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User Manual: Altair Clone Operator's Manual

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ALTAIR 8800 CLONE COMPUTER

OPERATOR’S MANUAL

Version 2.1, April 2017

TABLE OF CONTENTS

INTRODUCTION ............................................................... 1

PART 1 – ALTAIR 8800 CLONE HARDWARE SPECIFICATIONS ......................... 2

PART 2 – CONFIGURATION MONITOR ............................................. 4

A. Floppy Disk Menu ....................................................... 4

B. PROM Menu .............................................................. 6

C. Serial Port Menu ....................................................... 7

D. Load .BIN or .HEX File ................................................. 9

E. Administration Menu .................................................... 9

PART 3 – TERMINAL EMULATOR ................................................ 14

A. Overview .............................................................. 14

B. TeraTerm Terminal Emulator ............................................ 14

C. Installing TeraTerm ................................................... 14

D. Configuring TeraTerm .................................................. 14

E. Using TeraTerm ........................................................ 15

PART 4 – ALTAIR 8800 DEMONSTRATIONS ....................................... 16

A. Kill-the-Bit Front Panel Game ......................................... 16

B. Loading and Using 4K BASIC from Paper Tape ............................ 18

C. Loading and Using 8K BASIC from Cassette .............................. 21

D. Loading and Using Disk BASIC from Floppy Disk......................... 25

E. Loading and Using Altair DOS .......................................... 27

F. Loading and Using CP/M ................................................ 30

G. Loading and Using Timesharing BASIC ................................... 32

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INTRODUCTION

The original Altair 8800 is the best computing platform available for reliv-

ing the birth of the personal computing revolution. You will find your new

Altair Clone to be the next best thing!

For most users, the Altair computing environment of today is, out of neces-

sity, slightly different than the computing environment of the mid 1970s.

However, once familiar with these differences, you can follow right along

with Altair owners of the 1970s – even using original Altair documentation

and software - to experience first-hand the thrill of using these early per-

sonal computers.

NEXT STEPS

The best way to proceed from here is up to you!

If you want as real an Altair experience as possible, first, understand the

hardware configuration of your Altair 8800 (Part 1, “Altair 8800 Clone Hard-

ware Specifications”), second, learn how to modify that configuration if

needed (Part 2, “Configuration Monitor”), then proceed from there using orig-

inal Altair documentation and software.

Original documents and supporting software are under the Support link on the

AltairClone.com website. It is recommended that you download the full Clone

support package by clicking on the Support Package link, then extracting all

files to your disk. Start your research by looking at the “Altair 8800 Opera-

tor’s Manual.” Keep in mind that all the manuals contain a mistake or two (or

more!) and may send you down the wrong path at times – that’s part of the

fun!

If you want some help along the way, the Altair Experience link on the Al-

tairClone.com website provides a great list of topics and tutorials you may

want to work through on your Altair Clone.

If you want to quickly set up a few popular Altair demonstrations, Part 4,

“Altair 8800 Demonstrations” gives step-by-step instructions for the follow-

ing activities:

• Kill-the-Bit front panel game

• Loading and using 4K BASIC from paper tape

• Loading and using 8K BASIC from cassette

• Loading and using Disk BASIC from floppy disk

• Loading and using Altair DOS

• Loading and using CP/M

• Loading and using Timesharing BASIC

- 2 -

PART 1 – ALTAIR 8800 CLONE HARDWARE SPECIFICATIONS

A. RAM

64K of RAM with memory protect in 256 byte pages. If any PROMs are loaded and

enabled, the overlaid RAM is replaced by PROM in 256 byte increments.

B. PROM

Eight “sockets” of up to 2K each provide for up to 16K of PROM. Loaded and

enabled PROMs overlay and replace RAM in 256 byte increments. A feature pre-

sent in the 8800b Turn-Key computer to disable PROM (in order to re-enable

RAM) can be turned on if desired. See “Administration Menu” in Part 2, “Con-

figuration Monitor” for more information.

C. Serial Ports

Two serial ports are wired to DB-25 connectors on the rear of the computer.

The port types can be configured to match original Altair hardware as shown

below. The optional Audio Cassette Interface adds the third serial port. The

first row illustrates the default configuration.

Serial Port 1

(Top Connector)

Serial Port 2

(Bottom Connector)

Serial Port 3

(from Cassette Intf)

First port from 88-2SIO

board at I/O address oc-

tal 20/21

88-SIO port at I/O ad-

dress 6/7 (the Altair

cassette serial port)

First port from a second

88-2SIO board at I/O ad-

dress octal 24/25

88-SIO port at I/O ad-

dress 0/1

Second port from 88-2SIO

board at I/O address oc-

tal 22/23

88-SIO port at I/O ad-

dress 6/7 (the Altair

cassette serial port)

The serial ports are wired as follows:

Pin Signal

XMT from Terminal (out) to Clone (in)

RCV to Terminal (in) from Clone (out)

RTS from Terminal (out) to Clone (CTS in)

CTS to Terminal (in) from Clone (RTS out)

Signal Ground

By default, pin 4 RTS (which becomes CTS inside the Clone) is always asserted

inside the Clone and therefore does not need to be connected on the DB-25 if

active handshaking is not used. RTS is not present or used on Port 3.

By default, pin 5 CTS (which is driven from RTS inside the Clone) is always

asserted in case an asserted handshake signal is required by the peripheral

device. CTS is not present or used on Port 3.

The ACIA on the 88-2SIO board supports programmed hardware handshaking. If

your applications requires this feature, the ACIA’s handshake lines can be

configured to be fully active. See “Set CTS, RTS Usage” in the “Serial Port

Menu” section of Part 2, “Configuration Monitor” for more information.

D. Line Printer Port

The Altair Clone implements the Altair 88-LPC (Okidata) and 88-C700 (Cent-

ronics) line printer interface boards. In the Altair Clone, data sent to ei-

ther of these printer boards is transmitted out serial port 2, which in turn,

can be connected to a terminal emulator window to view printer output, or

- 3 -

connected directly to a serial printer. Normal serial port functions of port

2 still work when routing printer output through the port. For example, se-

rial port 2 can be used as the cassette interface to load and save programs

and also for line printer output.

See “Line Printer Controller” in the “Administration Menu” section of Part 2,

“Configuration Monitor” for more information.

E. Floppy Drives

The Altair Clone provides three floppy “drives” that duplicate the function-

ality of the original Altair 8 inch floppy drives or the Altair Minidisk 5.25

inch drive. Floppy storage is implemented using non-volatile RAM inside the

Altair Clone. Since physical floppy disks and drives are not present, “in-

serting” a floppy disk is done by uploading a floppy image from a PC to the

Clone. Conversely, a floppy image on the Clone can be saved back to a PC for

archiving.

Once uploaded to the Clone, floppy disk content is non-volatile and further

data exchange with a PC is not required to use the floppy drives. Floppy

disks can be swapped between the three drives (to put a different disk into

drive zero to boot, for example) without having to connect to a PC. The “Con-

figuration Monitor” makes floppy disk handling simple. See “Floppy Disk Menu”

in Part 2, “Configuration Monitor” for more information.

