Quantum Q2000 User manual

ounRlum
OEM
MANUAL
Q2000
8" MediaFixed Disk Drive

QUANTUM CORPORATION
2150 Bering Drive
San Jose, CA.
95131
(408) 262·1100
Publication PIN
81·40184

PREFACE
This manual describes the electrical and
mechanical characteristics of the Q2000
Series Rigid Disk Drive required by
customers
who purchase it as an. OEM
device. It contains timing, electrical and
mechanical specifications, and recommend-
ed
circuitry necessary to interface it to a
host
controller and data separator.

TABLE OF CONTENTS
1.0 Introduction .......... '. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 General Description . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 1
1.2 Specification Summary . .. . . . . .. . . . . .. . . . .. .... . .. . . . 2
1.2.1 Physical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.2 ReliabilitySpecifications ............................ 3
1.2.3 Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.4 Functional Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.0 Functional Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 General Qperatlons ................................. 5
2.2 Read/Write and Control Electronics. . . . . . . . . . . . . . . . . . . . 5
2.2.1 Transducer PCB ........... . . . . . . . . •. . . . . . . . . . . . . . . . 5
2.2.2 Main PCB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3 Drive Mechanism ................................... 6
2.4 Read/Write Heads and Disks ......................... 6
2.5 Head Positioning System ............................ 6
2.5.1 Rotary Torque MotorActuator .................•...... 6
2.5.2 OpticalTrack Position Encoder ....................... 6
2.5.3 Temperature Compensation Servo. . . . . . . . . . . . . . . . . . . . . 6
2.6 Air Filtration System ................................ 8
3.0 Functional Operations. . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1 Power Sequencing .. . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2 Drive Selection .........•.................... . . . . . . . 9
3.3 Track Accessing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.4 Head Selection. . . . . . .. . . . . . . . . . . . . . . ... . . . . . . . . . . . . 10
3.5 Read Operation. . . .. . .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 10
3.6 Write Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.0 Interface Lines and Pin Assignments. . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.0 Signal Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1 Control Input Lines.. . . . .. . . . . . . . . . . . .... . •. . . .. . . . . . 11
5.1.1 Drive Select 1through 4 . . . .. . . . .. . . .. . . . . . . . . . .. . . . . . 11
5.1.2 Direction In ......... . . . . . .. . . . . . . . . .. . . . . . .. . . . . . . . 12
5.1.3 Step.. . . . . . .. . . . .. . . . . .. . . . . ... .. . . ... . . . . . .. .. . . . 12
5.1.3.1 Normal Step Mode ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1.3.2 Buffered Step Mode................................. 12
5.1.4 Head Select 2°, 21, and 22 . . . . . . . .. . . . . ... ... . . . . . . . . . . 12
5.1.5 Write Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 18
5.1.6 Reduced Write Current. . . . . . .. . .. .. . . . . . . . . . . . . . . . .. . 18
5.1.7 Rezero.. .. .. . . .. . .. . . . . . . . .. . .. . . . . . . . . . . . . . .. . . . . 18
5.2 Output Lines. .... . .. . .... . . . . . . . .... . . . .. . . . . ... . . . 18
5.2.1 Track 000 . .. . . . . . ... . .. . . . . . . . . . . . . . . . . . . . . . .. . . .. . 19
5.2.2 Index. . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . .. . . 19
5.2.3 Ready . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . 19
5.2.4 Write Fault. .. . ...... . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . 19
5.2.5 Seek Complete .... . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 19
5.3 Data Transfer Lines .............. . . . . . . . . . . . . . . . . . . . 20'
5.3.1 MFM Write Date.................................... 20
5.3.3 Timing Clock. . . . . .. •. . . . . . . . •. . . . . . . . . . . . .. . . . . . . . . 20
5.4 Select Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
II

