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HEWLETT-PACKARD
liP 7936 AND HP 7937 DISC DRIVES
HARDWARE SUPPORT MANUAL
CERTIFICATION
Products, materials, parts, and services furnished on this order
have been provided in accordance with all applicable Hewlett-
Packard specifications. Actual inspection and test data per-
taining to this order is on file and available for examination.
Hewlett-Packard's calibration measurements are traceable to
the National Bureau of Standards to the extent allowed by the
Burea u 's calibration facilities.
The Hewlett-Packard Quality Program satisfies the require-
ments of FAR 52.246-15.
HP 7936 and HP 7937 Disc Drives
Hardware Support Manual
Manual part number: 07937-90903
Microfiche part no. 07937-90803
Printed: JANUARY 1987 Edition 1
Printed in U.s.A. E0187
MODELS COVERED
This manual covers the following models: HP 7936H, 7937H,
7936XP, 7937XP.
OPTIONS COVERED
In addition to the standard model, this manual covers the
following options: 015, 017.
r/;O- HEWLETT
a:~ PACKARD
HEWLETT-PACKARD
P.O. Box 39, Boise, Idaho 83707-0039
Notice
The information contained in this document is subject to change without notice.
HEWLETT-PACKARD MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS
MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. HEWLETT-PACKARD shall
not be liable for errors contained herein or for incidental or consequential damages in connection with the
furnishing, performance or use of this material.
HEWLETT-PACKARD assumes no responsibility for the use or reliability of its software on equipment
that is not furnished by HEWLETT-PACKARD.
This document contains proprietary information, which is protected by copyright. All rights are reserved.
No part of this document may be photocopied, reproduced or translated to another language without the
prior written consent of HEWLETT-PACKARD Company.
Copyright @ 1987 by HEWLETT-PACKARD
FOR U.S.A. ONLY
The Federal Communications Commission (in 47 CFR 15.818) has specified that
the following notice be brought to the attention of the users of this product.
FEDERAL COMMUNICATIONS COMMISSION
RADIO FREQUENCY INTERFERENCE
STATEMENT
Warning: This equipment generates, uses, and can radiate radio frequency energy and if not instal-
led and used in accordance with the instructions manual, may cause interference to radio com-
munications. It has been tested and found to comply with the limits for Class A computing devices
pursuant to Subpart J of Part 15 of FCC Rules, which are designed to provide reasonable protec-
tion against such interference when operated in a commercial environment. Operation of this
equipment in a residential area is likely to cause interference in which case the user at his own ex-
pense will be required to take whatever measures may be required to correct the interference.
2
Printing History
New editions are complete revisions of the manual. Update packages, which are issued between editions,
contain additional and replacement pages to be merged into the manual by the customer. The dates on the
title page change only when a new edition or a new update is published. No information is incorporated
into a reprinting unless it appears as a prior update; the edition does not change when an update is
incorpora ted.
A software code may be printed before the date; this indicates the version level of the software product at
the time the manual or update was issued. Many product updates and fixes do not require manual changes
and, conversely, manual corrections may be done without accompanying product changes. Therefore, do
not expect a one-to-one correspondence between product updates and manual updates.
Edition 1..................................................... JANUARY 1987
Herstellerbescheinigung
Hiermit wird bescheinigt, daB das Gerat/System HP 7936/7937 in Obereinstimmung mit den Bestimmungen
von Postverfiigung 1046/84 funkentstort ist.
Der Deutschen Bundespost wurde das Inverkehrbringen dieses Gerates/Systems angezeigt und die
Berechtigung zur Oberpriifung der Serie auf Einhaltung der Bestimmungen eingeraumt.
Manufacturer's Declaration
This is to certify that the product(s) HP 7936/7937 is in accordance with the Radio Interference
Requirements of Directive FTZ 1046/1984. The German Bundespost was notified that this equipment was
put into circulation; the right to check the series for compliance with the requirements was granted.
Additional Information for Test and Measurement Equipment
If Test and Measurement Equipment is operated with unscreened cables and/or used for measurements on
open setups, the user has to assure that under operating conditions the Radio Interference Limits are still
met at the border of his premises.
