MPI_Floppy_Interfacing_Guide_Feb1980 MPI Floppy Interfacing Guide Feb1980
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MICRO PERIPHERALS INC. FLEXIBLE DISK DRIVE INTERFACING GUIDE REPRESENTED BY RSSDEIAIES 14431 MIRANDA ct LOS ALTOS HILLS CALIFORNIA 94022 (415)941-4133 PROPRIETARY NOTICE Information contained in this manual is copyrighted, and may not be duplicated in full or in part by any person without prior written approval from Micro Peripherals, Inc. (MP\) The purpose of this manual is to provide the user of MPI's Model 51/52 Flexible Disk Drives with adequately detailed documentation necessary for efficient installation, operation and interfacing for the equipment supplied. Every effort has been made to keep the information contained in this manual current and accurate as of the date of publication or reVISion. However, no guarantee is given or implied that the manual is error free, or that it is accurate with regard to any particular specification. Published February 1980 MICRO PERIPHERAlS INC. 9754 Deering Avenue Chatsworth, California 91311 (213) 709-4202 TWX: 910-494-1213 TABLE OF CONTENTS ..... Section Specifications. Section 2 Ins t a 11 at ion • • Page Section 3 Interfacing Requirements. Page 5 Section q Data Encoding and Recovery. Page 10 ii Page SECTION I SPEC I FI CAT I ONS 1.0 INTRODUCTION This section provides the mechanical and electrical specifications for the Model 51/52 Flexible Disk Drives. 1.1 SPECIFICATIONS The mechanical and electrical specifications for the Model 51/52 Flexible Disk Drives are given in Table 1-2. Data capacity for the Model 51/52 Flexible Disk Drives is given in Table 1-1. TABLE 1-1 DATA CAPACITY UNFORMATTED (K BYTES) PARAMETER Track Disk SINGLE DENSITY (FM) 51 52 3.13 125 3.13 250 DOUBLE D~NSITY (MFM. M FM) 51 52 6.25 6.25 250 500 SECTI ON 2 INSTALLATION 2.0 INTRODUCTION This section provides the information and procedures necessary for installing the Model 51/52 Flexible Disk Drives. 2.1 UNPACKING During unpacking, care must be exercised to ensure that all tools are nonmagnetic and do not inflict damage to the unit. As the unit is unpacked, inspect it for possible shipping damage. All claims for this type of damage should be filed promptly with the transporter involved. If a claim is filed for damages, save the original packing material. Most packing material may be reuseable if reasonable care is used in unpacking. Unpack the drive as follows: A. B. C. D. Eo F. G. Remove external packing material carefully. ~ Remove the drive from the container. Remove internal packing materials, following instructions provided on the package. Ensure that front access door opens and closes, and that the head load arm raises when door is opened. Ensure that bezel is secured. Ensure that drive hub manually rotates freely. Ensure that stepper motor/head carriage assembly is not binding at any point, by manually moving carriage back and forth. TABLE 1-2 MECHANICAL AND ELECTRICAL SPECIFICATIONS PARAMETER CHARACTERISTICS Media ANSI standard 5 1/4 inch diskette Number of Tracks 40/51 80/52 Track Density 48 TPI Rotational Speed 300 rpm.!. 1 1/2% Average Latency 100 msec Head loading time 35 msec 5 msec, track-to-track Access time Head settling time Head life 15 msec Recording method 20,000 hours 3 x 10 6 passes on a single track FM, MFM, M2FM Recording density 2938/5876 bpi max. Flux density 5876 fci max. Data-transfer rate 125K/250K bits/sec. Power-up Delay Height 0.5 sec 3.25 inches (8.255 cm) Width 5.75 inches (14.605 cm) Length 7.6 inches (19.30 cm) Weight 3.0 pounds (1.36 kg) Power +12 VDC Typical Power Dissipation +5 VDC.!. 5%, 0.4A, .1 V ripple 12W Operation Media life ! 5%, 0.8A (1.5A surge), .2 V ripple 6w Standby Operating Temperature 40°F to 115°F (4.4°c to 46:1°C) Non Operating Temperature -40°F to 160°F (-40°C to 71°C) Operating Humidity 20% to 80% (noncondensing) Non Operating Humidity 5% to 95% (noncondensing) Operating Altitude -500 ft to 10,000 ft (-152.4m to 3,048m) Non Operating Altitude -1000 ft to 50,000 ft (-304.8m to 15,240m) Vibration and Shock (Operating) MTBF 6 to 600 Hz, 0.5g MTTR 0.5 Hours 9,200 Hours 2 2.2 INSTALLATION Due to its small size and light weight, the Model 51/52 can be installed or mounted in any convenient location or position. However, the drive must be installed in a location that will prevent the I/O cable from exceeding 10 feet in length. Refer to Figure 2-1 for dimensions and mounting provisions. 