6.0 General Timing Requirements ..........•.................... 23
7.0 Power Interface. . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . 25
7.1 AC Power ................. ~........................ 25
7.2 DC Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.0 Physical Outline . . . . . . .. .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 27
9.0 Physical Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 27
9.1 J1/P1 Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9.2 J2/P2 Connector. . . . . . . . . . . . . . . . . . . . . . . .. .. . .. . . . . . . 29
9.3 J5/P5 Connector. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 29
9.4 J4/P4Connector. .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 29
10.0 Q2000 Recommended Track Format. . . . .. . . . ... .. . . . . . . . . . . . . 31
10.1 Gap Length Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
10.1.1 Gap 1 ............................................. 32
10.1.1 Gap2............................................. 32
10.1.3 G·ap 3 ............................................. 32
10.1.4 Gap 4 ..............................•.............. 32
10.2 Write Precompensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
11.0 Installation Instruction ..................................... 35
11.1 Required Tools.. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 35
11.2 Unpacking Instructions. . . . . . . . .. . . . . ... . . . . . . . . . . . . . 35
11.3 MotorLocking Clip Disengagement. . . . . . . . . . . . . . . . . . . . 35
11.4 Actuator Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
11.5 Drive Options ...................................... 36
11.5.1 JumperOptions (Main PCB) .......................... 36
11.5.2 Cut Trace Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
11.6 Control LineTermination. . . . . . . . . . . . . . . .. . . . . . . . . . . . . 36
12.0 Shipping Instructions ........ ~ . . . . . . . .. . . . . . . . . . . .. . . .. . . . . . 36
12.1 Actuator Lock. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 36
12.1 Motor Locking Clip Engagement. . . . . . . . . . . . . . . . . . . . .. .36
12.3 Packaging ................ '. . . . . . . . . . . . . . . . . . . . . . . . . ~6
Appendix A - Definition of Terms. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 39
Appendix B- Media Defectsand Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Appendix C - Ordering Information ................................ 45
iii

Figure
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
fA
IB
"
III
IV
V
VI
VII
VIII
IX
X
XI
LIST OF ILLUSTRATIONS
Q2000 Series Rigid Disk Drive .............................. .
Servo Information Location ................................ .
Head Positioning Mechanism
.............................. .
Air Filtration System
...................................... .
Typical Multiple Drive Connection
.......................... .
Normal Step Mode Timing
................................. .
Buffered Step Mode Timing
................................ .
Control Signal Driver/Receiver Combination
.................. .
IndexTiming ............................................. .
DataTransfer Line Driver/Receiver
.......................... .
MFM Write Data Timing
................................... .
MFM Read DataTiming
................................... .
General Control Timing Reqirements
........................ .
Q2000 Mounting Dimensions ............................... .
Mechanical Dimensions and Connector Location
............. .
J1 ConnectorDimensions ................................. .
J2 ConnectorDimensions
................................. .
J5 Connector
............................................ .
J4 Connector
............................................ .
Track Format
............................................ .
Motor Locking Clip Location ............................... .
Actuator Lock ............................................ .
PCB Jumper Locations .................................... .
Typical Quantum Disk Drive Organization and Terminology
..... .
Data Area and Landing Zone
............................... .
LIST OF TABLES
JlIP1 Connector Pin Assignment ........................... .
J2/P2 ConnectorPin Assignment
........................... .
P5·DC ConnectorPin Assignment ........................... .
P4·AC Connector Pin Assignment ........................... .
Interface and Power Connections ........................... .
J2 InterfaceConnection
................................... .
Head Select Decode
...................................... .
AC Power Requirements ................................... .
DC Power Requirements ................................... .
Write Precompensation
................................... .
Product Selection Index
.................................•..
Voltage and Frequency Conversion Information ............... .
v
6
7
8
13
13
15
18
19
20
20
21
23
27
28
29
29
29
29
32
35
35
37
41
41
14
14
15
15
16
17
18
25
26
33
45
45
iv

Quantum's new Q2000 8-inch fixed disk drive compatible with industry standard
Shugart Associates SA1000.
Figure 1. Q2000 Series Rigid Disk Drive
v