F. Interrupts and the 88-VI/RTC Board

Interrupts in the Altair 8800 Clone can be generated by the serial ports

(2SIO and/or SIO), the floppy disk controller ("sector true" interrupt at the

start of each sector), the real-time clock present on the 88-VI/RTC board,

and by the 88-C700 Centronics printer interface.

The 88-VI/RTC Vectored Interrupt/Real-Time Clock board prioritizes interrupts

to the 8080 processor from the vectored interrupt lines (VI0-VI7) on the Al-

tair bus. The board can also provide 60hz real-time clock interrupts. While

not widely used for most commercial software, the VI/RTC board is required by

MITS Time-Sharing BASIC for the Altair.

If the 88-VI/RTC board is not enabled, then the default interrupt structure

of the Altair (PINT with RST7) is used. In this case, all devices can be tied

into the PINT line at the same time as the emulated devices all drive the

PINT line with open collector outputs. As with the original hardware, all

boards (other than the 88-VI/RTC) ignore the 8080 interrupt acknowledge cy-

cle, so the 8080 processor sees a RST7 instruction on the bus (all data bits

high) during the interrupt acknowledge cycle.

Connection of device interrupt outputs to the desired vectored interrupt line

on the Altair bus (VI0-VI07) is done in the “Interrupt Vector Assignments”

menu of the “Administration Menu.” See these menus in Part 2, “Configuration

Monitor” for more information.

G. Changing Hardware Configuration

If an original Altair owner needed to install a new serial I/O card, install

or remove a PROM, or change a baud rate jumper, the owner opened the computer

and made the required modifications inside the computer. In the Altair 8800

Clone, these hardware configuration changes are made using menu options in

the “Configuration Monitor.” See Part 2, “Configuration Monitor” for more in-

formation.

- 4 -

PART 2 – CONFIGURATION MONITOR

The Configuration Monitor is used to manage the physical and virtual hardware

in the Altair 8800 Clone. The monitor is a simple menu driven program built

into the Clone. Communication with the operator is always via serial port 1

at 9600 baud, 8N1.

To enter the Configuration Monitor, raise and hold the STOP/RUN switch in the

STOP position, then raise the left AUX switch. The main menu is displayed:

=== Configuration Monitor 1.91 ===

1) Floppies

2) PROMs

3) Serial Ports

4) Load .BIN

5) Load .HEX

6) Admin

x) Exit to Altair

IMPORTANT: Exiting the Configuration Monitor and returning to normal Altair

operation should always be performed by backing out of sub-menus to the main

menu shown above, then choosing the “Exit to Altair” menu option.

A. Floppy Disk Menu

The floppy disk menu is used to insert, remove and manage floppy disks. Flop-

py disks are byte for byte images of actual Altair floppy disks and are ini-

tially uploaded to the Clone from a PC. Floppy disk content is stored in non-

volatile RAM inside the Clone and once uploaded, is always available.

When the floppy disk option is selected from the main menu, the content of

each drive is shown. The drive numbers listed are the same drive numbers used

with real Altair drives.

=== 8 Inch Floppy Drive Content ===

Drive 0: CP/M 2.2

Drive 1: Disk BASIC Games

Drive 2: Altair DOS

Drive to Update (x to exit):

When a drive number is selected, the following menu is displayed:

=== Floppy Drive Menu ===

1) Change Drive Number

2) Load Floppy from PC

3) Save Floppy to PC

4) Change Description

x) Exit Menu

1. Change Drive Number

The “Change Drive Number” option is used to change which drive a floppy disk

is in. This is typically used to put a different disk into drive zero for

booting. The selected disk is swapped with the disk presently in the destina-

tion drive number.

2. Load Floppy from PC

The “Load Floppy from PC” option is used to load new content into a drive.

The floppy disk image is uploaded from a PC using the XMODEM protocol (origi-

- 5 -

nal XMODEM with 128 byte blocks and checksum). Compatible disk images files

typically have a “.dsk” extension and are 330K or 75K in size (8 inch, mini-

disk respectively).

The floppy image transfer is done at a higher baud rate to reduce the trans-

fer time. The default transfer rate is 115,200 baud. This rate can be changed

using the “Floppy Drive Settings” option in the “Admin” menu. An option to

transfer the file over the second serial port instead of the default console

port is also available in this menu.

Upon selecting the load floppy option, the monitor confirms the operation and

prompts for a description of the new disk. The PC baud rate should then be

set to 115,200 baud after which the XMODEM send operation can be initiated on

the PC. If using TeraTerm, a convenient shortcut is pressing CTRL-1 to set

the baud rate to 115,200 baud. The new baud rate can be seen in the TeraTerm

title bar.

When the transfer completes, the user is prompted to return the PC baud rate

to 9600 baud. If using TeraTerm, a convenient shortcut is pressing CTRL-9 to

return the baud rate to 9600 baud. The new baud rate can be seen in the Ter-

aTerm title bar. This sequence is shown below:

=== Load Floppy from PC ===

This will over-write "Altair DOS." Are you sure (y/n)? y

Floppy description: New Disk

Step 1: Set console baud rate to 115.2K

Step 2: Start XMODEM file SEND after setting the new baud rate...

(XMODEM transfer occurs here...)

Return console to 9600 baud, then RETURN:

If the XMODEM transfer must be aborted, first stop the transfer from the PC

end, then abort the Clone’s reception by raising and releasing the left AUX

switch.

3. Save Floppy to PC

This menu option is used to write a floppy disk image back to a PC for ar-

chiving. The floppy disk image is downloaded to the PC using the XMODEM pro-

tocol (original XMODEM with 128 byte blocks and checksum). The floppy image

transfer is done at a higher baud rate to reduce the transfer time. The de-

fault transfer rate is 115,200 baud. This rate can be changed using the

“Floppy Drive Settings” option in the “Admin” menu. An option to transfer the

file over the second serial port instead of the default console port is also

available in this menu.

Upon selecting the save floppy option, the monitor confirms the operation and

prompts for the baud rate change. The PC baud rate should be set to 115,200

baud after which the XMODEM receive operation can be initiated on the PC. If

using TeraTerm, a convenient shortcut is pressing CTRL-1 to set the baud rate

to 115,200 baud. The new baud rate can be seen in the TeraTerm title bar.

When the transfer completes, the user is prompted to return the PC baud rate

to 9600 baud. If using TeraTerm, a convenient shortcut is pressing CTRL-9 to

return the baud rate to 9600 baud. The new baud rate can be seen in the Ter-

aTerm title bar. This sequence is shown below:

- 6 -

Save content of "Altair DOS" to the PC. Are you sure (y/n)? y

Step 1: Set console baud rate to 115.2K

Step 2: Start XMODEM file RECEIVE after setting the new baud rate...

(XMODEM transfer occurs here...)

Return console to 9600 baud, then RETURN:

If the XMODEM transfer must be aborted, first abort the Clone transmission by

raising and releasing the left AUX switch, then stop the receive operation on

the PC end.

4. Change Floppy Description

Use this menu option to change the description of a drive’s content. This can

also be used to eject a floppy you’re no longer using by changing the de-

scription to “Scratch Disk” (or any similar description) to indicate the

drive is free to use. From the Altair’s perspective, a floppy disk is still

present in the drive, just consider it a blank or scratch disk.

