Cal-Comp 142 User manual

CalComp Model 140 & Model 142
Floppy Disk Drives
Technical Manual

MODEL 140 AND MODEL 142
FLOPPY DISK DRIVES
TECHNICAL MANUAL
April 1977
California Computer Products, Inc.
2411 W. La Palma, Anaheim, CA 92801
Part No. 10150-901-003·2

REVISION
-1
-2
Model 140/142 Technical Manual
PUBLICATIONS RECORD.
NOTES
Expands coverage to include the Model 142 and all versions of the Model 140.
Incorporates the intent of Technical Bulletin D178 and Field Change Notice DFOOS.
Incorporates latest changes as per Small Disk Operations
Copyright © 1976, 1977 by
CALIFORNIA COMPUTER PRODUCTS, INC.
Printed in the United States of America

CONTENTS
Section
Page
INTRODUCTION
Description ............................................................... 1-1
Physical and Electrical Characteristics.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Special Tools and Test Equipment ................................................ 1-3
2 INSTALLATION AND OPERATION
Unpacking
................................................................ 2-1
Installation ................................................................ 2-1
Ac Power Cable .......................................................... 2-1
Dc and Signal Cabling ...................................................... 2-1
Data Output Selection ...................................................... 2-6
Checkout ........ ~ ...................................................... 2-6
Operation ................................................................ 2-6
Floppy Disk Storage and Handling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Write-Protect Option ...................................................... 2-7
Floppy Disk Loading and Unloading ............................................ 2-7
3 THEORY OF OPERATION
Principles
of Operation ...................................................... 3-1
Recording Medium ........................................................ 3-1
Data Recording Method .................................................... 3-2
Peak Shift Precompensation .................................................. 3-3
Track Accessing
.......................................................... 3-3
Read
Data Timing ........................................................ 3-3
Write
Data Timing ........................................................ 3-3
Power-On to Data Transfer .................................................. 3-6
Functional Areas ........................................................... 3-6
Control System .......................................................... 3-6
Positioning System ........................................................ 3-8
Read/Write System ........................................................ 3-9
Mechanical System .......................................................... 3-9
Drive Mechanism .......................................................... 3-9
Disk Centering Mechanism .................................................. 3-10
Head Load Mechanism ...................................................... 3-10
Positioning Mechanism ...................................................... 3-10
Logic Symbology and Definitions ................................................ 3-11
Detailed Logic Description
.................................................... 3-11
Control Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Read/Write Head Positioning Logic
............................................ 3-16
Read/Write Logic
........................................................ 3-19
+17 vdc Regulator Description ................................................ 3-24
Read Decoder
with PLO Assembly .............................................. 3-25
Normal PLO Operation .................................................... 3-26
Missing-Pulse
PLO Operation .................................................. 3-27
Sync-Up PLO Operation .................................................... 3-27
Data Decoder .............................................................. 3-27
Read Sync .............. ' .................................................. 3-29
iii

CONTENTS (Continued)
Section Page
4 MAINTENANCE
Preventive Maintenance
...................................................... 4-1
Monthly (covers on) ...................................................... 4-1
Semiannually (covers removed) ................................................ 4-1
Disk Drive Exerciser ........................................................ 4-1
Controls~ Indicators~ and Test Points ............................................ 4-1
Preparation for Offline Checkout .............................................. 4-1
Disconnecting the Exerciser .................................................. 4-3
Maintenance Procedures
...................................................... 4-3
Tools and Test
Equipment .................................................. 4-3
Plugs and Jacks
.......................................................... 4-3
PWB Assembly ~ Data and Control .............................................. 4-4
PWB Replacement ........................................................ 4-4
Power ................................................................ 4-4
Drive System
............................................................ 4-5
Spindle System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-9
Position System .......................................................... 4-10
Read/Write System ........................................................ 4-12
Data Decoder with PLO Board Adjustments ...................................... 4-13
5 ILLUSTRATED PARTS BREAKDOWN
Figure
1-1
2-1
2-2
2-3
2-4
2-5
2-6
2-7
3-1
3-2
3-3
3-4
3-5
iv
Group Assembly Parts List .................................................... 5-1
Figure and Item Number ....................................................... 5-1
Part Number .............................................................. 5-1
Description .............................................................. 5-1
Quantity Per Assembly ...................................................... 5-1
Usage Code .............................................................. 5-1
Purchased Parts ............................................................ 5-2
Accessories .............................................................. 5-2
ILLUSTRATIONS
Page
Floppy Disk Drive .......................................................... 1-1
Disk Drive Shipping Configuration ................................................ 2-1
Ac Power Cabling Wiring ...................................................... 2-2
Twisted Pair Interface Connector Board, Schematic Diagram .............................. 2-2
Ribbon Cable Interface Connector Board, Schematic Diagram .............................. 2-3
Termination for Disk Drive Output Signals .......................................... 2-4
Termination for Disk Drive Input Signals .......................................... 2-4
Floppy Disk wading ........................................................ 2-7
Flexible Disk Construction .................................................... 3-1
Code Format Comparisons and MFM Characteristics .................................... 3-2
Peak Shifting and Precompensation Conditions ...................................... 3-4
Track Accessing Timing
...................................................... 3-5
Double Frequency Raw Data Timing ......•....................................... 3-5