2.3 HARDWARE The flexible disk drive is a precision device in which certain critical internal alignments must be maintained. Therefore, in keeping with rigid disk requirements, it is important that the mounting hardware does not introduce significant stress on the drive. Any mounting scheme in which the drive is part of the structural integrity of the enclosure is not permitted. Since the disk drive cannot be SUbjected to signiffcant stress when it is slide mounted, this type of mounting generally satisfies the foregoing requirements. Mounting schemes should allow for adjustable brackets or incorporate resilient members to accommodate tolerances. Mounting schemes involving more than two hard mounting points and a third point should be avoided. 2.4 DUST COVER Since the flexible disk drive is not provided with a dust cover, the design of an enclosure should incorporate a means to prevent direct ingress of loose items, e.g., dust, paper punch waste, etc. 2.5 COOLING Heat dissipation from a single disk drive is normally 12 watts (32 Btu/Hr). When the drive is mounted so that the components have access to free flow of air, normal convection cooling allows operation over the specified temperature range. When the drive is mounted in a confined environment, air flow may have to be provided to maintain specified air temperatures in the vicinity of the motors, PCBA, and the diskette. 2.6 INPUT/OUTPUT CABLE Refer to Table 2-1 for cable connector part number and attachment. The maximum cable length from connector to connector is 10 feet. All inputs and outputs are paired, one 1 ine for function, one for ground. Figure 3-9 provides information relative to the connector pin/signal assignments for the t/O cable. TABLE 2-1 RECOMMENDED CONNECTORS -PI CONNECTOR PIN TYPE OF CABLE MANUFACTURER Twisted Pa i r, 26 AMP Flat Cable 3M ··Scotchflex" 3 583717-S 3463-0001 CONTACT PIN 1-583616-1 N.A. Top View Bottom View 1.87 (4.74 cm) 1 .125 (.318 cm) 3.125 I ~ (7.94 cm) ~ \.:1;/ 1- l I ..... ,,- ". 5.87 (14.9 1 cm) o ... ..... 7cm) I ~ L J=.h .=\ 6-32 x .31 deep (4) mtg. holes Door Open Position 3.38 (8.59 '" n) L IP ~ t .06 (.15 :m) ::t1 ====- -11 / - • I~ Door Closed Position 5.75 (14.6 1 cm) yp Single Interface Connector (J 1) (.15 cm) ~ C8 DC Power Connector (J2) 6-32 thru mtg. h( es (2 plcs. each side) - .8n (2.22 cm) 1.87 (4.74 cm) 3;125 7.6 max (19 frr - NOTE: t Unless otherwise stated, dimensions are in inches. Tolerances: (.79 cm) Side View Figure 2-1 Outline and Mounting Dimensions .xxx . xx ±. 0.010 ±. 0.020 2.7 DC POWER DC power to the drive is via connector J2, which is located on the non-component side of the PCBA near the spindle motor. The drive uses +12V DC and +5V DC. Table 1-2. outl ines the voltage and current requirements. The connector is an AMP Mate-N-Lock Part No. 1-480424-0. SECTION 3 INTERFACING REQUIREMENTS 3.0 INTRODUCT ION This section contains the interfacing requirements between the host system and the Model 51/52 Flexible Disk Drive. Communication is established via two connectors. Connector Jl establishes a communication link for all input/ output signals. These signals are TTL compatible. Connector J2 provides DC power to the device. 3.1 INPUT LINES The input control lines have the following electrical specifications: A. B. True, Logical Zero False, Logical One 3.1.1 Line Termination = OV = to 0.4v (@ lin = 48 ma max). +2.5V to +5V (open collector @ lout = 250 ~a max). The signal interface used by the Model 51/52 is of the "bus" or "daisy-chain" type. Only one 51/52 unit is logically connected to the interface at any given time. All input signals are terminated directly by a 150 ohm or a 220/330 ohm resistor network. In a daisy-chain configuration, only the last device in the daisy chain should have the terminating network; while in a star configuration, every device should be terminated. 3. 1 .2 Programmable Shunt The main function of this device js to assign the proper address t6 the drive in a multidrive configuration. 