Wang 640 User manual

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-·WANG·
'
FLEXIBLE
DISK DRIVE
640
749
2240
Models:
2242
2243
Customer Engineering
Product Maintenance Manual
3102
729-0134-A

PREFACE
This publication is "l combined reprint of 729-0134 and 729-0135 for ease
of handling and stockine.
The purpose of this manual is to provide the Wang-trained Customer
Engineer (CE) with instructions to operate, troubleshoot and repair the Wang
Flexible Disk Drives.
Second Edition (February, 1984)
This edition is a reprint of and obsoletes 729-0134 and 729-0135. The
material in this document may only be used for the purpose stated in the
Preface. Updates and/or changes to this document will be published as
Publication Update Bulletins (PUBs) or subsequent editions.
This document is the property of Wang Laboratories, Inc. All information
contained herein is considered company proprietary, and its use is restricted
solely for the purpose of assisting the Wang-trained CE in servicing this Wang
product. Reproduction of all or any part of this document is prohibited
without the prior consent of Wang Laboratories, Inc.
©Copyright WANG Labs., Inc. 1984
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SERVICE BULLETIN NO. 46
EDITED BY PRODUCT SERVICE DEPT.
MODEL 640/740/2240 DUAL REMOVADLE
~ FLEXIBLE DISK DRIVE
.NOTICE:
This document is the"property of Wang Laboratories, Inc.
Information contained herein is considered company propri·
etary information and its use is restricted solely to the
purpose of assisting you in servicing Wang products. Aepro·
duction of all or any part of this document is prohibited
without the consent of Wang Laboratories.
( G)LABORATORIES, INC.
WAN~ 836 NORTH STREET. TEWKSBURY, MASSACHUSETTS 01876. TEL [phone], TWX 710 343-67119, TELEX 94- 1•21
Printed in U.S.A.
13·210

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4.
5.
TABLE OF CONTENTS
DESCRIPTION
1.1 General
1.2 Special Features
1.3 Hardware Nomenclature
INSTALLATION
OPERATION
3.1 Indicator Lights and Switches
3.2 Loading and Handling of Disk Cartridges
3.3 Disk Formatting
3.4 Model 740 Operation
3.5 Model 640 Operation
3.6 Model 2240 Operation
DIAGNOSTICS
4.1 Model 740 Diagnostic
4.2 Model 640 Diagnostics
4.3 Model 2240 Diagnostics
MAINTENANCE
5.1 Head Radial Alignment Check
5.2 Head Radial Alignment Procedure
5.3 Index and Sector Sensing Components
5.4 Carriage Stop Adjustment Procedure
5.5 Track 00 Switch Assembly
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3
4
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16
19
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20
22
23
25
26
27
27
30
33
35
38
40
42
45
46
APPENDIX A - 640 Beginning and Ending Track Addresses 48
APPENDIX B - 740 Beginning and Ending Track Addresses 50
APPENDIX C - 2240 Beginning and Enuing Track Addresses 52
APPENDIX D- Conversion from 640/740 to 2240 54
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1. DESCRIPTION
1.1 GENERAL
The Model 40 is a compact, direct access, removable disk unit made
up of two MemorexR 651 Disk Drives and a Wang Controller.
The controller for both drives is located behind the control panel
and consists of the following printed circuit boards:
1)
352 regulator
2) 6296
micro processor
3) *6297
micro processor
4)
6298
ROM
5) 6190
motherboard
6) 6391 power
supply
7)
6392
front panel
8)
6395
interface
9) 6399
disk control
*Per ECN #4074, the 640/2240 use a 6297-1 and the 740 uses a 6297-2.
The 651 drives are placed on either side of the controller and are Leferred
to as Left and Right. The left and right drives utilize FD/IV Flexible
Disk Cartridges each having a capacity of up to 262,144 bytes producing
a unit with a maximum of 524,288 bytes. The disk cartridges are inter-
changeable from one drive to another.
The Model 40 can replace the 710-1 Disk Drive; all adriressing and
read/write commands are identical with a few exceptions.
. R
Registered Trademark, Memorex Corporation
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1.2 SPECIAL FEATURES
Tlw Mo,kl 40 cnntaiils the following design features:
1) Compact: Allows easy exchange of disk drives •
..::) Compatihilitv: Permits the disk cartridges to be swapped between
drives and units.