Section
3-6
3-7
3-8
3-9
3-10
3-11
3-12
3-13
3-14
3-15
3-16
3-16
3-17
3-18
3-19
3-20
3-21
3-22
3-23
3-24
3-25
3-26
3-27
3-28
3-29
3-30
3-31
3-32
3-33
3-34
3-35
3-36
3-37
3-38
3-39
3-40
3-41
3-42
3-43
3-44
3-45
3-46
3-47
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
ILLUSTRATIONS (Continued)
Page
MFM Raw Data Timing ...................................................... 3-5
Double
Frequency Write Data Timing ............................................ 3-6
MFM Write Data Timing
...................................................... 3-6
Power-On to Write Timing .................................................... 3-7
Power-On to Read Timing .................................................... 3-7
Disk Drive General Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Disk Drive Mechanical System Pictorial View
........................................ 3-9
Drive Mechanism
........................................................... 3-10
Disk Centering and Head Load Mechanism .......................................... 3-10
Positioning Mechanism ........................................................ 3-11
Logic Symbology (Sheet 1
of 2) ................................................ 3-12
Logic Symbology (Sheet 2
of 2) ................................................ 3-13
Detailed Block Diagram
...................................................... 3-14
Index Pulse Detection on Speed Monitor, Simplified Logic Diagram ........................ 3-15
Index Dector .............................................................. 3-15
Ramp Generator
............................................................ 3-16
Power-On to Ready Transition Period Waveforms ...................................... 3-16
Head
Load Relay Driver ...................................................... 3-16
Single-Track Positioning Time Waveforms
........................................... 3-17
Multiple-Track Positioning Time Waveforms
.......................................... 3-17
Stepper Motor Position Control Simplified Logic Diagram ................................ 3-17
Stepper Motor Direction Sequencing .............................................. 3-18
Decode and Current Drivers for
00 Code ........................................... 3-18
Track
00 Detector Circuit ...................................................... 3-19
Write Channel, Simplified Logic Diagram
............................................ 3-20
Double-Frequency Write Control and Write Coils Current Flow ............................ 3-21
MFM Write Control and Write Coil Current
Flow ...................................... 3-21
Read/Write Matrix Gate for Read
................................................ 3-23
Differentiator
Input/Output Waveforms ............................................ 3-23
Raw Data
Output Gating ...................................................... 3-23
MFM Raw Read
Data Waveforms ................................................ 3-24
One-Shot Data Decoders ...................................................... 3-24
RAW and
NRZ Read Data Decoder Waveforms ...................................... 3-25
Read Decoder with PLO Block Diagram
............................................ 3-25
PLO, Simplified Logic Diagram .................................................. 3-26
PLO Locked On and Missing Pulse Operation ........................................ 3-26
PLO Sync-Up .............................................................. 3-28
Read/Write Coding Waveforms
.................................................. 3-28
Data Decoder. Simplified Logic Diagram
............................................ 3-29
Data Decoder Waveforms
...................................................... 3-30
Read Data Decoder Sync, Simplified Logic Diagram .................................... 3-30
Composite MFM
Data Decoder Waveforms .......................................... 3-31
Composite Double Frequency Data Decoder Waveforms ................................. 3·32
Model 2140 Disk Drive Exerciser ................................................ 4·1
Exerciser and Disk Drive Setup .................................................. 4-3
Disk Drive Interconnecting Cabling Daigram
........................................ 4·3
Drive System Component Identification ............................................ 4·5
Drive Belt Checks and Adjustments .............................................. 4-5
Head Alignment Waveform .................................................... 4·7
Index Pulse Timing Waveform .................................................. 4-7
Index Pulse with Hard-Sector
Option Timing Waveform, ............ , ................... , 4-8
v