-------------------------------------------

B. PROM Menu

The PROM menu is used to insert and remove PROMs. Eight slots are provided

for PROM content. Each slot is up to 2K bytes in length. PROM content is up-

loaded from a PC in binary (.bin) or Intel Hex (.hex) format. Once uploaded,

PROM content is non-volatile. PROM content can also be disabled without actu-

ally removing the PROM so that it can later be re-enabled without having to

re-upload the content from a PC.

When the PROM Menu option is chosen from the main menu, the current content

of each PROM slot is displayed as shown below:

=== PROM Information Table ===

Num State Addr Length Description

--- --- ---- ------ -------------------

1 ON FF00 0100 Disk Boot Loader

2 ON FE00 0100 Multi-Boot Loader

3 ON FD00 0100 Turn-Key Monitor

4 OFF 0000 0000

5 OFF 0000 0000

6 OFF 0000 0000

7 OFF 0000 0000

8 OFF 0000 0000

PROM to Update (x to exit):

To load or change the content of a PROM slot, enter the slot number. The fol-

lowing menu is displayed:

=== PROM Menu ===

1) Load New Content

2) Change Description

3) Change Load Address

4) Enable PROM

5) Disable PROM

6) Remove PROM

x) Exit Menu

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1. Load New PROM Content

The “Load New Content” option is used to load new content into a PROM slot.

The PROM data can be uploaded as a binary or Intel hex format file. If a bi-

nary format is chosen, the load address must be specified (up to four hex

digits). The example below shows loading PROM content from an Intel hex file.

File transfer can be aborted by pressing CTRL-C or raising the left AUX

switch.

=== Load New Prom Content ===

Enter PROM Address in hex (RETURN for .HEX file):

Send .hex file now...

(initiate simple send file operation from the PC – not XMODEM)

2. Change Description, Change Load Address, etc.

Options 2 – 6 are fairly self explanatory. Note: The “Change Load Address”

option does NOT magically relocate already assembled code. This option is

used if you accidentally typed in the wrong address when initially loading a

binary PROM file.

-------------------------------------------

C. Serial Port Menu

The serial ports on the Altair Clone can be configured in a variety of ways

to match the requirements of the software to be run. By default, port 1 is a

2SIO port (Motorola ACIA) at octal address 020/021. Serial port 2 defaults to

an SIO port at address 006/007 (the cassette interface port). If you pur-

chased an assembled Clone, serial port 1 is the upper DB-25 on the rear panel

and serial port 2 is the lower connector. If using the optional Audio Cas-

sette Interface, you’ll probably want to configure Port 3 to be the cassette

I/O port (SIO at 006/007, 300 baud, 8N1) instead of Port 2.

When the Serial Port Menu option is chosen from the main menu, the current

serial port settings are displayed as shown below (Note: The port settings

shown are also the default settings).

=== Serial Port Settings ===

Port Type I/O Rate Other

---- ---- ------- ---- --------

1 2SIO 020,021 9600

2 SIO 006,007 9600 8N1

3 2SIO 024,025 9600

Port to Change (x to Exit):

After entering the serial port number to change, this menu is displayed:

=== Serial Port Menu ===

1) Port Type

2) Baud Rate

3) CTS, RTS Usage

4) Word Length, Parity, Stop Bits

x) Exit Menu

- 8 -

1. Change Port Type

The “Port Type” option is used to specify the type of Altair serial port as-

signed to a physical serial port on the Altair Clone. The following options

are displayed:

=== Serial Port Type ===

1) 88-SIO

2) 88-2SIO

x) Exit Menu

The SIO port type duplicates operation of the original 88-SIO boards with the

status word modification in place. These are the most common versions of the

SIO board and are referred to as “not Rev 0” or “Rev 1” in Altair manuals.

Serial port 1 is at address 0/1 and serial ports 2 and 3 are at address 6/7

(matches the SIO port used with the Altair cassette interface).

The 2SIO option duplicates operation of the 88-2SIO boards which use the Mo-

torola ACIA as the UART. Serial port 1 is at octal address 020/021, port 2 is

at octal address 022/023, and port 3 is at octal address 024/025.

2. Set Baud Rate

Self explanatory.

3. Set CTS, RTS Usage

This option only affects a serial port configured as a 2SIO port. The ACIA on

the 2SIO board allows use of handshake lines CTS and RTS. On a real 88-2SIO

board, if the user did not want these signals to affect operation, they could

be tied active or inactive as needed. This menu option allows configuration

of how CTS and RTS are used.

If CTS is set to “Always Asserted,” CTS is permanently asserted “true” going

into the ACIA. If RTS is set to “Always Asserted,” RTS is permanently as-

serted “true” going out of the DB-25 serial port connector. When either sig-

nal is set to “Used,” the signal passes from/to the serial port to the ACIA

as expected.

=== CTS, RTS Usage (2SIO Only) ===

1) CTS, RTS Always Asserted

2) Only RTS Used

3) Only CTS Used

4) CTS, RTS Both Used

x) Exit Menu

4. Set Word Length, Parity, Stop Bits

This option only affects a serial port configured as an SIO port. To config-

ure word length, parity and stop bits on a real 88-SIO board, jumper wires

were used. This menu option allows configuration of these same jumper set-

tings. When this menu option is selected, the following menu is displayed:

- 9 -

Word Length, Parity, Stop Bits (SIO Only)

1) 7E2

2) 7O2

3) 7E1

4) 7O1

5) 8N2

6) 8N1

7) 8E1

8) 8O1

x) Exit this Menu

D. Load .BIN or .HEX File

These options provide a method to directly load a program or data into Altair

memory. Files are sent using simple 8-bit transfer (not XMODEM). If a binary

file is sent, the load address (up to four hex digits) must be specified.

The example below shows loading memory from a binary file. File transfer can

be aborted by pressing CTRL-C or raising the left AUX switch.

Enter load address in hex: 0

Send .bin file now...

(initiate simple send file operation from the PC – not XMODEM)

-------------------------------------------

E. Administration Menu

When “Admin” is selected from the main menu, the administration menu is dis-

played:

=== Administration Menu ===

1) Interrupt Vectors

2) Line Printer Controller

3) Turnkey Module

4) Floppy Drive Settings

5) Single-Step "Down" Options

6) Restore Defaults

7) Update Firmware

x) Exit Menu

1. Interrupt Vector Assignments

The 88-VI/RTC Vectored Interrupt/Real-Time Clock board in the Altair Clone is

used to prioritize interrupts to the 8080 processor from the vectored inter-

rupt lines on the Altair bus (VI0-VI7). In a real Altair, a device’s inter-

rupt output is connected to the desired vector line using a jumper. This menu

allows specification of that connection.

When this menu option is selected, the present vector assignments for inter-

rupt sources in the Clone are displayed:

- 10 -

=== 88-VI/RTC Vectored Interrupt Assignments ===

Device Vector

------------- ---

1) Floppy Drives 0

2) Serial Port 1 2

3) Serial Port 2 2

3) Serial Port 3 3

4) Real-Time Clk 1

Device Number to Update (x to exit):

After specifying the device number to update, the user can choose a new in-

terrupt vector number (0-7) for the device. VI0 is the highest interrupt pri-

ority, VI7 is the lowest priority. For the Real-Time Clock only, a “D” for

“Disabled” can be entered as a vector number. This disables interrupts from

the RTC even if 8080 software enables them. Changing a Serial Port’s setting

affects whatever device is assigned to the port, e.g., 88-2SIO, 88-SIO, and

for Serial Port 2, the 88-C700 Centronics printer interface.