3) lnt0rlncks: Contains interlocks which prevent damage to a disk
cartridge during loading or unloading.
4) Write Protect: Logic is provided to disable the write circuits
should the user wish to protect data recorded on the disk.
5) Byte addressing and multiple byte transfer to make it com~·:.itible
with 710 DMS's (740 only).
6) Cyclic Redundancy Check: A built-in check to insure tha~ data is
read corrl?ctly.
1. 3
1. 3.1
HARDWARE NOMENCLATURE
R
Memorex Portion
The Recd, Write, Safety and Control Logic are the interface electronics
between the Wang controller and the 651 drive (shown in Figure 1).
The electronic circuits are packaged on one PC board and contain:
1) Sector/Index Detector Circuits
2) Track Position Actuator Driver
3) Head Load Actuator Driver
4) Read/Write Amplifier and Transition Detector
5) Data/Clock Separation Circuits
6) Safety Sensing Circuits
RRegiPtered Trademark, Memorex Corporation
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FIGURE 1 INTERFACE ELECTRONICS
ln Figure 2 the track positioning actuator and lead screw positions
the Read/WritL' head to the desired track on the disk. The head load
actuator loads tlw disk against the Re.1d/Write head and data may then
be recorded or read from the disk.
The disk drive motor rotates the spindle at 375 RPM through a belt-
drive system. 50 or 60 Hz power is nccomodated by means of a stepped
pulley. /\ registration huh, centered on the face of the spindle, positions
the disk. A clamp (Lhat moves in conjuncl.i.on with the insertion door)
fixes the disk to Lhe registration hub .
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FIGURE 2
The Read/Write head is mounted on a carriage that is moved by the lead
screw. Ac:: shown in Figure 3, head load is achieved when the disk is
lightly loaded against the rigidly mounted head by energizing a solenoid.
This releases the bail from the spring-loaded carriage load arm and causes
the load arm pad to press against the head. ~eenergizing the solenoid
causes the retracting bail to lift the load pud from the disk thereby
unloading the disk.
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WHEN SOLENOID IS
DEENERGIZED. BAIL
RETRACTS AND PULLS
PAD AWAY FROM DISC
LOAD SPRING
CARRIAGE
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1.3.2 Wang Portion
SOLENOID
(ENERGIZED
FIGURE ~
• BAIL
DISC
Figure 4 is a top view of the Model 40. Facing the unit, the component
side of the PC boards is to the left except for the 352 regulator board
which faces to the right.
Figure 5 shows the PROM layout and part numbers for the various
units and capacities. When changing the storage capacity of a unit,
the only change that has to be made is the change of PROMs.
NOTE:
Figure 5 illustrates PROM loading only and not
conversion procedures from 640, 740, or 2240.
See Appendix Dfor conversion procedures .
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'Tl N
CXl
G">
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c:
0
:;:o
z
rTJ
t-l
+:>
•
651 DISK DRIVE
r----------------------------------------,
6390 MOTHERBOARD
()
0
~
0
z
tr1
z
t-l
639 5
6296
6297
6298
6399
r---- -- -,
"' I
~·
I-' I
I
"ti
I
0
~·
~
Ul I
C: I
~ L---,
l' I
~ I
r·--' I
---- If"---- I
: I J52 I
L- - - - - - - - - - - - - - - - - - - - __ - - - - - - - - - --' L ------- ---- - - - - - - J
l
651 DISK DRIVE
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640-1
640-2
740-1
740-2
2240-1
2240-2
J.l
L3
L4
J.5
L7
378-0227 378-0229R2 378-0228
378-0231 378-0233R2 378-0232
378-02181\~
:ns-0214 378-0216 378-0219R2 378-0215
378-0224R2 378-0220 378-0222 378-0225R2 378-0221
378-0235 378-0237Rl 378-0236
378-0239 378-0241R1 378-0240
8'B8lJE'BlJB
·ra ·~ ·~ ·~ rn ·~ ·ra ·~ ,~
·~ m ~ ·~ ·~ m ·[ill ·~ ·~ ·~
·~ ·~ ·rn ·rn ·~ ·~ ·rn ·rn ·~ ,rn ,~
FIGURE 5 PROM LOADING
Voltage Checks -352 Regulator
L8
378-0230R2
378-0234R2
378-02l 7Rl
378-·0223Rl
378-0238Rl
378-0242Rl
There are four voltages that should be checked, three being adjust-
able on the 352 regulator board. Measure all voltages with respect to
+OV on pin C or 3 of the 352 card,
VOLTAGE
POT
352 PIN NO.
1.