1.0 INTRODUCTION
1.1 General Description
The Quantum Series 2000 Disk Drive is a
random access storage device
with one, two,
three, or
four non-removable 8" rigid disks
as storage media. Each disk surface employs
one movable head
to access the 512 data
tracks. The
four models of the Q2000 series
are Q2010, Q2020. Q2030, and Q2040
with
one, two, three, or four disk platters respec-
tively. The Q2010 provides 10.66 megabytes
of storage accessed by 2 movable heads.
The Q2020 had 21.33 megabyte capacity,
the Q2030
has 32.00 megabyte capacity and
the Q2040
has 42.67 megabyte capacity with
4, 6 and 8 movable heads respectively. Low
cost and drive
reliability are achieved
through the
use of a unique positioning ac-
tuator design. The inherent simplicity of
mechanical construction and electronic con-
trol allows operation with minimal
maintenance throughout the life of the
drive.
Mechanical and contamination
protection
for the heads, actuator, and disks is provid-
ed by
an impact resistant plastic and
aluminum enclosure. A self-contained recir-
culation system supplies clean air through a
0.3 micron filter with another absolute filter
allowing pressure equalization with ambient
air
without contamination.
The Q2000
Series Disk Drive is also supplied
with an actuator lock and a spindle lock for
shipping protection. In addition, the heads
are positioned in a landing and shipping
zone on the disk surfaces which is inside
track
511. The heads are always positioned
in this zone when power
is removed so that
the heads never rest upon any area of the
disk surface where data
is written. Upon
power up, the heads
do not move from this
area
until the disk is rotating fast enough
for the heads to fly.
An external data separator
is required to
provide MFM encoding/decoding, write
precompensation, a crystal controlled
write
oscillator, and address mark writing and
detecting. Quantum's Q2200 data separator.
may
be used for these fUnctions. Most con-
trollers, however, integrate these functions
into the
controller design. The Q2000 fixed
disk drive interface
is similar to the Shugart
1

8" floppy drive and a superset of Shugart's
SA1000 series disk drive interface. The
Q2000 series disk drive is designed with the
same
form factor and power supply voltage
requirements
as 8" floppy drives.
Key Features:
• Storage Capacity
of 10, 20, 30, or 40
megabytes
• Winchester design
reliability
• Same physical size and mounting
as
8" floppy drives
•
Uses the same D.C. voltages as
8" floppy and SA1000 drives
0 Proprietary, rotary, high resolution,
quiet, head-position actuator
• 4.34M bits/second transfer rate
• Shugart SA1000 interface compatible
• Microprocessor controlled temperature
compensation servo
1.2 SPECIFICATION SUMMARY
1.2.1 Physical Specifications
ENVIRONMENTAL LIMITS
2
Ambient temperature
= 50° to 115°F (10° to 46°C)
Relative Humidity
= 8% to 80%
Maximum wet bulb
= 78° non-condensing
AC POWER REQUIREMENTS
SO/60Hz
±0.5Hz
100/115VAC Installations =
90-127V at 1.0A Typical
200/230VAC Installations =
180-253V at O.5A Typical
DC VOLTAGE REQUIREMENTS
+24VDC±10% 1.25A Typical
+ 5VDC ± 5% 1.01 Typical
-5VDC±5% (-7 to -16VDC
optional) O.2A Typical
MECHANICAL DIMENSIONS
Height = 4.50 in.
(114.3mm)
Width = 8.55 in.
(217.2mm)
Depth = 14.25 in.
(362.0mm)
Weight = 17 Ibs.
(7.7Kg)
HEAT DISSIPATION
= 235 BTU/HR. TYP (70 Watts)

1.2.2 Reliability Specification
MTBF: 8,000 POH typical usage
PM: not required
MTTR:
30 minutes
Component life: 5 years
Error Rates
Soft read errors: 1 per 10
10
bits read
Hard read errors: 1 pet 1012 bits read
Seek errors: 1 per 106 seeks
1.2.3 Performance specifications
Q2010
Capacity
Unformated
Per drive
Per surface
Per track
Formatted (MFM)
Per drive
Per surface
Per track
Per sector
Sectors/TK
Transfer Rate
Access Time
TK to TK
Average
Maximum
Avg. Latency
10.66Mb
5.33Mb
10.40Kb
8.4OMb
4.20Mb
8.20Kb
256 Bytes
32
4.34Mbits/sec
15
ms
50 ms
100 ms
10 ms
1.2.3 Functional Specifications
Rotational speed 3000 RPM
Recording Density
6600 bpi
Flux Density
6600 fci
Track Density
345 tpi
Cylinders 512
Tracks 1024
R/W Heads 2
Disks 1
Index 1
Q2020
21.33Mb
5.33Mb
10.4OKb
16.80Mb
4.20Mb
8.20Kb
256 Bytes
32
4.34Mbits/sec
15
ms
55 ms
100 ms
10 ms
3000 RPM
6600 bpi
6600 fci
345 tpi
512
2048
4
2
1
Rotational speed, recording, flux and track
densities
differ from SA1000 values to ac-
comodate Quantum track position servo
and higher disk capacity while retaining
Shugart Associates
SA1000 and SA1400 for-
mat and interface compatibility.
Q2030
32.00Mb
5.33Mb
10.40Kb
25.20Mb
4.20Mb
8.20Kb
256 Bytes
32
4.34Mbits/sec
15
ms
60 ms
100 ms
10 ms
3000 RPM
6600 bpi
6600 fci
345 tpi
512
3072
6
3
1
Q2040
42.66Mb
5.33Mb
10.4OMb
33.60Mb
4.20Mb
8.20Mb
256 Bytes
32
4.34Mbits/sec
15
ms
65 ms
100 ms
10 ms
3000 RPM
6600 bpi
6600 fci
345 tpi
512
4096
8
4
1
3