1n addition, it also determines when the head load solenoid should be activated by using either position 1-14 (with Select) or 7-8 (with Motor On). If position 5-10 is left shorted, the drive is essentially always selected, but the activity light will not come on, and the solenoid will not be activated until the drive position is selected. The programmable shunt is AMP PIN 435704-6 (HPI PIN 1-79600-0o~). For convenience, the programmable shunt could be replaced by a dip switch, AMP PIN 435626-J• (MPI PIN 1-7960J-001). (If dip switch is used, maximum height is exceeded by ;150.) The seven lines channeled through the shunt are: a. b. c. d. e. f. g. Designator Tl T2 T3 T4 T5 T6 T7 Head Load w/Select Drive Select 1 Drive Select 2 Drive Select 3 MUX Drive Select 4 Head Load w/Motor On 5 Pins 1-14 2-13 3-12 4-11 5-10 6-9 7-8 3. 1 .3 Drive Select 1 to 4 The Drive Select lines provide a means of selecting and deselecting one of up to four disk drives. When the signal logic level is true, the disk drive electronics are activated, the head is loaded, and the ~rive is conditioned to respond to step or read/write commands. When the logic level is false, the input control lines and output status lines are disabled. A select line must remain stable in the true state until the execution of a step or read/write command is completed. After the desired device is selected, allow a 35 msec delay before initiating a read (see Figure 3-2) or write (see Figure 3-4). 3.1.4 Hotor On This input is provided to extend the life of the DC spindle motor. The motor should be turned off if no activity is required of the Hodel 51/52 after 10 revolutions of the diskette. A true level on this line turns on the drive motor. A minimum of 0.5 second is required before performing a read or write after a MOTOR ON command is transmitted to the device (see Figures 3-2 and 3-4) • 3.1 .5 Direction Select The direction of motion of the read/write head is defined by the state of this input line. A true level defines direction as "IN" (towards center of the disk); a false level defines the direction as "OUT" (see Figure 3-1). 3. 1 .6 Together with the direction line, a single pulse on this input will move the read/~rite head one track in or out, dependent on the state of the direction line. The motion of the head is initiated on the trailing edge of the step pulse. A minimum of 0.2 ~s pulse width at a maximum frequency of 200 Hz should be maintained to assure step integrity (see Figure 3-1). 3.107 Write Gate When true, this input line permits writing of data. When false, it permits transmitting data to the controller. Write gate must be high for 10 ms minimum after tornirig off DC power (see Figure 3-6). Allow a minimum of I msec after dropping write gate before expecting val id Read Data (see Figures 3-2 and 3-6). During this 1 msec period, Side Select (see paragraph 3.1.9) must remain stable. 3. 1.8 Write Data This input, in conjunction with the write gate input, provides data to be written on the diskette. The frequency of the write oscillator shoul~be held within 0.1% with a pulse width of a minimum of 0.2 ~sec and maximum of 3.5 ~sec. The frequency is dependent upon the encoding scheme used and the density option exercised (see Figures 3-4 and 3-5). It is recommended that the first leading edge of Write Data occurs no sooner than 4 ~sec and no later than 8~sec after leading edge of Write Gate. The same recommendation exists for the last Write Data and trailing edge of Write Gate. 6 3. 1.9 Side Select This input is used to select either the upper. or lower head. A true level selects the upper head. a false level selects the lower head. A 35 ~sec delay should be allow.ed for the read amp to recover after a head select event occurs. Only then wi.ll valid data be present. (For Model 51, this line should always be high.) 3.1.10 In Use (optional fe~ture) This line is connected to a driver which could be used for an indicator light or a solenoid for locking the drive door. 3.2 OUTPUT LINES with an open-collector output stage at logical zero with maximum voltage the output Is at a logical one, the of 250 ~a. The control output signals are driven capable of sinking a maximum of 48 ma of 0.4v measured at the driver. When collector cutoff current is a maximum 3.2. 1 Track 00 This output, when true, indicates that the read/write head(s) are located at Track 00. 3.2.2 Index/SeCtor This output, when true, Indicates that an index or sector hole in the diskette is present at the ·index sensor (see Figure 3-7 and 3-8). 