3
Safety Considerations
GENERAL - This product and related documenta- source to the product input winng terminals,
tion must be reviewed for familiarization with power cord, or supplied power cord set. Whenever
safety markings and instructions before operation. it is likely that the protection has been impaired,
the product must be made inoperative and be
SAFETY SYMBOLS secured against any unintended operation.
Instruction manual symbol: the product BEFORE APPLYING POWER - Verify that the
will be marked with this symbol when it product is configured to match the available main
is necessary for the user to refer to the power source according to the input power con-
instruction manual in order to protect figuration instructions provided in this manual.
the product against damage.
If this product is to be operated with an autotrans-
former make sure that the common terminal is
Indicates hazardous voltages. connected to the earth terminal of the main power
source.
SERVICING
...L.. Indicates earth (ground) terminal.
WARNING
Any servlcmg, adjustment, maintenance, or
WARNING repair of this product must be performed only
by service-trained personnel.
The WARNING sign denotes a hazard.
It calls attention to a procedure or prac- Adjustments described in this manual may be
tice that, if not correctly performed or performed with power supplied to the product
adhered to, could result in personal in- while protective covers are removed. Energy
jury. Do not proceed beyond a available at many points may, if contacted,
WARNING sign until the indicated result in personal injury.
conditions are fully understood and met.
Capacitors inside this product may still be
charged after the product has been disconnec-
I CAUTION I ted from the main power source.
The CAUTION sign denotes a hazard. To avoid a fire hazard, fuses with the proper
It calls attention to an operating proce- current rating and of the specified type (nor-
dure or practice that, if not correctly mal blow, time delay, etc.) must be used for
performed or adhered to, could result in replacement. To install or remove a fuse, first
damage to or destruction of part or all disconnect the power cord from the device.
of the product. Do not proceed beyond Then, using a small flat-bladed screw driver,
a CAUTION sign until the indicated turn the fuseholder cap counterclockwise until
conditions are fully understood and met. the cap releases. Install either end of a prop-
erly rated fuse into the cap. Next, insert the
SAFETY EARTH GROUND - This is a safety fuse and fuseholder cap into the fuse holder by
class I product and is provided with a protective pressing the cap inward and then turning it
earthing terminal. An uninterruptible safety earth clockwise until it locks in place.
ground must be provided from the main power
4
List of Effective Pages
The List of Effective Pages shows the edition or update number of all pages. Within the manual, any page
changed since the last edition is indicated by printing the update number on the bottom of the page.
Changes are marked with a vertical bar in the margin. If an update is incorporated when an edition is
reprinted, these bars are removed. No information is incorporated into a reprinting unless it appears as a
prior update. To verify that your manual contains the most current information, check that the version
printed at the bottom of the page matches the version listed below for that page.
Effective Pages Version
all .................................................................................. Edition 1
5
Contents
Chapter 1 Page
Product Information 1-1
Introduction .' ................................................................................................ 1-1
Product Description ......................................................................................... 1-1
Documentation Supplied .................................................................................... 1-2
Supporting Documentation .................................................................................. 1-2
Product Structure ............................................................................................ 1-2
Specifications ................................................................................................ 1-2
Serial Number ............................................................................................... 1-2
Supported Eq,uipment ....................................................................................... 1-2
Test Equipment Required .................................................................................... 1-2
Warranty ... "................................................................................................ 1-2
Support Strategy ............................................................................................. 1-2
Chapter 2 Page
Site Planning and Requirements 2-1
Introduction ................................................................................................. 2-1
Site Planning ................................................................................................. 2-1
Specifications ................................................................................................ 2-1
Cabling Limitations .......................................................................................... 2-1
Chapter 3 Page
Installation And Configuration 3-1
Introduction ................................................................................................. 3-1
Shipping Latch ............................................................................................... 3-1
Drive Installation ............................................................................................ 3-2
Primary Power Requirements ............................................................................... 3-2
Controls, Indicators, and Connectors ........................................................................ 3-2
Line- Switch.............................................................................................. 3-2
Channel Address/Diagnostic Switch ...................................................................... 3-2
Run Time Mode ....................................................................................... 3-3
Diagnostic Mode ...................................................................................... 3-3
LED Display .............................................................................................. 3-4
HP-IB Connector ......................................................................................... 3-4
Power Fuse ............................................................................................... 3-4
Line Connector ........................................................................................... 3-4
CPU Connection - HP-IB Systems ........... "............................................................... 3-4
7
Contents (continued)
HP-IB Cabling ............................................................................................ 3-4
HP-IB Device Address .................................................................................... 3-5
Chapter 4 Page
Preventive Maintenance 4-1
Introduction ................................................................................................. 4-1
Chapter 5 Page
Functional Description 5-1
Introduction ................................................................................................. 5-1