2. Line Printer Controller

Data sent to the 88-LPC (Okidata) or 88-C700 (Centronics) printer interface

can be routed through serial port 2, which in turn, can be connected to a

terminal emulator window to view printer output, or connected directly to a

serial printer.

Normal serial port functions of port 2 still work when routing printer data

through the serial port. For example, serial port 2 can be used as the cas-

sette interface to load and save programs and to also see line printer out-

put. One exception is that the serial port device (88-2SIO or 88-SIO) and the

Centronics printer device cannot both use interrupts at the same time. This

means, for example, when running Timesharing BASIC, you can't use serial port

2 as both a 2SIO user terminal port and the Centronics printer port at the

same time.

=== Line Printer Selection ===

Current setting: 88-LPC (Okidata)

1) 88-LPC (Okidata)

2) 88-C700 (Centronics)

3) Disable Line Printer

x) Exit Menu

3. Turnkey Module

The Altair Turnkey board can be installed or removed with this menu. The

Turnkey Module provides auto-start to a specified address (typically in ROM)

on power up or following a front panel reset.

The Turnkey Module also allows the 1K of ROM at 0xFC00 to 0xFFFF to overlay

RAM. ROM is enabled at power up and on reset. The ROM is disabled and RAM en-

abled upon execution of an IN instruction from 0xFE or 0xFF. Since 0xFF is

the sense switch port, booting from disk automatically enables all 64K of RAM

because the boot loader PROM (while executing from RAM) does an IN operation

from the sense switch port. Note that the Altair Multi-Boot Loader PROM (MBL)

fails to run properly with the Turnkey Module installed since this PROM reads

the sense switch port while executing from PROM, effectively killing itself.

- 11 -

=== Turnkey Module ===

Current setting: Disabled

1) Enable Turnkey

2) Autostart Address: FF00

x) Exit Menu

4. Floppy Drive Settings

This menu is used to configure the floppy drive type (8 inch or minidisk),

the drive performance (actual speed or faster), and the baud rate and serial

port used for disk image transfer.

=== Floppy Drive Settings ===

1) Drive Type

2) Drive Performance

3) Baud Rate for Transfer

4) Serial Port for Transfer

x) Exit Menu

4.1 Drive Type

This option is used to select between the Altair 8 inch floppy or the Altair

Minidisk. All three drives are affected. After switching drive type, be sure

to upload disk images appropriate for the drive type selected.

=== Floppy Drive Type ===

Current setting: 8 Inch

1) 8 Inch

2) Minidisk

x) Exit Menu

4.2 Drive Performance

The Altair Clone accurately duplicates the timing of the original Altair

Floppy disk drive. While authentic, the slow speed can be frustrating after a

while! This menu allows choosing between maximum speed or real speed. Actual

speed is the default setting.

=== Floppy Performance ===

Current setting: Actual Speed

1) Actual Speed

2) Maximum Speed

x) Exit Menu

4.3 Baud Rate for Floppy Load/Save

When transferring floppy data from/to the PC (see “Floppy Disk Menu”), a

higher baud rate is used to speed up the transfer process. The default trans-

fer rate is 115.2K baud. This menu allows selection of a different rate. Suc-

cessful operation at 230.4K and 460.8K baud varies greatly based on the se-

rial to USB adapter, adapter driver version, operating system, etc.

- 12 -

=== Floppy Load/Save Baud Rate ===

Current rate is 115.2K

1) 9600

2) 19.2K

3) 38.4K

4) 57.6K

5) 76.8K

6) 115.2K (recommended)

7) 230.4K

8) 460.8K

9) Exit Menu

4.4 Serial Port for Floppy Load/Save

The default port used for file transfer is the monitor console port (serial

port 1). Optionally, serial port 2 can be used for file transfer. This allows

a vintage terminal to remain on serial port 1 while using a PC or other com-

puter for disk image transfer on serial port 2.

=== Serial Port for Floppy Load/Save ===

Currently using port 1

1) Use Port 1

2) Use Port 2

x) Exit Menu

5. Single Step “Down” Options

Single step on the 8800 is performed by raising the Single-Step switch.

Pressing down on the Single-Step switch does nothing. In the 8800b computer,

however, pressing and holding the Single-Step switch in the down position au-

to-stepped at a rate determined by jumpers on the front panel board. This

menu option allows the user to choose similar features for Clone’s Single-

Steps switch. The default setting is for this feature to be disabled.

=== Single-Step "Down" Options ===

Current setting: Disabled

1) Disabled

2) Single-Step

3) 1 per sec

4) 2 per sec

5) 4 per sec

6) 8 per sec

x) Exit Menu

8. Restore Defaults

Use the “Restore Defaults” menu option to restore all options and content to

their original values.

=== Restore Defaults ===

This operation will erase all floppy and PROM content

and set all parameters to their defaults values.

Restore defaults (y/n)?

- 13 -

9. Update Firmware

The “Update Firmware” menu option is used to install a firmware update into

the Altair 8800 Clone. See also the “Cold-Start Update Procedure.”

=== Update Firmware ===

This operation updates the Altair 8800 Clone firmware.

Do not perform this operation unless you have been instructed

to perform the update.

Continue (y/n)?

Cold Start Firmware Update

If the Altair Clone is unresponsive, the firmware can be restored without us-

ing the Configuration Monitor. Terminal emulator settings for a cold start

update are the same as for the Configuration Monitor (9600 baud, 8N1). With

power off, raise and hold the left AUX switch in the up position, then turn

on power while continuing to hold AUX in the up position. After about two se-

conds, you will see the “Update Firmware” prompt shown above. The AUX switch

can then be released. Follow the prompts to complete the software update pro-

cess.

- 14 -

PART 3 – TERMINAL EMULATOR

A. Overview

A terminal emulator running on a PC is a convenient way to duplicate the

functionality of a teletype, paper tape reader/punch, CRT terminal, cassette

interface, capture printer output, etc. To provide these capabilities and

other useful functions, a terminal emulator with the following capabilities

is recommended:

• 8-bit transmission of text files (e.g., paper tape reader).

• 8-bit reception of text files (e.g., paper tape punch).

• Per character and/or per line delays when transmitting a text file.

• Terminal emulation should include an 8-bit mode in which the 8th bit is

ignored (assumed by 4K and 8K BASIC). Note, if the emulator supports a

7-bit plus parity mode in which the received parity is ignored, this

will also work.

• Support for original XMODEM (checksum) file send and receive.

B. TeraTerm Terminal Emulator

On the Windows platform The TeraTerm emulator meets all of the requirements

listed above. TeraTerm is now an Open Source project maintained at:

http://ttssh2.sourceforge.jp/index.html.en

The version of TeraTerm maintained at the link above is much newer than the

version found at the “TeraTerm Home Page.” The latter is not recommended.

C. Installing TeraTerm

Installation files for TeraTerm are available on the AltairClone.com website

under the Support link. The installation files are also included in the All

Manuals and Software as a .zip file link.

Follow these steps to install TeraTerm:

1) Extract all files from the downloaded .zip file.