Figure
4-9
4-10
4-11
4-12
4-13
5-1
5-1
5-2
5-3
5-4
5-4A
5-4B
5-4C
5-4D
5-4E
5-4F
5-5
5-6
ILLUSTRATIONS (Continued)
Page
Spindle System Component Identification ....................................... , ... 4-9
Positioning System
Component Identification ........................................ 4-10
Track 00 Alignment Waveform .................................................. 4-11
Head Load Check and Adjustment
................................................ 4-12
Data Separator One-Shot Alignment Waveform
........................................ 4-13
Model 140 Series and 142 Disk Drive Unit (Sheet 1
of 2) ................................ 5-4
Model 140 and 142 Disk Drive Unit (Sheet 2
of 2) .................................... 5-6
Cone Lift Cover Assembly ..................................................... 5-9
Drive Motor Assembly
........................................................ 5-11
Data and Control Board Assembly, VR49
.......................................... 5-13
Data and Control Board Assembly, VR56
.......................................... 5-17
Data and Control Board Assembly, VR57
.......................................... 5-21
Data and Control Board Assembly, VR58
.......................................... 5-25
Data and Control Board Assembly,
VR60 .......................................... 5-29
Data and Control Board Assembly, VR82
.......................................... 5-33
Data and Control Board Assembly, VR83
.......................................... 5·37
Data Decoder with PLO Board Assembly, VR71 ...................................... 5-41
Data Decoder with PLO Board Assembly, VR81
...................................... 5·43
TABLES
Table Page
1-1 Physical and Electrical Characteristics .............................................. 1-2
1-2 Tools and Test Equipment .................................................... 1-3
2-1 Ac Power Cable ............................................................ 2·2
2-2 Twisted-Pair Interface Signal Cable Connections ...................................... 2-5
3-1 Binary Code for In-Out Read/Write Head Positioning .................................. 3-18
4-1 Exerciser Switch, Indicator, and Test Point Functions .................................. 4-2
4·2 Initial Exerciser Control Settings ................................................ 4-3
4-3
Jack and Plug Description .................................................... 4-4
4·4 Power Requirements ........................................................ 4-4
5-1 Unit Options .............................................................. 5-3
vi

SECTION 1
INTRODUCTION
This manual contains installation and operating instructions,
theory
of operation, maintenance procedures, and
illustrated parts breakdown for the Model 140 and
Model 142 Floppy Disk Drives (Figure 1-1). The Model 140
and 142 are compact, high-speed, random-access data
storage units
that use a flexible disk cartridge as the storage
medium. Wherever differences between models exist, they
are identified.
Before performing preventive or corrective maintenance
on
the disk drives, maintenance personnel should become
familiar with the electrical characteristics and principles
of
operation of the disk drives.
Figure 1-1. Floppy Disk Drive
This manual
is intended as a technical guide for field
engineers and other technical personnel who are involved
in maintaining the disk drives. The information in this
manual -other than that contained in this section - is
divided into four basic sections.
• Installation and Operation
Uncrating
Installation
Operation
• Theory of Operation
Principles of Operation
Functional Theory
• Maintenance
Preventive Maintenance
Main tenance Proce du res
• Illustrated Parts Breakdown
DESCRIPTION
The Floppy Disk Drive is a high-speed, random.access
memory device
that is used for data storage in data pro-
cessing systems. The disk drive is compact and except for
power supplies
is self contained. The disk drive can be
rack mounted
or used as a table top unit.
The disk drive uses a removable, flexible disk cartridge
that is easily installed or removed through an access slot
on the front of the disk drive. Removable covers allow
access to the interior
of the disk drive for maintenance
purposes.
PHYSICAL AND ELECTRICAL CHARACTERISTICS
Physical and electrical characteristics for the disk drives
are listed in Table 1·1.
1-1

