benefits of low- age requirements. the PTS/1220 offers up to

4 . IMB on 4 daisy-chained drives. The


-"oo -vss

direct-access . data storage devices use re-


movable 8" diskettes . The processor's drive

uses a two-sided. double-density . flexible

diskette with a recording density of 6.816

bpi and a formatted capacity of I .025MB.

Track-to-track access time is 3 ms. Model

3831 Field Upgrade Diskette System with controller. adapter. expansion chassis and



first l.025MB diskette drive. cables and

Block diagram ·for MWS5114

software is $4100; Models 3832 and 3834,

power CMOS and the high-speed of TfL in field or factory installed drives are $1650; MUSE (Multi-User System Executive)


mixed technology systems . From $6 . to Model 3833 Diskette Expansion Chassis and operating system is CP/M compatible and

$7.40 ( 100 qty): higher volume discounts l .025MB drive is $2850. Raytheon Data provides a true multiuser environment. OSM

ava il. RCA, Solid State Div . Box 3200. Systems, 1415 Boston-Providence Tpke. Computer Corp, 2364 Walsh Ave. Santa

Somerville. NJ 08876.

Circle 181 Norwood. MA 02062.

Circle 166 C lara. CA 9505 1.

Circle 179

64 Digital Design JANUARY 1982

Include Controllers To Monitor 110 Channels
Supporti ng PDP 11 and VAX 11/780. P-E 3200 series and DG Nova and Eclipse series computers. these subsystems are fully software transparent to the mainframe operating systems. True logical unit emulation is achieved through the controller design. The controllers are intelligent peripheral processors which monitor I/O channel activity to max imi ze system throughput. These systems support multiple sector buffering and extended data error recovery algorithms. Features include multi-drive support. overlap seek. burst error correction. and multidrive radial interface. A 160 MB Winchester disk subsystem for the PDP 11-34 is under $12 .000. Information Products Systems, 6567 Rooki n. Houston . TX 77074 .
Circle 142
Complete System On A Single Board
The SUPER/NET board consists of 64K bank select dynamic RAM. Z80A CPU. 27 16 (2K) monitor EPROM. 5v.i'' and 8" floppy disk controller. two serial and two parallel interface ports and Z80A CTC for

pedestal bases and components for terminal stands

The EST Company offers a complete line of pedestal bases and components for stationary or movable stands for terminals or printers.
We offer seven styles of 4-leg pedestal bases in sizes from 19" to 34" spreads, and three styles of 5-leg pedestal bases in sizes ranging from 22" to 28" spreads.
Our line of uprights and top plates can match your needs for those stands.
Let us quote your custom casting needs or work with you on your stand unit design.



Circle 17 on Reader Inquiry Card

real-time interrupts . Full DMA operation is

supported. SUPER/NET meets full rEEE-

696 specifications and operates under both

CP/M and MP/M software. As a single user system it allows addition of mor~ user-

defined options at lower cost. Its bus master

ab ility suits it for use in a multi-user en-

".ironment. $1125 . Advanced Micro Digital

Corp, 720 I Garden Grove Blvd. Suite# E.

Garden Grove. CA 9264 1.

Circle 170


49. 7 And 82.9 MB Unformatted Capacity

The Scorpio family includes Model 48 with

49 .7 MB and Model 80 with 82.9 MB of

unformatted capacity and 20.160 bytes/

track over 823 cylinders . Average access

ti me is 30 ms with a data transfer rate o f l .2

MB and an average latencv of 8.3 ms with a

linear voice coil-actuator" in a closed-loop

servo system. All critical recording com-

ponents are enclosed in an environmentally

sealed module . Integrity is furth er insured

through the use of head landing zones .