2) Install TeraTerm by running the file teraterm-4.77.exe

Note: On the "Select Components" installation page, you can de-select

all optional components.

3) Copy the files "keyboard.cnf", "baud115k.ttl" and "baud9600.ttl" to the

program folder in which TeraTerm was installed.

4) Copy the file "teraterm.ini" file to the "My Documents" folder.

D. Configuring TeraTerm

When TeraTerm is launched, it loads its configuration from the "teraterm.ini"

file it finds in the "My Documents" folder. Step 4 above put a sample con-

figuration file in the “My Documents” folder. The first time TeraTerm is

started, you will probably have to select a different COM port under "Setup-

>Serial Port." After choosing the proper COM port, save the configuration by

choosing "Setup->Save setup" and over-writing the "termaterm.ini" file in the

"My Documents" folder.

- 15 -

E. Using TeraTerm

The most commonly used menu options are:

File->Send File Sends a file over the serial port with no protocol

(e.g., paper tape or cassette, or non-XMODEM “Send File” operations

in the Configuration Monitor). Be sure the "Binary" checkbox at the

bottom of the file dialog box is checked.

File->Log... Receives a file over the serial port with no protocol

(e.g., paper tape or cassette). Be sure the "Binary" checkbox at the

bottom of the file dialog box is checked. When the file log operation

is started, a new taskbar tile appears (TeraTerm:Log). When file re-

ception is complete, click on the log taskbar tile and then click the

“Close” button to complete the file receive operation.

File->Transfer->Xmodem Used to send and receive files using the XMODEM

protocol. The Configuration Monitor uses XMODEM transfers to exchange

floppy disk content with the Clone. Also, the CP/M utilities “PCGET”

and “PCPUT” use the XMODEM protocol to transfer files between the Al-

tair and a PC.

Setup->Serial Port... Used to change baud rate, bits, parity, delay per

character and line, etc.

The following keyboard macros are enabled if step 3 was done correctly during

installation:

CTRL-1 changes to 115,200 baud (for transferring floppy content)

CTRL-9 changes to 9,600 baud (default baud rate)

Note: The current baud rate is visible in the title bar of the TeraTerm win-

dow.

- 16 -

PART 4 – ALTAIR 8800 DEMONSTRATIONS

This section contains step-by-step instructions for several popular Altair

demonstrations. These demonstrations assume you have downloaded the support

package from the AltairClone.com website: Click on the Support link at the

top of any page, then click on the All Manuals and Software as a .zip file

link. Extract all files from the zip file to your computer.

These demonstrations just scratch the surface of what can be done and learned

with your Altair 8800 Clone. Be sure to dig through the documentation and

software provided in the downloaded support package – you will find a wealth

of useful manuals and software. Keep in mind that some of the software is

“hidden” on Altair floppy disk images that can be seen only after the floppy

is loaded on to the Altair. This includes files on Altair BASIC disks, the

Altair DOS disk and on CP/M disks.

A. Kill-the-Bit Front Panel Game

Kill the Bit was one of the first games for the Altair. It runs on the front

panel of the Altair and does not require connection to an external teletype

or terminal. Following is the assembly language listing of the program:

;

; Kill the Bit game by Dean McDaniel, May 15, 1975

;

; Object: Kill the rotating bit. If you miss the lit bit,

; another bit turns on leaving two bits to destroy. Quickly

; toggle the switch, don't leave the switch in the up

; position. Before starting, make sure all the switches

; are in the down position.

0000 org 0

0000 210000 lxi h,0 ;initialize counter

0003 1680 mvi d,080h ;set up initial display bit

0005 010E00 lxi b,0eh ;higher value = faster

0008 1A beg: ldax d ;display bit pattern on

0009 1A ldax d ;...upper 8 address lights

000A 1A ldax d

000B 1A ldax d

000C 09 dad b ;increment display counter

000D D20800 jnc beg

0010 DBFF in 0ffh ;input data from sense switches

0012 AA xra d ;exclusive or with A

0013 0F rrc ;rotate display right one bit

0014 57 mov d,a ;move data to display reg

0015 C30800 jmp beg ;repeat sequence

0018 end

To run the program, it must first be entered into the Altair’s memory using

the front panel switches. The front panel switches are grouped such that data

entry from an octal dump is easiest. Following is a dump of each byte of the

program in octal:

- 17 -

Addr Data

---- ----

Addr Data

---- ----

Addr Data

---- ----

000 041

001 000

002 000

003 026

004 200

005 001

006 016

007 000

010 032

011 032

012 032

013 032

014 011

015 322

016 010

017 000

020 333

021 377

022 252

023 017

024 127

025 303

026 010

027 000

Follow these steps to enter the program:

1) Turn the power switch on.

2) Raise and hold the STOP switch in the STOP position, then raise and re-

lease the RESET switch. Finally, release the STOP switch. This performs

a hard reset on the computer and sets all address lights to zero.

3) Put the first data byte in switches 7 through 0, then raise DEPOSIT.

4) Put the data for the next address in switches 7 through 0, then depress

DEPOSIT NEXT.

5) Repeat step 4 until all bytes have been entered.

6) Raise and release RESET to force all address lights back to zero.

7) Verify the data shown on lights D7 through D0 matches the data byte for

the current address. If the value is correct, go to step 9, otherwise

go to step 8.

8) Put the correct value in switches 7 through 0, then raise DEPOSIT.

9) Depress EXAMINE NEXT

10) Repeat steps 7 through 9 to validate entry of the entire program.

Once the program is entered, you’re ready to play Kill the Bit! Read the in-

structions in the program listing above, then follow the steps below to run

the game.

1) Set all address switches to zero.

2) Raise EXAMINE (or raise RESET) to set all address lights (and the 8080

program counter) to zero.

3) Depress RUN to run the program.

To start the game over, raise and release RESET. To change the rate at which

the light moves, change the byte at address 6 from 016 to a different value.

Higher values move the light faster, lower values move the light slower.

- 18 -

B. Loading and Using 4K BASIC from Paper Tape

In this demonstration, we will load 4K BASIC Version 3.2 from paper tape. In

the mid-1970’s, a teletype connected to single serial port on the Altair

would have served as both the console and paper tape reader. We will dupli-

cate this configuration using a terminal emulator on a PC as both the console

and paper tape reader.

Computer Configuration

For this exercise, serial port #1 on the Altair Clone (the upper DB-25

connector) should be configured as a 2SIO port at octal I/O address 20/21.

This is a standard Altair configuration. This is also the default Altair

Clone configuration. You can confirm or change the Clone’s serial port

configuration if needed. See “Serial Port Menu” in Part 2, “Configuration

Monitor” of this manual.

The default baud rate for the serial port on the Clone is 9600 baud. While

this is much faster than the 110 baud at which a real teletype operates,

we recommend using 9600 baud for this demonstration. Buffering in the PC’s

serial port drivers and issues with some USB-to-Serial adapters can make

operation at 110 and 300 baud problematic.

Terminal Emulator Configuration

The TeraTerm terminal emulator is used to duplicate the functionality of a

teletype. Confirm serial settings of 9600 baud, 8 bits, no parity, one

stop bit (8N1) in the “Setup->Serial Port” menu in TeraTerm. Also confirm

that the “Transmit Delay” fields are both set to zero.