TABLE 1-1. PHYSICAL AND ELECTRICAL CHARACTERISTICS
Physical Characteristics
Height
Width
Depth
Weight
Power Requirements
Ac Power
Ac Starting Current
Ac Operating Current
Dc Power
Operating Environment
Temperature
Relative Humidity
Heat Dissipation
Specificahons
Disk Cartridge Capacity
Double Density (Unformatted*)
Per Disk
Per Track
Double Density (Hard Sector*)
Per Disk
Per Track
Per Sector
Single Density (Unformatted)
Per Disk
Per Track
Single Density (Hard Sector)
Per Disk
Per Track
Single Density (IBM 3740 Format)
Per Disk
Per Track
Per Sector
Carriage Positioning Time
*Used only with the Mode1142
1-2
4.90 inches
8.40 inches
15.00 inches (add 3 inches for connector clearance)
16 pounds;
18 pounds shipping
100 to 240 vac, +10%, -20%,50 ±0.5 Hz or 60 ±0.5 Hz, single phase
1.7 amperes maximum, 60
Hz; 1.7 amperes maximum, 50 Hz
1.2 amperes maximum, 60 Hz
1.1 amperes maximum, 50 Hz
+24v ±5% at 1.5 amperes maximum, 100 millivolts peak-to-peak ripple
+5v ±5% at 1.0 ampere maximum, 50 millivolts peak-to-peak ripple
600F to 100°F (20°F maximum rate of change per hour)
20% to 80% (no condensation)
275 Btu per hour
6,416,256 bits/802,032 bytes
83,328
bits/l0,416 bytes
6,179,712 bits/772,464 bytes
80,256 bits/l0,032 bytes
2,508 bits
3,208,128 bits/401,016 bytes
41,664 bits/5,208 bytes
3,089,856 bits/386,232 bytes
40,128 bits/5,016 bytes
1,943,552 bits/292,944 bytes
26,644 bits/3,328 bytes
1,024 bits/128 bytes
160 milliseconds (average)
6 milliseconds track-to-track slew (minimum)

TABLE 1-1. PHYSICAL AND ELECTRICAL CHARACTERISTICS (Continued)
Specifications (continued)
Head Settling Time
Head Load Time
Recording
Format
Recording Format
Recording Method
Data Transfer Rate
Data Bit Cell Time
Rotational Speed
Rotational Latency
Average
Maximum
Recording Tracks
Track Spacing
Bit Density
Track Density
Recorded Track Width
Start Time
SPECIAL TOOLS AND TEST EQUIPMENT
10 milliseconds (maximum)
30 milliseconds (maximum)
Fixed or variable length
Fixed
or variable length
140 or 142: Double frequency, frequency modulated (FM)
142 only: Double frequency (FM) double density, modified
frequency modulation (MFM)
FM:
250,000 bits per second
MFM: 500,000 bits per second
2 microseconds
360 rpm ±2.5%
83.3 milliseconds
167 milliseconds
77
0.0208 inch (nominal)
FM:
3268 bits per inch (inside track)
MFM: 6536 bits per inch (inside track)
48 tracks per inch
0.013 inch (nominal)
2.5 seconds (drive ready)
Tools and test equipment recommended for use in
maintaining the floppy disk drives are listed in Table 1·2.
TABLE 1-2. TOOLS AND TEST EQUIPMENT
Tools
Common Hand Tools
Flashlight
Test Equipment
YOM
Oscilloscope
Model
2140 Exerciser
Head Alignment Disk Cartridge
Cleaning Materials
Alcohol (91%solution)
Lint-free cloth
1-3

SECTION 2
INSTALLATION AND OPERATION
This section contains procedures and descriptive material
to aid trained personnel in unpacking, installing, and pre-
paring disk drives for online operation. This section is
divided into three basic parts relating to task-oriented
objectives.
• Unpacking
Unwrapping
Inspection
• Installation
Cable fabrication, connection, and checkout
Preoperational checks
Operational checks
• Operation
The disk drive
is packaged to ensure adequate protection
for local, long distance, or overseas shipping and handling.
Unpack and remove the unit from the shipping container
as soon as it is received (see Figure 2-1).
Figure 2-1, Disk Drive Shipping Configuration
UNPACKING
The following procedure is based on current packing
methods and may be subject
to minor deviations. After
inspecting the container for obvious shipping damage,
proceed
as follows:
1.
Cut and discard the fiberglass straps that secure the
shipping container.
Note
Do not lift the disk drive by the floppy disk
loading handle,
as the handle can be damaged.
2. Remove all parts from the shipping container. Re-
move the inner packing material.
3. Check each part against the packing list.
4. Inspect all items visually for physical damage.
INSTALLATION
Most new installations will normally require that a power
cable and a
dc and signal cable be fabricated on site.
Ac Power Cable
The length of the ac power cable is determined at the
installation site. Cable connectors are supplied with the
disk drive.
CAUTION
Ensure that the power to be applied to the
disk drive corresponds to the requirements
specified
on the nameplate of the disk drive.
Fabricate the ac power cable in a phase-to-neutral or in a
phase-to-phase configuration in accordance with Table
2-1
and Figure 2·2.
Dc and Signal Cabling
Dc and signal cable connections between the controller and
disk drives may be in either a radial or a daisy-chain
arrangement. Two types
of interface connector boards are
2-1