module shock mounting. and self-actuating head-carriage and disk--spindle locks. Th~

drives initially offer the industry-standard

SMD interface. Ampex, Memory Products

Div. 200 N. Nash St. El Segundo. CA


- Circle 128

LS/-11· Q-Bus · ARRAYPROCESSOR Full Floating Point, Under $6K
Do you do ... FFTs. digital filtering, vector math, matrix manipulations or other signal processing algorithms 7
We do too! Do you do them FAST on an 11/03, 11/2, or an 11/23 7
We do ! ... and so can you.
In fact, the SKYMNK Micro Number Kruncher is already designed into: Seismic Modeling Systems Speech and Image Processing Systems Medical Electronics Systems Simulation Systems Laser Systems Analysis . .. and more
If a microcomputer is in your system design. ~ ." Maybe we should be in your system!
SKYMNK - THE Array Processor for microcomputers.
IMMEDIATE DELIVERY Call or write for more information.
· tradename of Digital Equipment Corporation
SKY COMPUTERS, INC., P.O. Box 8008, Lowell, MA. 01853 (617) 454-6200
Circle 18 on Reader Inquiry Card
JANUARY 1982 Digital Design 65

Provides Linear Regulation
The OSP-50 provides the load regulation normally associated in a linear power supply with the size and weight advantages of a switching power supply. It features a userselectable 120/240 YAC input and 3 fully regulated outputs. Standard DC outputs

16-Bit Mini with Multiuser Capability
Features of the S6000 include: expandability to 24 external peripherals. including terminal displays. printers. tape drives . etc: and. the ability to expand to I MB of memory and disk storage to a maximum of360MB. It supports BASIC. PASCAL. LISP and Assembler programming languages plus a comprehensive text editing software package. It also features optional data communication capability. A variety of system configurations are available. All are supported by OMOS which supports several users on the system at the same time. all running the same or different programs. Olivetti Corp, 155 White Plains Rd. Tarrytown. NY 10591.
Circle 180

4 user assignable 1/0 ports: no S- 100 memory space is needed to hold ROM data. The board is provided with 4kB of RAM expandable to 16kB. $495 . Inner Access Corp, 517-K Marine View. Belmont. CA 94002.
Provides 2 Forms Of Image Modification
Model 274D Digital Video Frame Store provides two forms of video image modification with simple front panel controls. The basic memory captures a high quality 512 x 512 e lement image with 256 shades of grey . Front panel switches allow any or all of the grey scale components to be selected or deleted for posterization effects. and

include + 5Y@8A. + 12Y(cil 1A and - 12Y(cil 1A: or. +5V@8A. + 15Y(cil 1A and - 15Y@ 1A. The size of the supply is 2-1/2"x8"x5.65". Other standard features include free-standing PC board construction. soft start input. full overcurrent protection. input EM! filtering. + SY overvoltage protection. 65 % typical efficiency and full brown-out protection. Primary application areas include VDTs. monitors. small computers and floppy disk systems as well as process control equipment. General Instrument Corp, Computer Products Div . 1401 Lomaland Dr. El Paso . TX 79935.
Circle 176
Operates Over A Single Fiber
With the FM-801 modem. networking is simplified. For distances up to 3 km . only one-channel. PCS fiberoptic cable is needed . Thus. cable costs are reduced by 40% and termination costs are halved. The modem is ideal for point-to-point applications and multi -drop use (using Fibronics TS-10 optical splitters). Sync data rates to 19 .2K bps and async transmission to 4800 bps are standard. Automatic self-test features as well as remote loopback and local