To load 4K BASIC, we must first enter a small program via the front panel

called a “bootstrap loader.” The job of the bootstrap loader is to receive a

second loader from paper tape called the “checksum loader.” The checksum

loader is at the beginning of the BASIC paper tape. Once the checksum loader

has been read into memory, the checksum loader then reads in BASIC from the

remainder of the paper tape.

The code for the bootstrap loader is provided by Altair in the BASIC manual.

Different versions of the bootstrap loader are required based on the version

of BASIC and the type of interface card being used. For this demonstration,

we need the bootstrap loader for the 88-2SIO serial board and for 4K BASIC

Version 3.2. Following is the bootstrap loader code for this combination of

BASIC and serial port type:

Addr Data

---- ----

Addr Data

---- ----

Addr Data

---- ----

Addr Data

---- ----

000 076

001 003

002 323

003 020

004 076

005 025

006 323

007 020

010 041

011 256

012 017

013 061

014 032

015 000

016 333

017 020

020 017

021 320

022 333

023 021

024 275

025 310

026 055

027 167

030 300

031 351

032 013

033 000

Follow these steps to enter the bootstrap loader:

1) Turn the power switch on.

2) Raise and hold the STOP switch in the STOP position, then raise and re-

lease the RESET switch. Finally, release the STOP switch. This performs

a hard reset on the computer and sets all address lights to zero.

3) Put the first data byte in switches 7 through 0, then raise DEPOSIT.

- 19 -

4) Put the data for the next address in switches 7 through 0, then depress

DEPOSIT NEXT.

5) Repeat step 4 until all bytes have been entered.

6) Raise and release RESET to force all address lights back to zero.

7) Verify the data shown on lights D7 through D0 matches the data byte for

the current address. If the value is correct, go to step 9, otherwise

go to step 8.

8) Put the correct value in switches 7 through 0, then raise DEPOSIT.

9) Depress EXAMINE NEXT

10) Repeat steps 7 through 9 to validate entry of the entire program.

Once the bootstrap loader is entered and verified, we’re almost ready to load

the BASIC paper tape. But first, we must set the run address to zero and then

set the front panel sense switches to tell the checksum loader and BASIC the

type of serial port that is in use:

1) Set all address switches to zero.

2) Raise EXAMINE to set all address lights (and the 8080 program counter)

to zero.

3) Raise A11 and A10 to the up position. This tells the checksum loader

and BASIC that you are using a 2SIO serial board with one stop bit to

load BASIC and to use as your console.

Now we’re finally ready to actually load BASIC!

1) Depress RUN to run the bootstrap loader. If the loader was entered cor-

rectly, address lights A12, and A4-A0 should be on.

2) Transmit the paper tape image by using the “File->Send File” menu op-

tion in TeraTerm. Browse to and select the file “4K Basic Ver 3-2.tap”

which is located in the “Paper Tape and Cassette” folder inside the

“BASIC” folder. Be sure the “binary” checkbox at the bottom of the send

file dialog is checked when sending a paper tape file.

3) Loading BASIC will only take about five seconds at 9600 baud (instead

of seven minutes at 110 baud!). Once loaded, BASIC initializes and

prompts the user for memory size. The prompt may look a bit garbled as

shown:

MEMORY SIZã?

This occurs because 4K BASIC uses bit 7 to store additional informa-

tion. However, because teletypes ignored bit 7, this did not cause a

problem. We can duplicate this effect in TeraTerm by choosing “Setup-

>Serial Port” and setting the “Data” field to 7 bits, and setting the

“Parity” field to “Space.” (Note: These settings must be returned to

8N1 if you need to start over and send the paper tape file once again).

4) Turn on “Caps Lock” on the keyboard.

5) In response to the “MEMORY SIZE” prompt, key in 20000 and press return.

(You can simply press RETURN and let BASIC determine memory size as

long as you have a PROM installed. Otherwise, BASIC will loop forever

and clobber itself while it looks for the end of RAM!).

6) In response to the “TERMINAL WIDTH” prompt, press RETURN.

7) In response to the “WANT SIN?” prompt, key in “Y” and press return.

- 20 -

At this point, 4K BASIC is up and running! You can type an immediate command

like “PRINT 2+2” and press RETURN. BASIC will display the answer, 4. You can

also type in a program and run it. Note that in these early versions of BA-

SIC, the underscore character “_” is used as the delete key. The underscore

does not cause a visible delete or backspace. The underscore character is

echoed, but it’s up to you to figure out how many characters you have deleted

as you type underscores. Here is a simple program you can key in and “RUN”:

10 FOR I=1 TO 20

20 PRINT “LOOP”;I

30 NEXT I

Loading a BASIC Program from Paper Tape

4K BASIC does not have any sort of “load” command, instead, programs are

“typed” in by transmitting a paper tape which contains a listing of the pro-

gram. At 110 baud, BASIC can keep up with reception of the program. However,

at higher baud rates, BASIC needs a delay after each line is received so that

it can process and store the line of code before more data comes in. For a

fast paper tape reader, consecutive nulls (binary zeros) were often punched

after each line to provide this delay. The nulls were missed while BASIC pro-

cessed a line of code, then when receiving again, BASIC ignored the nulls un-

til valid data at the start of the next line was received.

Rather than inserting nulls after each line in the program source files, Ter-

aTerm can be configured to delay after each line of code to accomplish the

same effect. Go to the “Setup->Serial Port” menu in TeraTerm and enter “300”

in the “msec/line” field. This provides a 0.3 second delay after each line to

give BASIC time to process the line of code.

A number of BASIC programs compatible with 4K BASIC are present in the folder

“BASIC\BASIC programs\4K BASIC.” Follow these steps to try the programs:

1) Type “NEW” followed by RETURN to clear program memory.

2) Use the “File->Send File” menu option in TeraTerm to browse to and

transmit the BASIC program you want to load.

3) The program will display on the screen as BASIC reads it in. The file

transmit dialog box will close before the PC actually finishes trans-

mitting the program. This is normal.

4) Once the program is loaded, type “RUN” followed by RETURN to execute

the program.

5) Repeat steps 1-5 to try another program.

When you are finished, use the TeraTerm “Setup->Serial Port” menu to restore

8N1 and to set the transmit delay back to zero. This helps avoid problems and

confusion with the next exercise you may try!

More Information

Be sure to look at the 1975 BASIC manual (Altair Manuals\BASIC Manual 75.pdf)

for more information about 4K BASIC.

- 21 -

C. Loading and Using 8K BASIC from Cassette

In this demonstration, we will load 8K BASIC Version 4.0 from a cassette tape

file. The 88-ACR cassette interface for the Altair consisted of an audio mod-

ulator/demodulator board that connected to a standard cassette recorder and

to an 88-SIO serial interface board. The SIO board provided the data inter-

face with the Altair bus. The digital content present on the cassette tape

for loading BASIC was the same data and format as used on paper tape.

In this exercise, we will not use the cassette player and tape itself, but

instead send the data contained on the cassette through the same SIO board

and port addresses as used by the 88-ACR cassette interface (the Altair won’t

know the difference!) A separate serial port is used to connect to the opera-

tor’s terminal.

Note: If you have the optional Audio Cassette Interface for the Altair Clone,

this same demonstration is present in the Cassette Interface User’s Manual

using a real cassette and tape player!