available to accommodate both applications. There are two
versions of each connector board -terminated and unter-
minated.
Pin
1
2
3
JO
2
3
JO
2
3
TABLE 2-1. AC POWER CABLE
Connector 90606-003
Phase-to-Neutral
115/208 vac
Chassis Gnd
115/208 vac
PHASE-TO-NEUTRAL
2 AMP SLO-BLOW
PHASE-TO-PHASE
1 AMP SLO-BLOW
1 AMP SLO-BLOW
Phase-to-Phase
208 vac
Chassis Gnd
208 vac
115/208 VAC (HOT)
CHASSIS
GND (EARTH)
115/208 (RTN)
230 VAC (HOT)
CHASSIS
GND (EARTH)
230 VAC (HOT>
Figure 2-2. Ac Power Cable Wiring
One type of interface connector board is designed for
twisted-pair wiring, which
must be soldered to the board.
The
part number for this board is 12084-001 with terminat-
ing resistors and 12084-002
without terminating resistors
(see Figure 2-3).
The other type of interface connector board is designed for
ribbon cable, which has press-on connectors
that plug into
the interface connector board. The part number for both
the terminated and unterminated boards is 16292-001;
however, the terminated board must have terminating net-
work 16557-001 plugged into IC socket XA2 (see
Figure 2-4).
Fabricated dc and signal cables may be ordered from the
factory or the cables can be fabricated on site.
2-2
+5V 02 1--_--------...".::--0
+5V 04
HEAD LOADI 20 1--+------1 ....... ----..,;;..--0
SELECTI 18 t---+--~---------o
DIRECTION 06 1--+------1 ..... ---- ....... --0
STEPI 08 ~+---___4Ir+-----.-::-:=o
ABOVE TRK 431 24 ~+---___4Ir+-~~--.-::-~
WRITE DATAl
Rll
220
R13
220
PWB
EYELETS
WRITE
ENABLEI 34 t--+---___4I ..... -=-:--:----t":-:::-:-O
+24V
RlS
220
+24V 10 ............ --------~:-::-<>
+24V 12
+24V 14
TRACK 001 18 I-----------~:-=O
READYI 22 1----------- ..... --0
INDEXI 26 I-----------~:-:-O
SECTORI 28 ..----------~~
WRITE ENABLED! 30 ..----------._=_::::-=-o
(READ DATA/)* 361-----------._=_:::_=<>
(READ CLOCKf)*
RAW DATAl
() *USED WITH SINGLE DENSITY RECORDING (FM)
NOTES;
1. PART NO. 12084-001
SHOWN; PART NO.
12084-002 DOES
NOT HAVE TERMINATING
RESISTORS
2. ALL ODD-NUMBERED
PINS ON PI ARE
GROUNDED
Figure 2-3. Twisted Pair Interface Connector Board,
Schematic Diagram