2.0 FUNCTIONAL CHARACTERISTICS
2.1 General Operation
The Series 2000 fixed disk drive consists of
read/write and control electronics, read/
write heads, head positioning mechanism,
media, and air
filteration system. These
components perform the
following func-
tions:
• Interpret and generate control signals
• Position the heads over the selected
track
with appropriate corrections to
compensate for thermal effects on
track location
• Read and write data
• Provide a contamination free environ-
ment around the media
• Perform diagnostics on the head posi-
tioning and servo systems
2.2 Read/Write And Control Electronics
The electronics for the drive are packaged
on
two printed circuit boards, the control
PCB and the Transducer PCB.
2.2.1 Transducer PCB
The Transducer PCB contains the following
circuits:
• Coarse servo transducer detector
circuit
• Raw track 0 detector circuit
• AGC circuit for servo and track 0
sensors
• Head select diode matrix
2.2.2 Control PCB
The main PCB contains the following
circuits:
• Index detector circuit
• Head positioning actuator predrivers
• Microprocessor for diagnostics and fine
servo control
as well as step buffers.
• Read/write amplifier/drivers
• Head select circuits
• Drive select circuit
5

• Drive ready
circuit
• Write fault detection circuit
• Power on reset circuit
• Track 0 indicator circuit
2.3 Drive Mechanism
The spindle rotates at 3000 rpm through a
belt drive from an AC motor. Either 50 or
60Hz power is accomodated by changing
the
motor drive pulley and belt. 220/230VAC
operation can be utilized by a motor
change.
2.4 Read/Write Head And Disks
The recording media is a lubricated thin
magnetic oxide coated on an 8 inch
diameter aluminum substrate. This
lubricated coating formulation, together
with the low load force/low mass Win-
chester type
flying heads permit reliable
contact start/stop operation.
2.5 Head Positioning System
The head positioning system consists of
three major elements: rotary torque motor
actuator, optical track position encoder, and
temperature compensation servo.
2.5.1 Rotary Torque Motor
Actuator (Fig. 3)
The read/white heads are mounted on
counterbalanced arms attached
to the hub
of the roatry torque motor. This configura-
tion applies a pure torque to the rotor. The
balance system maximizes bearing
life and
leads
to high mechanical stability and max-
imum vibration resistance.
The
motor is of simple construction con-
sisting
of a ring magnet, two flat plate pole
pieces, a single plane moving coil and
two
bearings. This system is faster than stepper
motors and its performance matches many
voice
coil actuator systems.
6
2.5.2 Optical Track Position Encoder
The optical track position encoder is a pro-
ven technology
utilizing a highly reliable
photo etched scale, an LED light source and
photodiode sensors. The encoder com-
ponents are located inside the bubble
with
the scale attached to the lowermost ac-
tuator arm. This system is accurate to over
ten times the track density
utilized in this
product.
2.5.3 Temperature Compensation Servo
The temperature compensation, (fine) servo
obtains position feedback
directly from the
disk surface
50 times each second. This
track location coding
is embedded between
the last inter-record gap and the index pulse.
This information
is transparent to the con-
troller or host since writing is inhibited by
the drive during this servo operation. Com-
patibility is maintained with like drives by
reducing the disk rotational speed by 4%.
This servo method places no restrictions on
format and allows platter capacities equal
to other comparable competitive units.
PHYSICAL
INDEX
SERVO
INFORMATION
INDEX TO
INTERFACE
Figure 2. Servo Information Location