Block Diagrams .............................................................................................. 5-2
Signal Notation .............................................................................................. 5-2
List of Mnemonics........................................................................................... 5-2
Disc Format ................................................................................................. 5-3
Addressing Structure ......................................................................................... 5-7
Addressing Mode ............................................................................................ 5-7
Disc Sparing ................................................................................................. 5-7
Sector Sparing ............................................................................................ 5-7
Track Sparing ............................................................................................. 5-8
Controller PCA-A6 .......................................................................................... 5-8
Servo System ................................................................................................ 5-11
Head-Disc Assembly A3 ................................................................................. 5-12
Dedicated Servo Code ................................................................................ 5-12
Sampled Servo Code .................................................................................. 5-13
Servo Head .......................................................................................... 5-13
Servo Read Preamplifier/Write Driver IC........................................................... .5-13
Drive ID Circuit ...................................................................................... 5-13
Head Gain Reference PROM and DAC .............................................................. 5-14
Actuator ..................................................... ~ .. ~ ....................................... 5-14
Speed Sensor .......................................................................................... 5-14
Read/Write PCA-A2..................................................................................... 5-14
Dedicated Servo AGC Amplifier. .................................................................... 5-14
Sampled Servo Switch ................................................................................ 5-15
Sampled Servo AGC Amplifier ....................................................................... 5-15
Servo PCA-Al ........................................................................................... 5-15
Servo Controller ...................................................................................... 5-15
2-Bit ADC ............................................................................................ 5-16
Dedicated Servo AGC Circuit. ....................................................................... 5-17
Sampled Servo AGC Circuit.......................................................................... 5-17
Sector Mark Decoder................................................................................. 5-17
Dedicated Servo Circuit .............................................................................. 5-17
Sampled Servo Circuit ................................................................................ 5-19
8
Contents (continued)
Sampled/Dedicated Select Switch ................................................................... .5-20
Slew Rate Limiter .................................................................................... 5-20
Slew Rate Limit Switch .............................................................................. 5-20
Off-Track Detector................................................................................... 5-20
Track Crossing Detector.................................................................. "........... 5-20
Fault Latches .......................................................................................... 5-21
Servo Power Amplifier ................................................................... "........... 5-21
Amplifier Error Detection ............................................................... , ........... 5-24
Servo System Errors ..................................................................................... 5-25
Track Follower - PLL Errors ......................................................................... 5-25
Seek Errors ............................. "............................................................. 5-26
Power Amplifier Error ................. , ............................................................. 5-26
Error ReIlOrting ........................ "............................................................. 5-27
Flowcharts .... ".......... , .................... "............................................................. 5-27
Read/Write System ........................... , ............................................................. 5-27
Head-Disc Assembly A3 ................................................................................. 5-28
Recording Medil.lm ..................... , ............................................................. 5-28
Read/~'rite Heads .................................................................................... 5-28
Read Preamplifier/Write Driver ICs ... , ............................................................ .5-28
Read/Write PCA-A2..................................................................................... 5-29
Read/~rrite Controller IC ............................................................................ 5-29
Head Select Encoder ................................................................................. 5-32
Read Chain ........................................................................................... 5-32
Write Chain .......................................................................................... 5-33
Read/~rrite System Errors............................................................................ 5-33
Error Reporting ...................................................................................... 5-34
Spindle Drive System ....... , ............................................................................... 5-34
AC Input (:ircuit ........ , ............................................................................... 5-35
Spindle Motor BI ........................................................................................ 5-35
Primary Power PCA-A8 ................................................................................. 5-35
LINE- Switch ........................................................................................ 5-35
Start Capacitor and Relay ............................................................................ 5-35
Brake V'oltage Source................................................................................. 5-36
Speed Sensor ............................................................................................. 5-36
Servo PCA-/\1 ........................................................................................... 5-36
Read/Write PCA-A2..................................................................................... 5-36
Power Distribution PCA-A5 ............................................................................. 5-36