19 MB, 5-1/4"WINCHESTER 3 Versions With 5 MB Formatted Data! Platter
The CM 5000 features Winchester technology. identical mounting to standard 5-1/4'' floppy drives. and no-hysteresis positioning system. Other key features
include: internal µ.P: step-pulse buffering: high output and high resolution heads: offtrack positioning capability: all electron ics and motors located outside clean area: and, optional transfer rate for 8" Winchester compatibility. Computer Memories Inc, 9233 Eton Ave. Chatsworth. CA 91311.
Circle 174

resolution of the frozen image is variable in steps down to 16 x 16 blocks. The 274D accepts standard video signals for freezing and processing. and may also be interfaced to conventional computers for more elaborate image alteration. $9100. Colorado Video Inc, Box 928, Boulder, CO 80306.
Circle 173
ColorTerminal That Operates With Existing Monochrome Software
The MYI-7. a 13" preconverged color terminal. features vertical and horizontal scroll. 4 independently addressable and scrollable screens. 2 pages of screen memory and 1280 user programmable symbo ls. The terminal is RS232C/RS422 or Current Loop compatible. It displays 80 characters by 24 columns in addition to a status line: and. memory may be configured for 80 x 56. 140 x 32 or 160 x 28 to allow for non-destructive horizontal and vertical scroll . The MYl-7 also has powerful local

loopback capabilities verify link operation and offer complete and continuous fault monitoring control. All RS-232C handshaking features are built in. Fibronics, 655 Concord St. Framingham. MA 0 1701.
Circle 175


Speeds Software Design In S-100

The S-100 source computer loads the

ROMSIM 's resident RAM memory and

then enables data to be accessed over cables by the destination board 's byte- or word-


wide ROM circuitry. Once this code has

been debugged in the ROMSIM. burning a

single sei of PROMS completes the design editing capability and control of many

cycle. ROMSIM is a 5 x 10'' S-100 JEEE- attributes. $3500. qty discounts avail.

696 compatible circuit card. supplied with Colorgraphic Communications Corp, Suite

driver software in BASIC and FORTH. Its 105. 2379 John Glenn Dr. Atlanta. GA

RAM memory is loaded and verified through 30341 .

Circle 172

66 Digital Design JANUARY 1982

Charts, Diagrams, Etc., From DEC Printer
DECPLOT. a plug-in electronic module. provides a precis ion dot addressab le plotting feature over the e ntire page. while maintaining a ll the speed and versatilit y of the conventiona l text printing mode of the LA 120. This software conforms to the graphic protocol standards of DEC and is compatible with most DEC graphic terminal products. as we ll as w ith TEXPLOT. the portable graphics terminal based upon Tl Si lent 700 equipmen t . Only 3 simple comma nds . and none of the ASC II control characters . are required for plotting. Therefore. ex isting softwa re programs may be easi ly modified for graphi cs without rewriting systems software. It is also compatible wit h ISSCO's DISSPLA and TELL-A-GRAF. and many computer time-sharing services. DECPLOT p lu g-in modules arc $595. Texprint Inc., S Blanchard Rd . Burlington . MA OIS03.
Circle 184
Winchester Technology For PDP-11 Computers
The RASO rack-mou nt disk has a transfer rate of 1.2 MB/sec. a 25 ms average seek time. and an S.3 ms average ro~ation a l latency. Software support includes the RSX-JIM and RSX-JIM-PLUS. Three RASO drives . for a total storage capacity of

This switch selectable feature red uces the

investment costs of those buyers who are

uncertain of the precise mix o f3l01 models

required for a spec ific application. The

DM3 l0 includes: an auxi liary printer pon:

flicker free 60 Hz screen refresh: 1920

character screen presentation with a 25th

status line : 3101 compat ible keyboard with S

programmable function keys and 12 key

numeric pad: P42 green phosphor: and

ex tensive visua l and logical field attributes .

$1295: also avai lab le fo r lease or rent.

Beehive International, 4910 Ame lia Ear-

hai1 Dr. Box 2566S . Salt Lake City . UT

S4 I25.