POWER
CONNECTOR
+5
OV
+24
READY 1/
READY 2!
READY 3/
READY 4/
SELECT 11
SELECT 2!
SELECT 3/
SELECT 41
RIBBON CABLE
CONNECTOR
DIRECTION OUT I
STEPI
ATRK 43!
WRT DATA!
WRT GATEI
HEAD LOAD!
TRKOO/
IDXI
SECTOR!
WRTENABLED/
RDATAI
RCLOCKI
J2
,.....-
01
02
~
03
10...-
Jl
,.....-
22
04
02
40
16
14
12
10
06
08
24
32
34
20
18
26
28
30
36
38
10...-
(NOTE 3)
NOTES:
1
2
3
4
5
6
7
8
~
2
~
4
~
6
r
1. JUMPER ONE READY/ SIGNAL AND ONE SELECT/SIGNAL
2. INSTALL TERMINATING NETWORK 16557-001 IF REQUIRED
3. ALL ODD-NUMBERED PINS FOR Jl AND PI ARE GROUNDED
XAI
16
L.!.U
' .... -- ---,,'
~
13
(NOTE 1)
12
....... --- - -,'"
11
1
10
T
9 1
XA2
~
13 +SV
12
(NOTE 2)
~
~
9
~
PI
~
22
~
02
"-
04
10
12
14
16
24
08
06
20
34
32
18
26
28
30
36
38
L..-,..I
DISI(
DRIVE
CONNECTOR
(NOTE 3)
Figure 2-4. Ribbon Cable Interface Connector Board, Schematic Diagram
• Daisy-Chained Application
Daisy-chaining
of multiple disk drives requires the use of
both terminated and unterminated interface connector
boards. The common I/O signals are daisy-chained from
drive to drive; the interface connector board for the last
disk drive
in the chain is a terminated board (see Figures
2-5 and 2-6) that provides line terminations for all
inCOming
signals to the disk drive.
The twisted-pair connector board has feedthrough solder
lands with two eyelets in each land. System cabling can be
accomplished by connecting signal and associated ground
leads
to one eyelet of the respective lands. The remaining
eyelet
of each land can be used to cable signal and associated
ground leads
to the next disk drive interface connector
board. This technique can be used to interconnect the
remaining disk drives.
The ribbon-cable interface connector board allows inter-
connection
of disk drives and a controller through a ribbon
cable. The ribbon cable has press-on connectors at various
intervals that plug into ribbon cable interface connector
boards at the disk drives.
Up to four disk drives can be
connected
to the controller through one ribbon cable.
Note
The SELECT/ signal and its associated ground
and the READ Y/ signal and its associated
ground
should not be daisy-chained in multi-
ple disk drive applications. They
should be
connected to the controller separately. (When
using the ribbon-cable interface
connector
board, SELECT/ and READ Y/ must be jumped
[or the appropriate disk drive.)

OPENCOLLECTO;- -- -- -- I R!BBONCAru INTERFACE --,
POWER GATE * Jl PI 16292-001 VN45 Jl
...... -+- ...
SIGNAL
DISK DRIVE I
_ NO~ _____ -.L ____ .......J
OPENCOLLEcTO'R -- -- -- T -;U;B;,;c;B~~C~
POWER GATE * Jl PI 16292-001 VN45 Jl
SIGNAL
DISK DRIVE
NO.2
...... --9- ...
-.L _____ J
FROM NEXT
DISK DRIVE
r-+S'v----.---
2200
3300
L __ ~~E_R ____ _
PART
OF
RIBBON CABLE
* DRIVE LINE CAPABLE
OF SINKING
36 MA.
Figure 2-5. Termination for Disk Drive Output Signals
- -- -- -- -- -- -- -,- IUBOONCABLE INTERFAcE -,
I 16292-001 VN45
Jl PI ~J~I~_~
DISK DRIVE
_~1 _____ -L ____ -1
-------T----,
Jl PI 2200
Jl
+5V _Af',.J'-~
3300
LAST DISK DRIVE RIBBON CABLE INTERFACE J
_ ~T~ ________ ...L ~~1 ~~ __
PART OF
RIBBON
CABLE
I - QpENCOLLmO;- -- --
POWER GATE
* SIGNAL
L __ C~R~E~ __ _
PART
OF
RIBBON CABLE
* CONTROLLER DRIVE LINE
MUST BE CAPABLE OF
SINKING 25 MA.
** RESISTORS ARE LOCATED
ON TERMINATOR 15198-001
PLUG WHICH IS INSTALLED
IN INTERFACE KIT BOARD
OF LAST DISK DRIVE.
Figure 2-6. Termination for Disk Drive Input Signals
2-4