Power Sl.lpply System ....................................................................................... 5-36
AC Input Circuit ........................................................................................ 5-36
Primary Power PCA-A8 ................................................................................. 5-37
Power Supply PCA-A4 .................................................................................. 5-37
Primary Power Selection ............................................................................. 5-37
Primary Control Circuit .............................................................................. 5-37
Output Section........................................................................................ 5-37
Fault Detection and Protection ...................................................................... 5-37
Power Distribution PCA-A5 ............................................................................. 5-37
Read/Write PCA-A2..................................................................................... 5-37
Servo PCA-,I\'] .......................................................................................... 5-38
9
Contents (continued)
LED Display ............................................................................................. 5-38
HDA Air Filtration ......................................................................................... 5-38
Recirculating Filter ...................................................................................... 5-38
Breather Filter ........................................................................................... 5-38
Chemical Filter and Desiccant Chamber ................................................................ 5-38
Drive Air Flow ............................................................................................. 5-38
Chapter 6 Page
Removal And Replacement 6-1
Introduction ................................................................................................. 6-1
Tools Required .............................................................................................. 6-1
Illustrations .................................................................................................. 6-2
Drive Preparation For Service ............................................................................... 6-2
Drive Removal And Replacement Procedures............................................................... 6-2
Rear Cover ............................................................................................... 6-2
HP-IB Assembly .......................................................................................... 6-2
Front Panel ............................................................................................... 6-3
Front Cover .............................................................................................. 6-3
Controller PCA-A6 ....................................................................................... 6-3
EPROM Kit, Controller PCA-A6 ......................................................................... 6-3
Read/Write PCA-A2 ...................................................................................... 6-4
Servo PCA-A I ............................................................................................ 6-4
Power Distribution PCA-A5 .............................................................................. 6-4
Line Filter AssemblyFL 1................................................................................. 6-4
Drive Belt, Motor Pulley ................................................................................. 6-5
Power Supply PCA-A4 ................................................................................... 6-5
Primary Power PCA-A8 .................................................................................. 6-6
Start Capacitor Cl ........................................................................................ 6-6
Motor BI ................................................................................................. 6-7
Head-Disc Assembly A3 .................................................................................. 6-7
Chapter 7 Page
Adjustments 7-1
Introduction ............................................................................................. , ... 7-1
Chapter 8 Page
Troubleshooting and Diagnostics 8-1
Introduction ................................................................................................. 8-1
Safety Considerations ........................................................................................ 8-1
10
Contents (continued)
Troubleshooting Strategy ................................................................................... 8-1
Self-Test Diagnostics ......................................................................................... 8-1
Diagnostic Switch......................................................................................... 8-2
Run Time Mode ....................................................................................... 8-2
Diagnostic Mode ...................................................................................... 8-2
LED Disp]ay .............................................................................................. 8-3
Assembly Id.entification .................................................................................. 8-3
CS/80 External Exerciser .................................................................................... 8-3
Error Logs ................................................................................................... 8-4
Error Rate 'fest (ERT) Log ............................................................................... 8-4
R un Time Log ............................................................................................ 8-4
Fault Log ................................................................................................. 8-5
Error Codes .................................................................................................. 8-5
TERRORS ................................................................................................ 8-6
DERRORS ................................................................................................ 8-6
Servo Controller Error Codes ............................................................................ 8-6
Data Error Troubleshooting ................................................................................. 8-7
Checking Power Supply Voltages ............................................................................ 8-7
Servo Test Point PCA ....................................................................................... 8-8
Read/Write Test Point PCA ................................................................................. 8-8
Chapter 9 Page
Replaceable Parts 9-1
Introduction ................................................................................................. 9-1
Ordering Information ........................................................................................ 9-1
Service Kit Contents ......................................................................................... 9-2
Chapter 10 Page
Reference 10-1
Controller PCi\-A6 .........................................................................................10-1
Chapter 11 Page
Product History 11-1
Introduction ................................................................................................ 11-1