OPTICAL TRANSDUCER
TRANSDUCER
PCB
COUNTERBALANCE
ACTUATOR
ARM
HEAD
ROTOR COIL
(2 PHASE)
BonOM POLE
PIECE
TOP POLE
PIECE
CRASH STOP
Figure 3. Head Positioning Mechanism
7

2.8 Air Filtration System
(Fig. 4)
The disk(s) and read/write heads are fully
enclosed in a module consisting of a casting
and a plastic bubble. The
module uses an
integral recirculatory air system with an ab-
solute (0.3 micron)
filter to maintain a clean
environment. A separate absolute
filter is
mounted in the bubble at the lowest
pressure area in the system to allow
pressure equalization with the ambient air
without contamination.
Figure 4. Air Filtration System
8
BREATHER
FILTER
RECIRCULATION
FILTER

3.0 FUNCTIONAL OPERATIONS
3.1 Power Sequencing
No power sequencing is necessary with the
Q2000 series drive. Upon power up, seeking
is inhibited until the disk is at 90% of its
normal rotational speed. Upon attaining
90% of the normal speed the READY signal
will be presented to the controller interface
and the drive will initiate a recalibrate se-
quence. The recalibrate sequence is:
1. Seek to track O.
2. Seek to track 508.
3. Determine the offset value and store it
in memory.
4. Repeat steps 2 and 3 for tracks 509,
510, and 511.
5. Seek to track 448.
6. . Determine the difference between the
offset required and the offset deter-
mined
for track 508. Store this
difference value in memory.
7. Repeat steps 5 and 6 for tracks 384,
320,256,192,128,64, and O.
This procedure has established eight zones,
each with its own thermal compensation
value.
These values will be updated with each
revolution
of the disk thereby providing real
time tracking and adjustment for thermal
drift. The initial recalibrate sequence takes
approximately 3 seconds
to complete and
"SEEK COMPLETE" will be false during
this time.
3.2 Drive Selection
Drive selection occurs when one of the 4
drive select lines is activated. Only the drive
appropriately jumpered will respond to in-
put signals and gate output signals to the
controller.
3.3 Track Acce •• lng
Read/write head positioning is accomplished
by:
a) Deactivating write gate
b) Activating the appropriate drive select
line
9

c) Assuring that the drive is ready and
seek
complete is true by checking the
ready and seek
complete lines
d) Select the appropriate direction
e) Pulse the step line
Stepping can occur in either the normal or
buffered modes. In the normal stepping
mode, the heads are repositioned at the rate
of the incoming step pulses. In the buffered
step mode, incoming step pulses are
buffer-
ed in the microprocessor. When all of the
steps have been received,
they are issued at
a ramped stepping rate to the actuator
motor.
Each pulse
will cause the heads to move
one track position in
or out depending on
the level
of the direction in line. A true
level on this line will cause steps to be in-
ward while a false level will cause steps out-
ward toward track o.
3.4 Head Selection
Any of the 8 possible heads may be selected
by placing that head's appropriate binary
address on the 3 head select lines.
3.5 Read Operation
Reading data from the Q2000 drive is
accomplished by:
a) Deactivating the write gate signal
b) Activating the appropriate drive select
line
c) Assuring that the drive is ready by
checking the ready line
d) Selecting the appropriate head
3.6 Write Operation
Writing data onto the disk is accomplished
by:
a) Activating the appropriate drive select
line
b) Assuring that the drive is ready by
checking the ready line.
c) Clearing any Write Fault conditions if
they exist by reselecting the drive
d) Selecting the appropriate head
e) Activating Write Gate and placing
MFM data on the Write Data line
10