+5
R3 (Top right)
B or 2
2. +24 RlO(Top
left)
H
or
7
3. -13.5
Rl3(Bottom right)
A or
1
The fourth voltage is -9.5V which should be measured on pin 24 of
a PROM on the 6298.
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l, 3, 3 FD 'I\' f'lcxiblL' Disk Cartridge
1)
General (See Figure 6)
The Model 40 can write and read disks interchangeably from unit to
unit. The FD/JV Flexible Disk Cartridges used in the Model 40 are flat
disks composed of polyester substrate coated with a magnetic oxide and
are approximately 7 1/2" (19,05 cm) in diameter, For protection during
handling, operation, storage and mailing, the coated disks are encased
in a flexible vinyl envelope, eight inches square by one sixteenth inch
thick, which is sealed around the edges of the disk and lined with a
self-cleaning wiper. An oval slot in the envelope permits the Read/Write
head to access the d'sk for recording, Only one side of the cartridge
is used for recording,
OPENING FOR INDEX/SECTOR SENSING
KEYING NOTCH
WRITE PROTrcT TAB
PROTECTIVE
ENVELOPE\
~------------ ~-J--- I --p~~~~~~
~\ --0\
DISC
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FIGURE 6
FD/IV FLEXIBLE DISK CARTRIDGE
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ADHESIVE BACKING
READ/WRITE
HEAD ACCESS
SLOT
OPENING FOR
DRIVING HUB
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Formatting and writing on the disk can be inhibited by sliding a
fitted one inch by three fourths inch adhesive-backed write protect tab
into the keying notch of the vinyl envelope containing the disk.
When this removable plastic tab is in position and the disk is inserted
in the 651 drive, the raised portion of the tab pushes the actuator which
closes the write protect switch. · Once the switch is OFF (closed), the
file is protected. The full Read/Write capabilities can be restored
by physically removing the write protect tab.
2) Design and Utilization (See Figure 7)
There is only one recordable surface on each disk platter. The
proper surface is accessed when the platter is loaded into the disk
drive correctly.
Each surface of a disk contains 32 or 64 tracks depending on the
capacity of the unit. The tracks are numbered from the outside
inward starting with track O. Each track has a capacity of 4096
bytes. The table below summarizes tracks and total bytes •
MODEL
DISK
TRACKS
I TOTAL
TRACKS TOTAL BYTES
40-1
LEFT
32
64 262,144
RIGHT 32
40-2
LEFT
64 128
524,288
RIGHT 64
In the 740-1 unit, the addresses begin at track 0 of the left disk
until track 32 is reached, then they proceed to track 0 of the
right side.
In the 740-2 unit, the addresses begin at track 0 of the left disk
until track 31 is reached, then they proceed to track 0 of the
right disk. When track 31 of the right disk is filled, track 32
of the left disk is used until track 63 is encountered. The
addresses continue to track 32 of the right disk until track 63
is reached.
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DIRECTION
OF
ROTATION
0
3
SECTOR fJ
E TRA TIMING MARK
11
8
0
TRACK 63
FIGURE 7
DISK DESIGN AND UTILIZATION
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The 640 addresses begin orr the left disk and continue to the right
disk regardless of capacity •
The 2240 addresses are identical on both the left and right disks
regardless of capacity.
Each tra.;k ls divided into 16 sectors each containing 256 bytes.
Each sector is found by the unit using the timing marks as guides.
Every other timing mark constitutes a sector.
3) Cyclic Redundancy Check
4)
When data is recorded on the disk, two additional bytes are auto-
matically written by the controller at the end of each sector. On
a READ command, these bytes are transferred into the controller and
verify the fact that a correct READ took pla~e. This iR r~!!~~ a
Cyclic Redundancy Check (CRC).
How Data Is Written On A Disk
The Model 40 Wrices and Reads 256 bytes at one time. The 640 and
2240 addresses are entire sectors. The 740 is capable of writing
and reading the following number of bytes: 1, 8, 16, 32, 64, 128,
and 256. When using a 740, special attention must be paid to
transferring data efficiently.