3.2.3 Write Protect This output, when true, indicates that a write protected diskette is installed in the drive. When an unprotected diskette Is installed, this output is false. When a protected diskette is installed, the write and erase logic on the PCBA is disabled. By making a small modification to the PCBA and using only protected diskettes, this output can be used as a Diskette [nstalled Indicator. 3.2.4 Read Data This output represents digitized data as detected by the drive electronfcs. Information transmitted will be in the encoding scheme used. Pulse width of both clock and data bits will be I usec + 350 nsec. Maximum bit shift from nominal for various encoding schemes is given in table 3-1 (see Figure 3-3). TABLE 3-1 BIT SHIFT FM MFM M2FM ::.7 00 +400 .!.7 00 .!.700 .!.475 Maximum bit shift (ns) clock data - 7 .!.7 00 Drive Select Motor ~--------~,------------Out Direction l--.-J In On -----,L_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Drive Select -II--O.l.,min.---! to.1.,min. L 0.3,1ls min. Step ---' Step 0.2,1.ts min. ------,suul~ 0.2., min. ----I I--- --J L . 1S--- Write Gate Valid Read Data 5msmm. :P.:.min. Figure 3-1 Track Access Timing Figure 3-2 Read Initiate Timing Motor On - - - - , " '_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Drive Select I~----------l-----------J-35 ms min._ Read Data Step A I A I A 1.------------ -----1---... I ---J A 1--20 m, min. i--. 0.5 sec min. - A - Leading Edge of Bit May Be ± 700 ns From its Nominal Position B - Leading Edge of Bit May Be ± 400 ns From its Nominal Position Write Gate ---l..--J 1-1 --1 Figure 3-3 Read Signal Timing Write Data !-s.OO,llS max. ----------~U1fUl~---- Figure 3-4 Write Initiate Timing --.J --1 DC Power r100m,min. Write Data ---,~~------------- Motor On (FM) --l 1-1_..:O::.2:::.':.:m:.::i:.::n·:......·-II_ _..:8::.OO:::·::'_-l1 ±. 40 ns 3.5,us max. 4.00., ±. 20 ns I-- Drive Select Figure 3-5 Write Data Timing Valid Trk. 00 and Wrt. Prot. Output Valid Index! Sector Output ~0.5secmin. ----t-+---, I--- O.5,1ls max. u Direction ~ U 200 ms ± 3.0 ms - - Step ~~~lJ 8.us max. I Write Gate -10 ms min. ~ --I Figure 3-7 Index Sector Timing (soft sector) ~..;....----- Write Data Valid Read Data I-- 20 m' min.~ ---++-----~~ l--ru-1--1 msec _____ 0.-53!cm~~~~ Figure 3-6 General Control and Data Timing Requirements (Head Load Solenoid is Activated with Drive Select) ±.19ms ±.10ms Figure 3-8 Index Sector Timing (hard sector) 8 J1 2 4 6 8 10 12 14 16 51/52 18 20 22 24 26 28 30 32 34 SPARE IN USE* DRIVE SELECT 4 INDEX/SECTOR DRIVE SELECT 1 DRIVE SELECT 2 DRIVE SELECT 3 MOTOR ON CONTROLLER DIRECTION STEP WRITE DATA WRITE GATE TRACK 00 WRITE PROTECT READ DATA SIDE SELECT RESERVED ODD PINS RETURN (DC GROUND) POWER J2 1 51/52 2 3 4 +12V 12V RETURN CONTROLLER POWER SUPPLY 5V RETURN +5V *IN USE may be configured as Door Lock or Activity Light. Figure 3-9 Interface Signals - 51/52 Pin Pin Pin Pin 1 2 3 4 +12V DC 12V Return 5V Return +5V DC BOARD THICKNESS .06.2! .007 Figure 3-11 J1 Connector Dimensions Figure 3-10 DC Power Connector, J2 9 3.3 CONNECTOR J2 The DC power connector is located on the non-component side of the printed circuit board. The recommended mating connector is AMP PIN 1-480424-0 using AMP pins PIN 60619-1 (see Figure 3-10). 3.4 CONNECTOR Jl Connection to Jl is through a 34-pin PCBA edge connector. Even numbered pins are located on the component side while odd numbered pins are located on the solder side. A key slot is provided between pins 4 and 6. The recommended connector is 3M Scotchflex PIN 3463-001, or AMP PIN 583717-5 using AMP contacts PIN 1-583616-1 (see figure 3-11). SECTION 4 DATA ENCODING AND RECOVERY 4.0 INTRODUCTION This section provides applications information relevant to the recording and recovery of data with the Model 51/52 Flexible Disk Drives. 4.1 ENCODING METHODS The three most common methods for encoding data are described in the following paragraphs. Table 4-1 shows a comparison of these encoding techniques. 4. 1 • 1 FM FM (frequency modulation) encoding has the following rules. A. B. A data bit, if it is a "1", occurs at the center of the bit cell. A clock bit occurs at the start of the bit cell. 1 o o o 1 o 1 1 BIT CELL = 8MS Figure 4-1 4.1.2 FM Encoding MFM MFM (modified FM) encoding has the following rules: A. A data bit, if it is a "1", occurs at the center of the bit cell. A clock bit occurs at the start of the bit cell, but only if no data B. bit occured in the previous bit cell and no data bit will occur in the current bit cell •. 