11
Contents (continued)
Chapter 12 Page
Diagrams 12-1
Introduction ................................................................................................ 12-1
Dimensions.................................................................................................. 12-1
Air Circulation................................................................... -....................... 12-1
Assembly Location.......................................................................................... 12-1
Signal Distribution .......................................................................................... 12-1
Functional Block Diagrams ................................................................................. 12-2
Appendix A Page
HP-IB Controller A-I
Introduction ................................................................................................ A-I
Controller Interfaces........................................................................................ A-I
HP-IB .................................................................................................... A-I
HP-IB Communications .............................................................................. A-3
Channel Management ................................................................................ A-4
Message Structure .................................................................................... A-4
CS/80 Instruction Set ................................................................................. A-4
ESI ....................................................................................................... A-5
Disc Data Bus ........................................................................................ A-5
Data Path Control Bus ............................................................................... A-6
Servo Control Bus .................................................................................... A-7
Miscellaneous Signals ................................................................................. A-7
Human Interface ........................................................................................ A-7
Functional Operation ....................................................................................... A-7
Power-Up................................................................................................ A-8
Head Positioning......................................................................................... A-8
Write .................................................................................................... A-8
Read ..................................................................................................... A-9
Error Correction.................................................... "................................... A-I0
Hardware Architecture ................................................ "................................... A-I0
HP-IB Circuitry ..................................................... "................................... A-I0
HP-IB Interface...................................................................................... A-IO
DMA ................................................................................................ A-I0
ESI Circuitry............................................................................................ A-II
Disc Data Interface.................................................................................. A-II
DMA ................................................................................................ A-ii
ECC ...............................................-.. -................................................ A-I2
Data Path Control Interface ........................................................................ A-I2
Servo Control Interface ............................................................................. A-i2
Microprocessor Circuits ................................................................................ A-12
Microprocessor ...................................................................................... A-13
Microprocessor Memory ............................................................................ A-13
Clock Generators .................................................................................... A-13
12
Contents (continued)
Interrupt Controller ................................................................................. A-I3
Bus Error Timer ..................................................................................... A-I3
Human Interface Circuitry ............................................................................. A-I4
HP-IB Address/Selftest Switch ...................................................................... A-I4
LED Drivers ......................................................................................... A-I4
Firmware Architecture .................................................................................... A-I4
Drive Initialization Firmware........................................................................... A-I4
Multi-Tasking Executive ................................................................................ A-I6
Channel Module ........................................................................................ A-I6
Command Preprocessor ................................................................................ A-I7
CS/80 Module .......................................................................................... A-I7
RPS Task ................................................................................................ A-I7
Error Correction Task .................................................................................. A-I8
Diagnostics.................................................................................................. A-I8
Disc Caching ............................................................................................... A-I8
Cache Functional Operation ............................................................................ A-I8
Read With Disc Caching ............................................................................ A-I8
Write With Disc Caching............................................................................ A-I9
Cache Flushing ...................................................................................... A-I9
Cache Hardware ........................................................................................ A-I9
Cache Diagnostics ...................................................................................... A-20
13
Figures and Tables
Figure or Table Page
Figure 1-1. liP 7937 Disc Drives in HP 19511A Cabinet .................................................... 1-3
Figure 3-1. Drive Controls. Connectors, and Indicators ..................................................... 3-6
Figure 3-2. Rear Panel Label Locations ..................................................................... 3-7
Figure 3-3. Maximum Cable Length for HP-IB Channel. ................................................... 3-8
Figure 5-1. Track Format, Logical Vs Physical Addressisng................................................. 5-4
Figure 5-2. Maintenance Tracks............................................................................. 5-5
Figure 5-3. Sector Format ........................................................................... ~ ........ 5-6