Computer Configuration

Serial port 1 on the Altair Clone (the upper DB-25 connector) should be

configured as a 2SIO serial port at octal I/O address 20/21. This port

serves as the operator’s terminal. This is a standard Altair configura-

tion. This is also the default Altair Clone configuration for port 1.

The cassette data comes in on serial port 2 (the lower DB-25 connector)

which should be configured as an SIO board at octal I/O address 6/7. This

is the standard cassette configuration in the Altair. This is also the de-

fault Altair Clone configuration for port 2.

You can confirm or change the Clone’s serial port configuration if needed.

See “Serial Port Menu” in Part 2, “Configuration Monitor” of this manual.

The default baud rate for the cassette SIO port on the Clone is 9600 baud.

While this is much faster than the 300 baud at which the real cassette in-

terface operated, we recommend using 9600 baud for this demonstration.

Buffering in the PC’s serial port drivers and issues with some USB-to-

Serial adapters can make operation at 300 baud problematic.

Terminal Emulator Configuration

The TeraTerm terminal emulator is used to duplicate the functionality of

both the operator’s console and the cassette player. First, start an in-

stance of TeraTerm to use as the operator’s console. Then, start a second

instance of TeraTerm to use as the cassette player. You’ll probably re-

ceive a “Cannot Open Serial Port” error when you open the second TeraTerm

window. In the second window, go to the “Setup->Serial Port” menu and

choose the COM port that serial port 2 from the Clone (the cassette inter-

face) is connected to.

In the console TeraTerm window, choose “Setup->Serial Port” and set the

“Data” field to 7 bits, the “Parity” field to “Space” and verify the baud

rate is 9600. Also confirm that the “Transmit Delay” fields are both set

to zero.

In the cassette TeraTerm window, confirm serial settings of 9600 baud, 8

bits, no parity and one stop bit. Also confirm that the “Transmit Delay”

fields are both set to zero.

To load 8K BASIC, we must first enter a small program via the front panel

called a “bootstrap loader.” The job of the bootstrap loader is to receive a

second loader from the tape called the “checksum loader.” The checksum loader

is at the beginning of the BASIC tape. Once the checksum loader has been read

- 22 -

into memory, the checksum loader then reads in BASIC from the remainder of

the cassette tape.

The code for the bootstrap loader is provided by Altair in the BASIC manual.

Different versions of the bootstrap loader are required based on the version

of BASIC and the type of interface card being used to load BASIC. For this

demonstration, we need the bootstrap loader for the 88-ACR cassette interface

and for 8K BASIC Version 4.0. Following is the bootstrap loader code for this

combination of BASIC and serial port type:

Addr Data

---- ----

Addr Data

---- ----

Addr Data

---- ----

000 041

001 302

002 037

003 061

004 022

005 000

006 333

007 006

010 017

011 330

012 333

013 007

014 275

015 310

016 055

017 167

020 300

021 351

022 003

023 000

Follow these steps to enter the bootstrap loader:

1) Turn the power switch on.

2) Raise and hold the STOP switch in the STOP position, then raise and re-

lease the RESET switch. Finally, release the STOP switch. This performs

a hard reset on the computer and sets all address lights to zero.

3) Put the first data byte in switches 7 through 0, then raise DEPOSIT.

4) Put the data for the next address in switches 7 through 0, then depress

DEPOSIT NEXT.

5) Repeat step 4 until all bytes have been entered.

6) Raise and release RESET to force all address lights back to zero.

7) Verify the data shown on lights D7 through D0 matches the data byte for

the current address. If the value is correct, go to step 9, otherwise

go to step 8.

8) Put the correct value in switches 7 through 0, then raise DEPOSIT.

9) Depress EXAMINE NEXT

10) Repeat steps 7 through 9 to validate entry of the entire program.

Once the bootstrap loader is entered and verified, we’re almost ready to load

BASIC. But first, we must set the run address to zero and then set the front

panel sense switches to tell the checksum loader and BASIC the type of serial

ports in use for the console device and for the load device:

1) Set all address switches to zero.

2) Raise EXAMINE to set all address lights (and the 8080 program counter)

to zero.

3) Raise A12 to the up position. This tells the checksum loader and BASIC

that a 2SIO serial board with one stop bit is the console interface.

4) Raise A9 and A8 to the up position. This tells the checksum loader that

the cassette interface is being used to load BASIC.

Now we’re finally ready to actually load BASIC!

- 23 -

1) Depress RUN to run the bootstrap loader. If the loader was entered cor-

rectly, address lights A10-A9, and A4-A0 should be on.

2) Use the “File->Send File” menu option in the cassette TeraTerm window

to transmit the cassette tape image to the Altair. Browse to and select

the file “8K Basic Ver 4-0.tap” which is located in the “Paper Tape and

Cassette” folder inside the “BASIC” folder. Be sure the “binary” check-

box at the bottom of the send file dialog is checked.

3) Loading BASIC will only take about eight seconds at 9600 baud (instead

of about four minutes at 300 baud!). Once loaded, BASIC initializes and

prompts the user for memory size.

4) Turn on “Caps Lock” on the keyboard.

5) In response to the “MEMORY SIZE” prompt, press RETURN to let BASIC de-

termine the amount of RAM present.

6) In response to the “TERMINAL WIDTH” prompt, press RETURN.

7) In response to the “WANT SIN?” prompt, key in “Y” and press return.

At this point, 8K BASIC is up and running! You can type an immediate command

like “PRINT 2+2” and press RETURN. BASIC will display the answer, 4. You can

also type in a program and run it. Note that in these early versions of BA-

SIC, the underscore character “_” is used as the delete key. The underscore

does not cause a visible delete or backspace. The underscore character is

echoed, but it’s up to you to figure out how many characters you have deleted

as you type underscores. Here is a simple program you can key in and “RUN”:

10 FOR I=1 TO 20

20 PRINT “LOOP”;I

30 NEXT I

Loading a BASIC Program from Cassette Tape

In 8K BASIC, the “CLOAD” and “CSAVE” commands can be used to load and save

programs from cassette. The CSAVE command writes an image of the program as

it exists in RAM to the tape. Since the program in RAM is already pre-

processed and encoded to run, this format loads and saves more quickly than a

printable listing of the program. However, this means the CLOAD command can-

not be used to load a program in printable (ASCII) format – only programs

previously saved with a CSAVE command. Also, since “Extended BASIC” encodes

programs differently in memory than 8K BASIC, files saved to cassette are not

compatible between these two versions of BASIC.

The file “BASIC\BASIC Programs\8K BASIC\cassetteDemo.tap" is an image of a

cassette tape created by saving programs from 8K BASIC using the CSAVE com-

mand. The tape contains two BASIC games, hangman and lunar lander.

To load the hangman program type: CLOAD "H"

or...

To load the lunar lander program type: CLOAD "L"

After typing the desired load command and pressing return, use the “File-

>Send File" menu option in the cassette TeraTerm window to send the file

"cassetteDemo.tap" to the Altair. BASIC scans the data coming in from the

cassette looking for the one character file name specified in the CLOAD com-

mand ("H" or "L"), then loads that program.