4.0 INTERFACE LINES AND PIN
ASSIGNMENTS
The interface of the drive is divided into
three categories: Signal, DC power, and AC
power. Tables I, II and III define the pin
assignments
for these interface lines. Tables
IV and V show the recommended cable
types and the grounding configurations
at
the drive and at the host systems. Signal
pins marked
SPARE are uncommitted. Those
signal pins marked
NA should not be used
as alternate I/O signal pins if a controller
having a floppy disk interface is used. A
4-drive subsystem
is shown in Figure 5.
5.0 SIGNAL INTERFACE
The signal interface consists of two
categories: Control, and data transfer. All
control lines are TTL in nature and either
provide signals
to the drive (input) or pro-
vide signals to the host (output) via interface
connector J1/P1. The
data transfer signals
are differential in nature. They provide data
and clocking, either to or from the drive, via
the J2/P2 Connector.
5.1 Control Input Lines
The control input signals are of two types:
Those intended
to be multiplexed in a multi-
ple drive system and those intended to do
the multiplexing. The control input signals
to be multiplexed are STEP, DIRECTION,
HEAD SELECT 2°, 21 and 22, WRITE GATE,
REDUCED WRITE CURRENT, and REZERO.
The signal which
is intended to do the
multiplexing is DRIVE SE LECT 1, DRIVE
SELECT 2, DRIVE SELECT 3, or DRIVE
SELECT 4.
The input lines have the following electrical
specifications. Refer to figure 6 for the
recommended circuit.
Logic
"0" = True = O.OV DC to 0.04V DC
@ lin = 40 MA (max)
Logic
"1" = False = 2.5V DC to 5.25V DC
@ lin = 0 MA (Open)
5.1.1 Drive Select 1 thru4
DRIVE SELECT when true logically connects
the drive
to the control lines. Only one
DRIVE SELECT line may be active at a time
and will allow the drive to respond to input
signals and gate outputs.
11

5.1.2 Direction In
This signal defines direction of motion of
the R/W heads when the STEP line is pulsed.
An open
circuit or logical one defines the
direction as "out" and if a pulse is applied
to the STEP line the R/W heads wi" move
away
from the center of the disk.
Conversely,
if this input is shorted to ground
or a logical zero level is applied, the direc-
tion of motion is defined as "in" and if a
pulse
is applied to the STEP line, the R/W
heads
wi" move toward the center of the
disk. A 220/330 ohm resistor pack allows
line termination.
5.1.3 Step
This interface line is a control signal which
causes the R/W head to move with the
direction of motion defined by the DIREC-
TION IN line.
The access
motion is initiated at each
logical zero to logical one transition on the
trailing edge of this signal pulse. Any
change in the DIRECTION IN line must be
made
at least 100ms before the leading
edge
of the step pulse.
There are
two modes of operaion of step-
ping the R/W heads, the normal mode and
the buffered mode.
5.1.3.1 Normal Step Mode
In this mode of operation the R/W heads
wi" move at the rate of the incoming step
pulses. The
minimum time between suc-
cessive steps is 1.0ms. The minimum pulse
width is 3.0us. See Figure 6 for normal step
mode timing.
5.1.3.2 Buffered Step Mode
In this mode of operation the step pulses
are received
at a high rate and buffered into
a counter. After the last pulse the R/W
heads
wi" then begin stepping the ap-
propriate number of cylinders and Seek
Complete (see section 4.2.5) will go true
after the
R/W heads settle at the cylinder.
This mode
of operation is automatically
selected when the time between step pulses
is < 200 usec.
12
100ns after the last step pulse has been sent
to the drive, the DRIVE SElECT line many
be dropped and a
different drive selected.
The
minimum time between steps is 3.0us
with a pulse witdth of 3.0us minimum. The
maximum time between steps is 200us.
Refer to Figure 6 for Buffered Step Mode
Timing.
Note: 1. Step pulses
with periods between
200us and 1.0 ms are not allowed.
Seek accuracy is not guaranteed
if this restriction is violated.
2. A 220/330 ohm resistor pack
allows step line termination.
5.1.4 Head Select 2°, 2\ & 22
These three lines provide for the selection
of each individual read/write heads in a
binary coded sequence. HEAD SElECT
2° is
the least significant line. Heads are
numbered 0 thru
7. When a" HEAD SElECT
lines are false, head 0
wi" be selected.
TAble VI shows the HEAD SElECT decode
and model variations
for the HEAD ,SElECT
lines. See Figure 11 for timing considera-
tions.
A 220/230 ohm resistor pack allows
for ter-
mination on each line.