• Radial Application
When disk drives are connected radially to a controller,
separate
dc and signal cables radiate from the controller to
each
disk drive. A terminated interface connector board
must be used for each disk drive.
• Twisted-Pair Dc and Signal Cable Fabrication
The twisted-pair dc and signal cable should consist
of
twisted pairs (approximately 30 twists per foot) whose
wire size
is either No. 24 or No. 26 AWG and not
exceeding 25 feet in length.
1. Fabricate the twisted-pair dc and signal cable in
accordance with Table 2-2.
Use Cable Terminator
Assembly 12084·001
if terminations are required;
use Cable Terminator Assembly 12084-002
if termi-
nations are not required.
2.
Use a YOM to check each cable for pin-to-pin shorts.
3.
Use a YOM to check for continuity between corre-
sponding pins at opposite ends
of each cable.
4. Connect the dc and signal cable to the controller.
5. Apply power to the controller, and check each
interface connector board to verify proper pin
assignments. Refer to Table 2-2.
6. Turn power off at the controller, and connect the
cables to the disk drives.
TABLE 2-2. TWISTED·PAIR INTERFACE SIGNAL CABLE CONNECTIONS
Signal Pin Ground Pin
Signal Number Eyelet Connection Eyelet Connection Number Eyelet Connection Eyelet Connection
From Controller
or
To Next Drive From Controller
or
To Next Drive
Preceding Drive Preceding
Driv.e
READ CLOCK** or 38 E37 E77 37 E38 E78
RAW DATA
READDATA** 36 E35 E75 35 E36 E76
PLO SYNC/* 40 E33 E73 39 E34 E74
WRITE DATA/ 34
E31
E71
33 E32 E72
WRITE ENABLE/
32 E29 E69
31
E30 E70
ABOVE TRACK
43/
24 E27 E67 23 E28 E68
WRITE ENABLED/
30
E25 E65 29 E26 E66
SECTOR! 28 E23 E63 27 E24 E64
INDEX/ 26
E21 E61 25 E22 E62
READY! 22 E19 - 21
E20 -
HEAD LOAD! 20 E47 E49
19
E48 E50
TRACK
00/
18 E17 E57
17
E18 E58
+24V
14
E15 E55
13 E16 E56
+24V 12 E13 E53
11 E14 E54
+24V 10
Ell
E51 9 E12 E52
SELECT! 16 E9 - 15
EI0
-
DIRECTION 6 E7 E45 5 E8 E46
STEP/ 8
E5
E43 7 E6 E44
+5V 4
E3
E41
3 E4 E42
+5V 2
El E39 1 E2 E40
*Not Used
·*When unseparated data is the output of the disk drive, pin 38 supplies the unseparated data (raw data) and read data output (pin 36) is
not used.
2-5

• Ribbon Signal Cable Fabrication
The ribbon signal cable should consist
of a 40-conductor
ribbon signal cable (3M part number 3365/40 or equivalent)
and one or more 40-pin connector (3M part number
3417-0000,3417-3000, or equivalent) depending on the
number
of disk drives to be connected to the controller
through the same cable.
1. With the use of a small arbor press, press the 40-pin
connectors onto the ribbon cable at a predetermined
interval.
2.
3.
4.
Use a VOM to check each connector for pin-to-pin
shorts.
Use a VOM to check for continuity between
corresponding pins
at each connector.
Connect the cable to the disk drives and to the
controller.
• Dc Power Cable Fabrication
When a ribbon cable
is used to connect the controller to
the disk drives, a separate, 3-wire, dc power cable must be
fabricated for each disk drive.
1.
2.
3.
Crimp contacts (CalComp part number 90441-002)
on one end of each wire.
Insert contacts into the plug housing (CalComp
part number 90605-003). Verify that the contacts
are inserted into the proper position in the plug
(see
J2 of Figure 2-4).
Connect a dc power cable
to each disk drive.
Data Output Selection
The disk drive can be adapted to either
of two decode
outputs: separated data
or unseparated data (raw data). If
separated data is desired, make certain that Floppy Disk
Plug Assembly 14519-001 is installed in IC socket A6.
Assembly 14519-001 has jumpers between pins 4 and 11,
pins 5 and 10, and pins 3 and 12.
If unseparated data is
desired, make certain that Floppy Disk Plug Assembly
14519-002 is installed in IC socket A6. Assembly 14519-002
has a jumper between pins 4 and S.
Checkout
The disk drive can
be checked out operationally by
running the disk drive either offline with the exerciser or
online with the system.
2-6
OPERATION
Floppy disk storage and handling as well as correct operat-
ing procedures are important for error-free operation.
Floppy Disk Storage and Handling
Since the recorded disk contains vital information.
reasonable care should be exercised in its handling. Longer
disk life and trouble-free operation will result
if the
following recommendations
are followed.
• Floppy disk ID information should be written on an
adhesive-type tape
or label; then the label should be
affixed to the disk cartridge covering. Writing directly
on the floppy disk covering would damage the surface
of the disk.
• Do not fasten paper clips to the edges of the disk
jacket.
• Do not touch the surface of the disk exposed by the
jacket slot.
• Do not clean the disk in any manner.
• Keep the disk away from magnetic fields and away
from ferromagnetic materials that may
be magnetized.
• Return the disk to its protective envelope when removed
from the disk drive.
• Protect each disk from liquids, dust, and metallic
substances at all times.
• Do not exceed the following environmental storage
conditions:
Temperature: SooF to 1200F (lOoC to
4B.9
0
C)
Relative Humidity: B% to BO%
Maximum Wet Bulb: BooF (26.70C)
• Disks should be stored when not
in use.
Before using a floppy disk on a disk drive after long-term
storage, the floppy disk should be allowed to stabilize
in
the disk drive environment one hour for each hour out of
the disk drive environment (up to 24 hours).
For short-term storage, the floppy disk(s) should be placed
temporarily
in the same area as the disk drive. No more
than ten floppy disks should be stacked in a flat me.