You’ll find that even at 9600 baud, the CLOAD command can keep up without re-

quiring transmit delays in the file transfer. Since the program was saved to

- 24 -

tape as a RAM image of the program, BASIC does not have to encode the program

as it is received. Pretty impressive speed for an old computer and software!

Saving a BASIC Program to Cassette Tape

Programs can be added to an existing tape file, or written to a new file as

follows:

1) Use the "File->Log..." menu option in the cassette TeraTerm window to

specify a file to write as the cassette tape. Check the "Binary" check-

box. Check the "Append" check box if you want to add to an existing

cassette tape. Click "Save" to start the file save process.

2) Type CSAVE "x" in BASIC where x is a one character "file name" that is

different than any other file name on the tape.

3) After the CSAVE operation completes and BASIC displays "OK," click on

the TeraTerm:Log icon on the Windows taskbar to display the TeraTerm

Log dialog box. Choose "Close" to finish the file save operation.

Loading a BASIC Program through the Console

The majority of BASIC programs you’ll find are not in 8K compatible cassette

format, but instead, are provided as a simple ASCII listing of the program.

The same technique used to load programs through the console serial port in

4K BASIC can be used to load these programs into 8K BASIC. For more informa-

tion on why the following steps work, see “Loading a BASIC Program from Paper

Tape” in the 4K BASIC demonstration.

Choose the “Setup->Serial Port” menu option in the console TeraTerm window

and enter “300” in the “msec/line” field. This provides a 0.3 second delay

after each line to give BASIC time to process the line of code. (You may have

to increase the delay to 500 msec/line to load larger programs since the line

encoding process gets slower as the program size increases.)

Program files compatible with 8K BASIC are present in the “4K BASIC,” “8K BA-

SIC” and the “Games (Creative Comp)” folders inside the ““BASIC\BASIC pro-

grams” folder. Note, most of the programs in the Games folder will work in 8K

BASIC, but not all of them. The 72 character line length limit in 8K BASIC is

typically the culprit. Follow these steps to try the programs:

1) Type “NEW” followed by RETURN to clear program memory.

2) Use the “File->Send File” menu option in TeraTerm to browse to and

transmit the BASIC program you want to load.

3) The program will display on the screen as BASIC reads it in. The file

transmit dialog box will close before the PC actually finishes trans-

mitting the program. This is normal.

4) Once the program is loaded, type “RUN” followed by RETURN to execute

the program.

5) Repeat steps 1-5 to try another program.

When you are finished, use the TeraTerm “Setup->Serial Port” menu to restore

8N1 and to set the transmit delay back to zero. This helps avoid problems and

confusion with the next exercise you may try!

More Information

Be sure to look at the 1977 BASIC manual (Altair Manuals\BASIC Manual 77.pdf)

for more information about 8K BASIC.

- 25 -

D. Loading and Using Disk BASIC from Floppy Disk

In this demonstration, we will boot and use Altair Disk BASIC version 5 (spe-

cifically version 300-5-F).

Computer Configuration

Serial port 1 on the Altair Clone (the upper DB-25 connector) should be

configured as a 2SIO serial port at octal I/O address 20/21. This port

serves as the operator’s terminal. This is a standard Altair configura-

tion. This is also the default Altair Clone configuration for port 1. You

can confirm or change the Clone’s serial port configuration if needed. See

“Serial Port Menu” in Part 2, “Configuration Monitor” of this manual.

To boot a floppy disk, the “Disk Boot Loader” (DBL) PROM was typically in-

stalled in the Altair. Refer to the “PROM Menu” section in Part 2, “Con-

figuration Monitor” to see if this PROM is already installed in the Clone.

If not, follow the instructions to “Load New PROM Content” and install the

.hex file “ROMS\DBL.HEX” into one of the empty PROM slots.

Follow the “Insert Floppy” instructions in the “Floppy Disk Menu” section

of Part 2, “Configuration Monitor” to insert the floppy image “BA-

SIC\Floppy Disk\Games on 300-5-F.dsk”. Either load the floppy directly

into drive 0, or use the “Change Drive Assignment” menu option after up-

loading to assign the floppy to drive 0. Once you have uploaded the flop-

py, you do not need to repeat this step unless you over-write the floppy

with other content.

Follow these steps to boot Altair BASIC from floppy disk:

1) Turn the power switch on.

2) Raise and hold the STOP switch in the STOP position, then raise and re-

lease the RESET switch. Finally, release the STOP switch. This performs

a hard reset on the computer and sets all address lights to zero.

3) Set switches A15-A8 to the up position (one) and switches A7-A0 to the

down position (zero). This represents the start address of the Disk

Boot Loader (177400 octal or FF00 hex).

4) Raise the EXAMINE switch to load this address into the processor.

5) Set switches A15-A13 to the down position. This leaves the first four

switches (A15-A12) set to 0001. This tells BASIC the console terminal

is connected to a 2SIO board with one stop bit.

6) Depress the RUN switch to boot the Altair from the BASIC floppy.

7) In response to the “MEMORY SIZE” prompt, press RETURN to let BASIC de-

termine the amount of RAM present.

8) In response to the “LINEPRINTER” prompt, key in “O” (capital letter

“oh”) and press RETURN.

9) In response to “HIGHEST DISK NUMBER” key in “2” and press RETURN.

10) In response to “HOW MANY FILES” key in “4” and press RETURN.

11) In response to “HOW MANY RANDOM FILES” key in “4” and press RETURN.

At this point, Disk BASIC is up and running! You can type an immediate com-

mand like “PRINT 2+2” and press RETURN. BASIC will display the answer, 4. In

this version of BASIC, the backspace key performs the normal “destructive

backspace” to which you are accustomed.

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Loading a BASIC Program from Disk

Before a floppy disk can be used with BASIC, it must be mounted. Type “MOUNT

0” to tell BASIC to mount the floppy that is in drive zero. After the command

completes (it may take ten or more seconds to complete), type “FILES” to list

the files present on the disk.

You can load a program with the “LOAD” command, or load and run a program

with the “RUN” command. The file name specified for either command must be

contained in quotes and is case-sensitive. For example, to load the StarTrek

game, type the following:

LOAD “STARTREK”

and press RETURN. After the program loads, you can type “LIST” to look at the

program or “RUN” to execute the program.

Loading a BASIC Program through the Console

You can also load a BASIC program through the console in the same manner as

detailed in the 4K BASIC and 8K BASIC demonstrations. This allows you to load

new programs from a PC and then save the program to the floppy disk.

The “SAVE” command writes a program in memory to the floppy disk. For exam-

ple, to save a program in memory to the file name “NEWPROG,” type the follow-

ing:

SAVE “NEWPROG”

and press RETURN to write the program to the floppy disk.

If you have modified a floppy with new content and you want to archive the

floppy to your PC, follow the “Save Floppy Content to PC” instructions in the

“Floppy Disk Menu” section of Part 2, “Configuration Monitor” to write the

floppy image to a file on your PC.

More Information

Be sure to look at the 1977 BASIC manual (Altair Manuals\BASIC Manual 77.pdf)

for more information about all versions of Altair BASIC.

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E. Loading and Using Altair DOS

In this demonstration, we will boot and use Altair DOS version 1.0. Announced

in 1975, but not delivered until 1977, Altair DOS was never widely adopted.

By the time it was released, the much easier to use and more flexible CP/M

operating system was rapidly gaining popularity.