In a 700/740 system, when a WRITE command is executed, the controller
writes 256 bytes, starting at the beginning of a sector, despite the
amount of bytes specified in the WRITE command and address issued by
the operator. For an operator to WRITE data most efficiently, the
operator should use WRITE 256 commands at an address which is a
multiple of 256. The following examples explain what happens when
a WRITE command is issued, and why a WRITE 256 at a sector address
is fastest •
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Example 1: WRITE 128 at Address 520
511 512
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CRC
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:s20
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647:
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,...,_ PORTION WRITTEN --..1
767 768
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CRC
(a) First, the system determines on what track and in what sector the
starting address is located and moves the READ/WRITE head to the
beginning of that sector.
(b) The READ/WRITE head then reads the entire sector, byte for byte,
into a buffer of 256 bytes. In the buffer, the bytes are manipulated
and the specified bytes (i.e., 520-647) are stored with the other
bytes remaining unchanged.
(c) The buffer is then written into sector 2.
(d) The reason the entire sector is read into the buffer is due to the
CRC. The CRC is calculated only for each sector and only when the
sector is written. Therefore, to have an up-to-date CRC, the CRC
must be recalculated each time any of the bytes in the sector are
changed. By reading the entire sector into the buffer, and then
rewriting it back onto the disk, the controller, in effect, is
writing the entire sector from scratch and calculates the new CRC.
There is no way for the controller to update a CRC for only a
portion of a sector without the controller rewriting the entire
sector.
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Example 2: WRITE 128 at Addr~ss 650
SECTOR
2
SECTOR
3
' '
511 512 ' I
' I
: 650
767
768
777: 1023 1024
'
_l l
A A
CRC
I._ PORTION WRITTEN -I
CRC
The procedure described for example 1 is identical for example 2,
except two sectors (2 and 3) are read into a buffer of 512 bytes. The
WRITE command involves bytes which overlap from one sector to the next.
Therefore, each sector CRC must be updated,
Example 3: WRITE 256 at Address 512
511 I512
------ ENTIRE SECTOR IS WRITTEN
The procedure is not the same in this example as it was in examples
1 and 2, The READ before WRITE is eliminated. The information written
goes directly from the buffer onto the disk because address 512 is a
multiple of 256. Therefore, the CRC can be calculated as the sector is
written the first time the sector passes under the READ/WRITE head•
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In examples 1 and 2 the sector had to pass under the READ/WRITE
head twice; once in order to read the sector into the buffer (first
rotation) and once to write it back onto the disk (second rotation).
A WRITE 256 at a sector address (multiple of 256) is the most efficient
means of writing data, as no extra rotations of the disk are required.
2. MODEL 40 INSTALLATION
The Model 40 is shipped in one box with two disk packs included.
Remove the unit from its box and remove the six screws holding the cover
in place; remove the cover. Next remove the six screws holding the
front panels in place; slide the front panel to the right and pull out.
CAUTION:
Do not open the drive doors to remove the front
panel. Damage to the head load bails may result.
When removing the front panel, insure that the control panel does nJt
fall forward, for it is modular and held in place by the front panel.
Disconnect the two ribbon cable connectors, one of which plugs into the
controller motherboard, the other into the front control panel; remove
the control panel. This will give easy access to the right drivP PCB
test points. At this point, remove the two plexiglass covers pru~ecting
the drive mechanics by pulling them forward. Now remove the tape restrain-
ing the head load bail of each drive, being careful not to disloca:~
the bail.
NOTE:
The disk cartridges must be installed to perform
the checks (tolerances). See Section 3.2.
There are two adjustments that must be checked before operating the
Model 40. First, the gap between t~e actuator bail and the actuator:
solenoid, and second, the gap between the actuator bail and the load·
arm tab. To check these adjust~ents, the left drive must be removed
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because the areas to be checked are inaccessible with the drive in the
unit, The left drive is held in place by four 3/8" bolts on the bottom
of the unit, Removal of the drive can he accomplished by sliding the
unit over the edge of the surface on which it is setting to allow access
to the bolts,
A gap between the actuator bail and the actuator solenoid should
be .030'' (,076 cm) measured at ,point A in Figure 8 (this can be done
with power off), Should this need adjustment, it is accomplished by
forming the tab D shown in Figure 8. By moving this tab away from the
solenoid bracket in direction F, the bail is moved closer to the solenoid
likewise by moving it closer to the solenoid bracket in direction E, the
bail is moved away from the solenoid,
FIGURE 8
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