Write-Protect Option
The data recorded
on a floppy disk can be stored perma-
nently by using the write-protect option.
If the floppy
disk
is intended to be used only for reading, verify that an
opaque tab is
not affixed over the write-protect hole (see
Figure 3-1) in the floppy disk jacket. To enable data record-
ing, the tab must be installed.
Floppy Disk Loading and Unloading
Proper loading
of the floppy disk is vital to the operation
of the disk drive. Figure 2-7 shows the location of the
floppy disk opening for loading.
A. FLOPPY DISK IN LOAD POSITION
The procedure for loading/unloading the floppy disk is as
follows:
1.
2.
3.
4.
5.
Move the handle to the open position.
Insert the floppy disk in the load aperture as shown
in Figure 2-7. (Ensure that the head aperture is to
the rear and that the label faces the handle).
Move the handle to the disk load position; verify
that the cover latches securely in place.
To unload the floppy disk, press the release
button on
the handle. The load mechanism disengages the floppy
disk from the drive mechanism.
Remove the floppy disk, and close the cover.
B. FLOPPY DISK LOADED
Figure 2-7. Floppy Disk Loading
2-7

SECTION 3
THEORY OF OPERATION
This section contains descriptions of the characteristics and
the basic principles
of operation of the Model 140 and the
Model 142 Floppy Disk Drives.
It also contains functional
descriptions
of various operating systems and the digital
logic and analog circuits employed in this device.
Recording Medium
The disk drives use a removable, flexible disk as the
storage medium. Figure 3-1 shows the construction and
dimensions
of a typical flexible disk and associated jacket.
Only one side is used for recording.
PRINCIPLES OF OPERATION
Certain hardware and operational characteristics of the
disk drive must be understood
as a basis for more detailed
study
offunctional systems and circuits. The following
principles
of operation provide this necessary background
information.
The recording medium specified for use with the Model
140 and the Model 142 is a single-side oxide-coated,
flexible disk enclosed within a protective plastic jacket.
(Figure
3-1 B). The protective jacket contains apertures
for spindle loading, head contact, sector/index detection,
and write-protect detection.
SEALED
PROTECTIVE
JACKET
I~------------ BIN. ------------.~I
BIN.
I
\
/
/
I
",-- -- ---
~ .........
,/
/
\ HEAD SPINDLE/HUB /
\<~:~R~_~:E~//
SEALED O.06IN.
PROTECTIVE _ I
JACKET ~, J
LI N ER ceo TH . ':'::""'\':'.~::::::.:.:,.,:. -rl-
SIDES OF OISK)/~ f
~ OXIDE-COATED
MYLAR DISK
1.5IN.DIA
LINER
WRITE-
PROTECT
HOLE
7.B IN 'AlDIA ~ REGISTRATION OPTIONAL SECTOR
1.5iN. 7'---' OPENING ~~-;<HOLES O.lOODIA
RADIUS I ""\ INDEX / /
((' ,/-~'"-\ \ ~···O\
INOEX \. If I J \.. .j
HOLE rf' ~_/ ...
TRACK 00 -
TRACK 76 CD
Figure 3·1. Flexible Disk Construction