Figure 5-4. Addressing Strllcture ............................................................................ 5-9
Figure 5-5. Spare Track Scalar Values...................................................................... 5-10
Figure 5-6. Servo Controller Power On Flowchart. ........................................................ 5-39
Figllre 5-7. Recalibrate Flowchart ......................................................................... 5-41
Figure 5-8. Seek Flowchart ................................................................................. 5-42
Figure 5-9. Bump Seek Flowchart .......................................................................... 5-44
Figure 5-10. Servo Commands Flowchart .................................................................. 5-45
Figure 5-11. Controller Power On Flowchart .............................................................. 5-46
Figure 5-12. Dedicated Servo Code ....................................................................... .5-71
Figure 5-13. Sampled Servo Code .......................................................................... 5-73
Figure 5-14. Dedicated Servo Circuit Timing .............................................................. 5-75
Figure 5-15. Sampled Servo Circuit Timing ................................................................ 5-77
Figure 5-16. Disc Drive Basic Block Diagram .............................................................. 5-79
Figure 6-1. Spring-Type Spindle Lock ....................................................................... 6-9
Figure 6-2. Bracket-Type Spindle Lock ..................................................................... 6-9
Figure 8-1. ERT Log Error Code Byte ...................................................................... 8-9
Figure 8-2. Run Time Log Error Code Byte ................................................................ 8-9
Figure 8-3. Power Supply PCA-A4 Outputs ................................................................ 8-10
Figure 8-4. Servo System Test Point PCA .................................................................. 8-40
Figure 8-5. Read/Write Test Point PCA ................................................................... 8-45
Figure 9-1. Disc Drive, Exploded View ..................................................................... 9-7
Figure 9-2. HP 19511A Cabinet, Exploded View ............................................................ 9-9
Figure 9-3. HP 19512A Rack Slide Kit, Exploded View ...................................................9-11
Figure 12-1. Drive Dimensions ........................................................................... 12-10
Figure 12-2. HP 19511A Cabinet Dimensions ............................................................ 12-11
Figure 12-3. Airflow Within Drive....................................................................... 12-12
Figure 12-4. Location of Assemblies and Parts........................................................... 12-13
Figure 12-5. Primary Power Cable Assembly WI ........................................................ 12-14
Figure 12-6. Power Supply Input Cable Assembly W3 ................................................... 12-15
Figure 12-7. Power Supply Output Cable Assembly W4 ................................................. 12-16
Figure 12-8. Speed Sensor Cable Assembly W5 .......................................................... 12-17
Figure 12-9. Power Jumper Cable Assembly W6 ......................................................... 12-18
Figure 12-10. Signal Jumper Cable Assembly W7 ........................................................ 12-19
Figure 12-11. HDA Cable Assembly W8 ................................................................. 12-20
Figure 12-12. Cabling Diagram ........................................................................... 12-21
Figure 12-13. Servo PCA-Al, Parts Location and Connector Pinout .................................... 12-23
Figure 12-14. R/W PCA-A2, Parts Location and Connector Pinout. .................................... 12-25
Figure 12-15. HDA Assembly A3, Parts Location and Connector Pinout................................ 12-27
Figure 12-16. Power Supply PCA-A4. Parts Location and Connector Pinout. ........................... 12-29
14
Figures and Tables (continued)
Figure 12-17. Power Distribution PCA-AS, Parts Location and Connector Pinout ...................... 12-31
Figure 12-18. LED PCA-A 7, Parts Location and Connector Pinout ..................................... 12-32
Figure 12-19. Primary Power PCA-A8, Parts Location and Connector Pinout .......................... 12-33
Figure 12-20. Servo System, Functional Block Diagram.................................................. 12-35
Figure 12-21. Read/Write System, Functional Block Diagram ........................................... 12-39
Figure 12-22. Spindle Drive System, Functional Block Diagram ......................................... 12-41
Figure 12-23. Power Supply System, Functional Block Diagram ......................................... 12-43
Figure A-I. HP-IB Signal Lines ............................................................................. A-2
Figure A-2. Firmware Architecture ....................................................................... A-IS
Figure A-3. HP-IB Controller PCA-A6 Functional Block Diagram ....................................... A-21
Figure A-4. HP-IB Controller PCA-A6, Parts Location and Connector Pinout ........................... A-23
Table 1-1. Disc Drive, Product Structure.................................................................... 1-4
Table 5-1. List of Mnemonics .............................................................................. 5-48
Table 8-1. External Exerciser Commands .................................................................. 8-11
Table 8-2. List of DERROR/TERRORS ................................................................... 8-15
Table 8-3. Servo System Test Connector Al]3, Mnemonics................................................ 8-41
Table 8-4. Read/Write System Test Fixture, Mnemonics................................................... 8-46
Ta ble 9-1. Disc Drive, Replaceable Parts .................................................................... 9-3
Table 9-2. HP 1951lA Cabinet, Replaceable Parts .......................................................... 9-8
Table 9-3. HP 19512A Rack Slide Kit, Replaceable Parts .................................................. 9-10
Table 9-4. Abbreviations ...................................................................................9-12
Table 9-5. Code List Of Manufacturers .................................................................... 9-13
Table 12-1. Signal Distribution List ........................................................................ 12-3
Table 12-2. Voltage Distribution List ..................................................................... .12-9
Table A-I. HP-IB Definitions .............................................................................. A-3
Table A-2. Universal Command Formats .................................................................. A-3
Table A-3. HP-IB Message Structure ....................................................................... A-5
Table A-4. Supported CS/80 Commands ................................................................... A-6
15
Product Information 1
1-1. INTRODUCTION Head positioning is performed by a rotary actuator
and a dual closed-loop servo positioning system.