10 - - - _... - - - - - - - - - - - - - I-- -I .. 6J..Ls U 1 ~8J..L5-1 4J..LS--I 0 I I 0 U Lr U U U 1 0 1 0 1 I BIT CELL = 4J..L5 Figure 4·2 MFM Encoding 4.1.3 M2FM M2FM (modified MFM) encoding has the following rules: A. B. A data bit, if it is a "1", occurs A clock bit occurs at the start of a data bit nor a clock bit occured data bit will occur in the current /--6J..L5 LJ I -I" 0 0 8J..L5 - - -..- U-------flU U. 1 ~14J..LS~ -I" 10J..L5 at the center of the bit cell. the bit cell, but only if neither in the previous bit cell and no bit cell. 0 I 1 0 I if 1 1 I BIT CELL = 4J..L5 Figure 4·3 M2 FM Encoding 4.2 DATA RECOVERY Data recovery refers to the retrieving of data off of the flexible diskette. following paragraphs describe the problems associated with data recovery and methods to ensure data reliability. 4.2. I The Bit Shift Bit shift refers to the displacement of a bit, as detected by the drive, from its nominal position. The causes of bit shift are manifold -- R/W head resolution, media resolution, diskette speed variation, signal-to-noise ratio of read head output. Any data separation technique used must have a tead window of at least 1500 ns to handle this bit shift. 4.2.2 Write Precompensation Certain data patterns cause more bit shift than other patterns. This bit shift is predictable and can thus be partially conpensated for. For example, if it is known that a bit will be shifted by 500 ns when it is read back, then the· bit 11 can be deliberately written 200 ns early. This would give a bit shift of about 350 ns when it is read back. This method of reducing bit shift is called write precompensation. Bit shift is greater on the inner tracks of the diskette than on the outer tracks, making write precompensation necessary only on the inner tracks. Write precomp of 250 to 300 ns should be used on tracks 18 through 39. If due to controller limitations, write precomp must be used on all tracks, then 125 to 150 ns should be used. Table 4-1 shows which encoding methods re'quire; the use of write precompensation. 4.2.3 Data Separation Data separation refers to the separating of the composite data coming from the drive into separate clock and separate data bits. For FM recording, a one-shot data separator is quite sufficient. For double density recording, a phase-lock oscillator (PLO) data separator should be used. There is another method of data separation, the digital counter method. This method is a very poor approxi,mation of a PLO. It has a theoretical read window of only 1000 ns which, as per paragraph 4.2.1, is not sufficient to handle bit shift. In MFM recording, data bits and clock bits are subject to the same amount of bit shift. A PLO separator with a 50% data window and a 50% clock window should be used. In M2FM recording, data bits are subject to more bit shift than clock bits. A PLO separator with a 60% data window and a 40% clock window should be used for best data reliability. It should be noted that the +700 ns bit shift is meaningful only when associated wi§h an error rate. The Model 51/92 drives have error rates of 1 error in 10 bits read. Thus, for every 10 bits, there will be no more than 1 bit shifted more than ~700 ns. 4.3 TRACK FORMAT When determining the track format to be used, the following timing restraints should be considered (see Figure 4-4). 4.3.1 Postamble The postamble period must be at least 3 ms to allow for spindle speed variation of +J-!%. 4.3.2 Data Gap The data gap period must be at least 1 ms to allow for tunnel erase turn off time. 12 TABLE 4-1 COMPARISON OF ENCODING TECHNIQUES Encoding Technique Bit Cell Time Possible pulse spacing FM 8 ,us 4 ',IJ s 8us Frequency components of read signal 125 KHz 62.5 KHz Encoder complexity Write precompensation needed Data separator recommended Data separator complexity Simple No One-shot Simple MFM 4 .us 4 .u s 6 ,us 8 .us 125 KHz 93.75 KHz 62.5 KHz Moderate Yes PLO(50-50 window) Moderate M2FM 4 ~S 4 )JS 6 )JS 8 IJS 10 .us 125 KHz 93.75 KHz 62.5 KHz 50 KHz Moderate Yes PLo(60-40 window) Moderate u~------------~$~~-------INDEX TRACK B E D - ID Gap E - Data Record F - Data Gap A - Postamble B - Preamble C -ID Record Figure 4-4 Typical Track Format 13 "
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