Circle 171

VT101-AA······NEW············$995 VT131-AA EIA w/Bik. Mode. editing NEW
.....................·.·.·......... $1,575
VT100-AA EIA ···················· $1,375 LA34-DA EIA ·························825 LA34-AA EIA w/Forms·················· 875 LA34-RA EIA, Receive Only ·············· 850 LA38-GA EIA, KP, & Tractor ············1,000 LA38-HA EIA, KP, Tractor & Stand ······1,100 LA38-AA EIA, KP, Forms, Tractor & Stand 1,150 LA120-RA EIA, Receive Only···········1,795 LA120-AA EIA, KSR, Keyboard Only·····1,995 LA120-BA EIA, Keyboard & Keypad, KSR 2,075

363 MB. can be mounted in a single 40''

cabinet. Up to 4 units can be connected to a

PDP- I I computer via the µP -bascd UDA50

controller. The RASO subsystem . with one

disk drive and UDA50 controller. is

$24 .000 . Additional RASO disk drives arc

$17 .500 each. Digital Equipment Corp,

Maynard. MA 01754.

Circle 183

Offers Both Conversation And Forms Mode Operation
Designed to em ul ate the IBM 310 1. models 22 a;d 23. this display offers both conversation and forms mode operations in one unit.

Cash Prices Call Sonja at (614) 889-081 O
6145 Dolan Place - Dublin, OH. 43017
Circle 27 on Reader Inquiry Card JA UARY 1982 Digital Design 67

Power Conditioners Cut System Costs

There are essentially three types of common power line disturbances that affect computer operations: power line noise. voltage variations and power outages. Such noise disturbances and voltage variations account for 99.5% of all power-related computer problems. Of that percentage. 88.5% are noise problems. Consequently. noise-suppressing transformers have become basic peripherals in the computer industry.
Every transformer somewhat isolates one circuit from another electrically. while simultaneously coupling the two through magnetic induction . For lowgain circuits or insensitive loads. such elementary isolation is adequate. However. while power is being transferred between windings. noise potentials between the primary circuit and the ground are similarly being coupled to the secondary through capacitive resistive paths (Figure 1).
When the transformer must power a hi gh-gain circuit. sensitive instrumentation. dp or communication systems. or telemetry equipment. then primary noise must be blocked to prevent degraded or inaccurate performance. Techniques for such isolation can be considered in four steps. each providing increasing degrees of protection from the effects of noise.
First. is separation of primary and secondary coils (Figure 2). Physical separation of coils placed side by side or on separate legs of the transformer's magnetic core will provide far less capacitive coupling than coils wound directly over one another. Although greater physical separation of coi ls produces less noise coupling. it also increases leakage inductance and results in reduced power transfer. thus limiting the effectiveness of this technique.
Second. is the Faraday shield (Figure 3). A grounded single tum of conductive foil placed between coils diverts much of the primary noise current to ground . Capacitance around the Faraday shield will still couple enough noise from primary to secondary to cause problems in sensitive equipment.
Third. is the box shield (Figure4). It completely encloses the winding with a

...,._--t.. Noise Currents

~ C (Coupling Path)

Interline Capacitance
No ise Generator
Noise Currents



Capacitance and Leakage

to Ground

Figure 1: Along with power transfer, noise also passes through resistive and capacitive paths from primary to secondary and from secondary to primary. For higher-gain circuits or sensitive loads, this solution is inadequate.

Noise Cu rrents ·

.. c

Noise Generator


Figure 2: Smaller interwinding capacitances result from greater separation of primary and secondary coils. Physically separating coils lessens noise coupling but increases leakage inductance.

Noise Currents ..,.

.. c

Noise Generator

Faraday Shield


Figure 3: Noise is shunted to ground through a Faraday shield.

68 Digital Design JANUARY 1982

c .. · Noise Currents

reduction. an 8% reduction and. in very severe cases. a 10% reduction in voltage.

· Voltage sags and surges are

;:-------- -- -.,




I __________ "C.-,




.. I ....1. ------1· I

caused by faults on the power line and the resultant actions of fault-clearing devices. or by heavy loads on the power line (e.g .. machine start-up) and the slow reaction time of utility regulating equipment.
The most common solution for volt-

age variations has been the AC line

Noise Generator

voltage regulator. Whether it's a ferro-


resonant device or a sophisticated tap changer. results are similar: incoming

voltages up to 13% above nominal and

down to 25% below nominal are regu-

Figure 4: lnterwinding capacitance is further reduced through use of a box shield.

lated to within an acceptable standard. perhaps ±7% of nominal. Today.

however. the voltage regulator is being

displaced by the power conditioner. a


-----, I I

~--¢:-- 1

r· .._


unique device that combines an "UltraIsolator" (or Ultra-Isolation transformer) with a voltage regulator to produce








... ·..,.

L ____ _


the most effective counter-weapon against noise and voltage variations yet devised . These new power conditioners

Metallic Enclosure

are available in a wide variety of shapes and sizes. and in power ratings to suit

most computer systems. They are rea-

Figure 5: Shielding in an "Ultra-Isolator" or "Ultra-Isolation Transformer" is more sophisticated, isolating noise bidirectionally.

sonably priced and feature excellent efficiency. which helps lower operat-

ing costs. Power conditioners can solve

conductive foil and provides a ground drops between the utility substation 99 .5% of all power disturbances.

path for primary circuit noise. Its and the user's service entrance. These according to IBM researchers .

advantage is that a much smaller capac- voltage drops result from normal

It's also necessary to protect against

itance exists between primary and transmission line impedances that cre- blackouts. which account for only 0.5%

secondary coils than in the case of a ate lower voltage as the distance from of power line disturbances yet are

simple Faraday shield.

the utility substation increases and as devasting occurrences that can wipe out

Fourth. the "Ultra-Isolator" or the load increases.

entire programes in a matter of milli-

Ultra-Isolation Transformer (Figure · Intra-building voltage drops seconds.

5), is the ultimate step in noise isola- between the service entrance and the

The most common sol ution to black-

tion. This triple box shielded trans- distribution panels. and from the distri- outs. the UPS. falls into two categories:

former with coil separation stops noise bution panels to the point of usage. on-line UPS and off-line UPS .

currents from crossing the transformer These result from normal impedances

A typical on-line UPS has an isola-

in either direction. Each coil is com- found in cables. connectors and fuses. tion transformer. rectifier. battery

pletely enclosed in a wrapped foil box · Brownouts are initiated by the utili- charger. battery. static inverter and

shield. Transformer enclosure and ties during periods of high demand for transfer switch. Figure 6 illustrates

separator plates (special types of power. Typically. these reductions are system operation. When the AC mains

Faraday shields made from electro- regulated in stages beginning with a 3% power is normal. power is passed

statically coated aluminum) provide a reduction. then progressing to a 5% through the isolation transformer. where

second level of complete box shielding.

In addition. transformer coils are

physically separated for greater noise

attenuation. This provides the greatest

System Bypass Line

noise isolation available and protects

against 88 .5% of all error-producing power anomalies.

Static Inverter

Voltage variations must be eliminat-

AC Mains Power

ed. Although undervoltages and over-

voltages account for only l I% of the significant power line disturbances. they are blamed for over 50% of all

On-line UPS Block Diagram

power-related computer problems . The

most common reasons for voltage vari-

ations are as follows. · Normal transmission line voltage

Figure 6: The typical on-line Uninterruptible Power Source has seven functional categories, as shown.

JANUARY 1982 Digital Design 69


22-25, 198~


This 4-day Conference & Exhibit emphasizes:

· Measurement technology to improve wafer processing yields ~ :"

· Theoretical and empirical bases of measurement techniques \

· Operation and programming of measurement tools


· Data handling - its analysis, display and interactive coupling _...._...__.___ _...z;.._ _ _..!-.._ __...:._---1

Technical papers and workshops offer state-of-the-art information on such topics as:

· Measurement and analysis tools: SIMS, Auger microscopy, SEM and microprobe
· Ion implantation, doping and damage measurements
· VLSI photomasking measurements · Photoresist measurements and control · Measurement and control in projection aligners · Linewidth measurement: equipment; techniques;
edge recognition; focus sensitivity; "standards" · Laser annealing measurement and control

· Techniques to measure and control interface and insulator charge states
· Dry processing and plasma end-point measurements ·Toxic gas monitoring: chemical trace level/particle
counter for VLSI/bubble memory production · Intelligence in measurement tools · Facilities: measurements and controls · On line measurement systems for Si/Al, P/silox,
Ni/Fe · Automatic inspection for photomasks

For more information return the coupon below to Registrar, Microelectronics Measurement & Test Conference, Morgan-Grampian Expositions Group, 2 Park Avenue . New York, NY 10016 (212) 340-9700
--------------------------------------00 1/82 Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __

TCiotlme p- any-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_- _- _- _- _- _- _- _- _- _- _- _- _- _- _- _- _- _- _- _~ _

Address _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _~

- City _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.State _ _ _ _ _~·,p - - - - - - - - - -





Retum to Registrar


l 1







Morgan-Grampian Expositions Group, 2 Park Avenue, New York, NY 10016 (212) 340-9700

_ Designers' Notebook
the ex treme ly low interw inding ca paci tance eliminates hi gh-speed. hi gh-a mplitude line transients. The tra nsform er output is fed to the rectifi er where AC power is converted to DC. The static in verter converts the DC input bac k into AC to dri ve the critical load.
AC main s power is also converted to reg ul ated DC by the battery charger. maintainin g the battery in a full y charged state. The reg ul ated battery vo ltage is iso lated from the rectifier o utput/in ve rter input by a power SCR .
If the AC main s vo ltage fa lls below a predetermined leve l. the SCR turns on. co nnectin g the battery to the inverter in put. The stored energy at the rectifier is suffi cient to prov ide power to the inve rter durin g tum -on of the SCR so that no discontinuity of power is seen.
When AC mains power is restored , th e in verter is aga in automaticall y supplied with DC powe r from the rectifier. The SCR is then turned off and the battery is automatically recharged to ensure powe r to the criti cal load during the next AC main s outage. Should the monitor se nse loss of AC vo ltage at the in verter

Battery Charger - Battery


L ine
AC 0 - - - - - - - 4 1 - - - - - - - - - - -......J.....-------O AC


Off-line ups

Block Diagram


Figure 7 : The typical off-line UPS system is configu red as shown .

output. a transfer switch automatica ll y transfers the load to the AC mains.
Typical off-line PS systems are arran ged with the load nom1ally dri,·en by the AC line (Figure 7). Loss of line vo ltage is detected by a monitor that automatica ll y initiates transfer of the load to the in verter output. Power to the in ve rter is suppli ed by the batteries. When the line vo ltage is re-establi shed. the load is automaticall y transferred back to the AC line and the battery charger recharges the batteries fo r protecti on against subsequent line failures.
As for the relati ve effecti ve ness of eac h of the pre viously di scussed dev ices when it comes to protecti ng equipment from common power line

probl ems. keep the foll owing points in mind. Power conditioners and UPS syste ms are the most comprehensive . UPS kee p the computer operational durin g blackouts : but. because blacko uts acco unt for only 0 .5% of power line disturbances. the power conditioner is pro bably the most log ical choice fo r most computer app lications es peci all y where cost is a primary considerati on. Power condi tioners cost approx imate ly 45ct per VA . UPS cost approx imatel y $2.50 per VA .
by Patrick K. Hallinan
Topa::. . Inc.. 3855 Ruffin Rd.. San Diego. CA 92 123.

We're Looking
For Authors...
S tarti ng January I. 1982 . we will pay author' an honor:irium fo r artic le' and De, igners Notebooks submitted afie r th i-, da te at a rate of $35 to $75 per printed page for featu re art icle' and $70 for De, i\! ner' · Notebooks. The exact amo unt depend' upon how we ll the artic le is wri tten and organized. the amount and qua lit y of artwork <we prefer camera-ready art. but it ·' not e" cnt ia l). and how much extra wo rk must be do ne by our ed it or' and arti ' h on your text and fig ures . Upo n rece ipt of your art icle. we will ma il you an .. ack nowledge ment of rece ipt. ·· After a rc\'iew. your article will be accepted. re_iec tcd. or tentati,·cly ac cepted 1-,ub_ject to you r revi-,ions). Upon publicat ion of your artic le. you "II recei \'e a complimentary magaz ine copy and yo ur check. Topics. What do we want'? Prob lem and solution topic-, include. but are not limited to: microcomputers. minicomputer' . bu,es and interface' . power 'upplie'>. ,oftware (Ada. Pascal. a"e mbly. etc. ). printer'. plotter-, . tape drive,. fl oppy and hard disk drives. \'nice 1/0. \'idco di-,p lay term inal.. . microcomputer deve lopment "''tcm-,. lo\!ic analvzers . etc. Occas ionall v. we also run ' ubn~ i tted engit~ee r i n g 1~1a n age m ent and produc-t buying guides. The technica ll y .. hea\'ier.. your art icle i,. the more we la nd our reader' ) like it.
Guidelines. For gu ideline' to Digital Design article requireme nt,. format. 'ubmi'>'ion and acceptance. write to: Features Ed itor. Digital Design, 1050 Commonwealth Ave. Boston. MA 022 15.




Storage System

Offers superior performance, throughput and reliability!
Compatible with: ·D.E.C. ·Data General ·Westing house

The non-rotating MaxiRam is a solid -state disc replacement storage system that operates at the speed of main memory. It is ideal for the following : ... if your processor is disc 1/ 0 bound. ... if your CPU spends too much time in the 'wait' state. ... if your present disc gives you reliability headaches.
Write or call to find out how your memory performance and reliabil ity can be dramaticall y improved. Units available in both core and semiconductor.

I " " " Imperial Technology, Inc.


831 S. Dougl as Street · El Segundo,

-...,;>' Cal iforn ia 90245 · Telephone : (213) 679-9501

Circle 28 on Reader Inquiry Card

JAN UARY 1982 Digital Design 7 1

Coming Up
Color Graphics
Whether you' re des igning a color graphics system or specify ing one fo r your own use, February 's Digital Design fi lls you in on the fac tors you' II need to consider before you act. Rapid ad vances in color graphics, espec ially in the area of price/ performance, have opened up many new, previously impractical applications. As a res ult , color graphics system design has become a topic of considerable importance, both fo r engineers who des ign them and those who des ign with them.
Printing Terminals
Printing terminals fo r use in data communications represent one of the most active segments of the fas t-mov ing printing industy. February's issue covers the latest technolog ies, as we ll as the most crucial technical marketing co ns id erati o ns.

Mode l MAP-20P is a 20 co lum n. alphanumeric panel mount primer 1ha1 accepts 8 bi! TTL parallel data al rates > 2000 C.P.S . Co mplete with µ.P controlled ti ming. character ge nerati on. pri nthead-dri ve. stepping - motor c irc uits . the un it also has its own se lf- rest program a nd AC power supply. Weigh! is 4. 2 lbs. and panel space is 14.8 sq. inches . Price is $625.00 and in stock:
220 Reservoir Street Needham Hgts .. MAU2 194 617-444-7000 Te lex 92-2537
Circle 24 on Reader Inquiry Card
Looking for something but c-an't quite re-
member where?Check the Product Index
on page 52.

3 Mail to: Circulation Manager

Digital Design


I 050 Commonwealth Ave

Boston, MA 02215

Ampex-Me mory Products Div. . ..................43
AT E Co urses . . .. . ...... . .55 ATE Seminar/Exhibit .... 21.6 I
Bo-S herrel . .. .... . .... . . .57 Braege n MPD .............45
CalCo mp . . . .......... . ... I Clary .... .. ... . ... .. .. ...50 Contro lled Powe r .. .... .... C3
Datafu sion ....... . . . ..... I I Dataram .......... . .......7 Distri buted Computer
Systems ............. .. .57 Distributed Logic (Dilog) ..... 3 Dolc h Log ic Instruments .... C4
Everest Electronic Eq uipme nt ......... . .. . .56
Exatro n .................. 5 I
G ould-Deltec ..............9 G ri nne ll Systems ... . ....... 5

Ha milton Standard (Electronics) .............63
Imperial Tec hnology ..... . .7I
Kennedy ................C2
Leggett & Platt. EST Di v....65
Me modyne ....... .... ....72 Modgraph ....... .. ....... 39 M .M .T . ' 82 Conference ....70
Omega Sales ........... . .. IO
Peritek ................. .49 Porelon ............. ..... 27 Profess ional Data Systems ...5 I
Sche re r's Mini Computer Mart .. . .. ..... . . . . . ....67
Sky Computers .......... . .65
TEC .... . . . ............. I3 Tele Video Systems ...... . . I5
Ze ndex ................. . .2

Sales Offices
Northeast: John Moon (617) 232-5470, 1050 Commonwealth Avenue, Boston, MA02215
Middle Atlantic/Southeast: Ben Rowe (212) 340-9700, Morgan-Grampian Publishing, 2 Park Avenue, New York, NY 10016
Midwest: Hank Bean (312) 475-7173, 2633 Hillside Lane, Evanston, IL 60201
South Central: Jerry Ambroze (718) 780-3326, Ambroze and Associates, 2186 Augusta, Houston, TX 77057
Northwest: Dwight L. Schwab, Jr. (408) 371-9620, 1901 S. Bascom, Suite 1005, Campbell , CA 95008
Southwest: Lindy Dolan (213) 981-3300, 15910 Ventura Boulevard, Suite 1215, Encino, CA 91436
Japan: K. Yanagihara (03) 350-0272, 10-10 Shinjuku 3-chrome, Shinjuku-ku, Tokyo 160, Japan Cable Address : YanacourTokyo

72 Digital Design JANUARY 1982



advanced logic analysis

48 to 96 Cha11nels, 300MHz,plus Mnen1011ics

Order up your parameters. Dolch's LAM 4850A logic analyzer makes it easy with a new key- Monitor. Monitor gives you status information and comments on menu setups, and can be called up at any time to interpret each parameter, its range , and its interaction with the current setup. And , you can store your setups for three months without power, eliminating the need to reprogram.
Zero in fast. The LAM 4850A disassembles your code into Mnemonics an~ogives you the channels you need to trace data , address, port and control lines. And foL future needs , you can expand to 64, or even 96, channels.

Hook up fast, too. Dolch personality probes clip right over -your CPU chips so you don't waste time connecting dozens of individual hooks . And the probe takes care of clock , timing and signal interfacingno need to worry about signal conditions.
300 MHz sampling across 16 channels. A revolutionary option gives you the ultimate in sampling resolution - 3 .3 ns to help you solve the toughest timing and phase related problems. A unique memory overlay configuration provides simultaneous dual asynchronous recording across 16 channels without compromising any of the LAM 4850A features.
Circle 2 on Reader Inquiry Card

Don't settle for less than Dolch. The._

basic LAM 4850A is truly a universal

logic analyzer system with 50 MHz sam-

pling rate , 1000 bits per channel source

and reference memories, and sophisti-

cated sequential trigger and multilevel ~



For details on the Dolch LAM 4850A, or

any of our other troubleshooting tools, <.

write: Dolch Logic Instruments , Inc ., 230

Devcon Drive, San Jose, CA 95112. Or '

call toll free: (800) 538-7506; in Califor-

nia call (408) 998-5730.

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