This chapter contains product information for the Control of the servo system is derived from the
Hewlett-Packard Model 7936 and 7937 Disc dedicated servo code on the servo surface and also
Drives. The information provided includes a from servo code embedded between data sectors
general description of the HP 7936 and HP 7937, a on all of the data surfaces.
list of equipment supplied, details of the product
structure, test equipment required, and support Mechanical and contamination protection for the
strategy. discs, heads, and rotary actuator is achieved by
enclosing these components in the sealed head-disc
assembly. The head-disc assembly includes a self-
1-2. PRODUCT DESCRIPTION contained air filtration system which supplies clean
air and equalizes temperature throughout the
The HP 7936 and HP 7937 Disc Drives are high- HOA.
performance, random access, data storage devices
designed for use with medium- and large-sized A self-contained power supply in the drive supplies
computer systems. In this manual, unless otherwise dc voltages to the controller and the drive
specified, "drive" refers to both the HP 7936 and electronics. The standard drive is configured for
HP 7937. operation from a 90-132V, 60 Hz power source.
Options 015 and 017 permit operation from 50 Hz
A microprocessor-based controller is factory- and 180-264V, respectively.
installed in the drive to provide an interface to the
host computer. Two HP-IB controllers are avail- The drive is contained in an enclosed housing and
able for this purpose. In the HP 7936H and HP is fitted with removable covers to permit easy ac-
7937H Disc Drives, interface to the host is via an cess for servicing. A total of two drives can be in-
Hewlett-Packard Interface Bus (HP-IB) controller. stalled on the rack slides of a desk-height HP
In the HP 7936XP and HP 7937XP, the controller 1951lA Cabinet. See figure 1-1. An HP 19512A
has HP-IB Cache added. Both of the controllers Rack Slide Kit is available for mounting the drive
interface with the drive electronics via an in an EIA 19-inch rack cabinet. A special lifter
HP-developed standard interface (ESI). tool makes it possible for one person to install the
56.7 kg (125 lb) drive in either cabinet.
A sealed head-disc assembly (HOA) in the drive ...
contains a spindle with a stack of seven non- An upgrade kit is available for the drive: HP
removable 210-millimetre (8.3-inch) diameter discs. 97521A Controller Cache Upgrade.
The spindle is belt-driven by a motor mounted ad-
jacent to the sealed HOA. There are seven (HP Self-test diagnostics and a fault-finding system
7936) or 13 (HP 7937) thin-film surfaces on the contained within the drive exercise key functions
discs for data storage. An additional surface is used of its operation. Self test is performed automati-
for dedicated servo code. cally at power on and also can be initiated by the
host. Drive status is indicated by three light-
The formatted storage capacity of the drive is 307 emitting diodes (LEOs) on the front panel. See
megabytes (HP 7936) or 571 megabytes (HP 7937). figure 3-1. In the event of a self-test failure, the
Each data surface uses a movable read/write head LEOs will identify the failed subassembly in the
to service its data tracks. The bottom surface of drive.
the lowest disc in the stack contains prerecorded
servo code which is used to position the read/write
heads over the desired data track.
1-1
Product Information
7936 and 7937
1-3. DOCUMENTATION SUPPLIED number and full serial number should be quoted in
any communication with Hewlett-Packard regard-
The drive is supplied with one each of the follow- ing the drive.
ing publications: