Shugart SA1000 User manual

TABLE OF CONTENTS
1.0 Introduction ..................................................................... .
1.1 General Description .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
1.2 Specification Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 2
1.2.1 Physical Specifications ................................ . . . . . . . . . . . . . . . . . . . . . . . .. 2
1.2.2 Reliability Specifications
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2
1.2.3 Performance Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 3
1.2.4 Functional Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 3
2.0 Functional Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 4
2.1 General Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
2.2 Read/Write and Control Electronics
........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
2.3 Drive Mechanism
..................................................... : . . . . . . . .. 5
2.4 Air Filtration System (Figure
1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
2.5 Positioning Mechanism (Figure
2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
2.6 Read/Write Heads and Disk(s). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 5
3.0 Functional Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
3.1 Power Sequencing .............................................................. 7
3.2 Drive Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. . . . . . . . . . . . . . . .. 7
3.3 Track Accessing
................................ '. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
3.4 Head Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 7
3.5
Read Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
3.6 Write Operation
........................................... '. . . . . . . . . . . . . . . . . . . . .. 8
4.0 Electrical Interface .
J. . . . . . . . . . • • • • . • . . . • • . • . • • • • . . • . . . . • • • . . . . . . . . • • . . . . . . . • • . . . • • .. 8
4.1 Signal Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8
4.1.1 Control Input Lines ..................................................... " ....... 10
4.1.1.1
DriveSelect1-4 ............................................................. 10
4.1.1.2 Direction
In ................................................................. 10
4.1.1.3 Step
....................................................................... 11
4.1 .1.4 Head Select 2° and 21 ......................................................... 12
4.1.1.5 Write Gate
... , .............................................................. 12
4.1.1.6 Reduced Write Current
........................................................ 12
4.1.2 Control Output Lines
............................................................ 13
4.1.2.1 Track 000
................................................................... 13
4.1.2.2 Index
...................................................................... 13
4.1.2.3 Ready
............................................................ 13
4.1.2.4 Write Fault. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
....... 14
4.1.2.5 Seek Complete
.............................................................. 14
4.1.3 Data Transfer Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
...... 14
4.1.3.1 MFM Write Data
...... ' ....................................................... 15
4.1.3.2 MFM Read Data
............................................................. 15
4.1.3.3 Timing Clock
................................................................ 16
4.1.4 Select Status
................................................................. 16
4.1.5 General Timing Requirements
.................................................... 17
4.2 Power Interface
................................................................. 17
4.2.1 AC Power .................................................................... 17
4.2.2 DC Power .................................................................... 17
5.0 Physical Interface
.................................................................. 19
5.1 J1/P1 Connector ................................................................ 20
5.2 J2/P2 Connector
................................................................ 20
5.3 J4/P4 Connector
........................................................... 21
5.4 J5/P5 Connector .......................................................... 21

6.0 Physical Specifications ................. .
7.0 Media Defect and Errors .......... .
8.0 SA1 000 Track Format ...... .
8.1 Gap Length Calculations ....... .
8.1.1 Gap 1 ...... .
8.1.2 Gap 2
...... .
8.1.3 Gap 3
...... .
8.1.4 Gap 4
8.2 Write Precompensation
.. ........ . ....... .
9.0 SA 1000Jumper Options . . . . . . . .. . ......... .
10.0 SA1 000 Unpackaging Instructions. . .. . ........ .
LIST OF ILLUSTRATIONS
. . . . . . . . . . . . . . . . . 22
. . . . . . . .. '" 24
. ............. 25
..... 25
.
...... 25
.
...... 25
. ....... 25
25
.
......... 26
27
28
Figure 1. Air Filtration System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
2. Positioning Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6
3. J1 Interface and Power Connection ............................ ................ 9
4. Control Input Driver/Receiver Combination ....................................... 10
5. Normal Step Mo'de .......................................................... 11
6. Buffered Step Mode .......................................................... 11
7. Head Selection Timing ....................................................... 12
8. Control Output Driver/ReceiverCombination ................ , ..................... 13
9. Index Timing ............................................................... 13
10. Data Transfer Line Driver/ReceiverCombination ................................... 14
11. J2 Interface Connection ...................................................... 15
12. MFM Read/Write Data Timing .................................................. 15
13. General Control Timing Requirement ............................................ 16
14. Connector Locations ......................................................... 19
15. J1 Connector Dimensions ..................................................... 20
16. J2 Connector Dimensions ..................................................... 20
17. J4 Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................. 21
18. J5 Connector ............................................................... 21
19. Rack Mount Physical Dimensions ............................................... 22
20. Standard Mount Physical Dimensions ............................................ 23
21. Track Format ............................................................... 26
22. SA1000Controi PCB .................................................... : .... 27
23. SA1000Packaging .......................................................... 28
TABLES
1. Head Select ................................................................. 12
2. AC Power Requirements ....................................................... 18
3. DC Requirements ., .......................................................... 18
4. Write Precompensation ........................................................ 26

1.0 INTRODUCTION
1.1 GENERAL DESCRIPTION
The Shugart Model 1000 series disk drive IS a random access storage device with one or two non-removable
8" disks as storage media. Each disk surface employs one movable head to service 256 data tracks. The
two models of the SA1 000 series are the 1002 and the 1004 with single and double platters respectively. The
SA1002 provides 5 megabytes accessed by 2 movable heads and the SA1004 provides 10 megabytes ac-
cessed by 4 movable heads.
Low cost and unit reliability are achieved through the use
of a unique band actuator design. The inherent
simplicity of mechanical construction and electronic controls allows maintenance free operation throughout
the life of the drive.
Mechanical and contamination protection for the head, actuator and disks are provided bv
an impact resis-
tant plastic and aluminum enclosure. A self contained recirculatin'g system supplies clean air through a 0.3
micron filter. Another absolute filter allows pressure equalization with ambient air.
The optional
SA 1200 Data Separator PCB or equivalent circuitry is necessary to provide MFM en-
coding/decoding, write precompensation, a crystal write oscillator and address mark writing and detection.
These functions are also provided by the optional
SA 1400 controller.
The
SA 1000 fixed disk drive's interface is similar* to the Shugart 8" family of floppy disk drives. The SA1000
is designed to fit into the same physical space as the 8" floppies.
Key Features:
• Storage Capacity of 5.33 or 10.67megabytes.
• Winchester design reliability.
• Same physical size and identical mounting configuration as the SABOO/B50 floppies.
• Uses the same D.C. voltages as the SA800/850 floppies.
• Proprietary Fas Flex III band actuator.
• 4.34 Mbits/second transfer rate.
• Simple floppy like interface.
*Existing floppy controllers are not compatible with the
SA 1000 due to differences in the data transfer rates.
1

1.2 Specification Summary
1.2.1 Physical Specifications
Envi ron mental Limits
Ambient Temperature =
Relative Humidity=
Maximum Wet Bulb=
AC Power Requirements
50/60 Hz ± O.5Hz
100/115 VAC Installations
200/230
VAC Installations
DC Voltage Requirements
50° to 115°F (10° to 46°C)
BO/o to BO%
7Bo non-condensing
=90-127V at 1.1 A typical
= 1 BO-253V at 0.6A typical
+24VDC ± 10% 2.BA typical during stepping
(O.2A typical steady state, non stepping)
+5VDC ± 5% 2.OA typical during stepping (3.6A
typical non-stepping)
-5VDC±5
%
(-7 to -16VDC optional) 0.2A typical
Mechanical Dimensions
Height =
Width =
Depth =
Weight =
Rack Mount
4.62
in. (117.3mm)
8.55
in. (217.2mm)
14.25
in. (362.0mm)
Standard Mount
4.62 in. (117.3mm)
9.50 in. (241.3mm)
14.25 in. (362.0mm)
17
Ibs. (7. 7Kg) 17 Ibs. (7.7Kg)
Heat Dissipation =150 Watts
(511 STU/Hr) Max.
1.2.2 Reliability Specifications
MTBF: B,OOO POH typical usage
PM: None Required
MTTR: 30 minutes
Component Life: 5 years
Error Rates:
Soft Read Errors:
Hard Read Errors:
Seek Errors:
1 per 1010 bits read
1 per 1012 bits read
1 per 106 seeks
2

1.2.3 Performance Specifications
Capacity SA1002 SA1004
Unformatted
Per Drive 5.33 Mbytes 10.67 Mbytes
Per Surface 2.67 Mbytes 2.67 Mbytes
Per Track 10.4 Kbytes 10.4 Kbytes
Formatted
Per Drive 4.2 Mbytes 8.4 Mbytes
Per Surface
2.1 Mbytes
2.1 Mbytes
Per Track 8.2 Kbytes 8.2 Kbytes
Per Sector 256 bytes 256 bytes
SectorslTrack
32
32
Transfer Rate 4.34 Mbits/sec 4.34 Mbits/sec
Access Time
Track to Track 19 msec 19 msec
Average 70 msec
70 msec ,
Maximum 150 msec 150 msec
Average Latency 9.6 msec 9.6 msec
1.2.4 Functional Specifications
Rotational Speed 3125 rpm 3125
rpm
Recording Density 6270 bpi 6270 bpi
Flux Density 6270 fci 6270 fci
Track Density 172 tpi 172 tpi
Cylinders. 256 256
Tracks 512 1024
R/W Heads 2 4
Disks 1 2
3

2.0 FUNCTIONAL CHARACTERISTICS
2.1 GENERAL OPERATION
The SA1000 fixed disk drive consists of read/write and control electronics, read/write heads, track position-
ing mechanism, media, and air filtration system. These components perform the following functions:
1. Interpret and generate control signals.
2. Position the heads over the selected track.
3. Read and Write data.
4. Provide a contamination free environment (Class 100 or better).
2.2 READ/WRITE AND CONTROL ELECTRONICS
The standard electronics are packaged on a single printed circuit board containing the following circuits:*
1. Index Detector Ci rcuit
2. Head Position
Actuator Drivers
3. Read/Write
Amplifiers
4. Drive (Ready) up to Speed Circuit
5. Drive Select Circuit
6. Write Fault Detection Circuit
7. Read/Write Head Select Circuit
8. Step Buffers with Ramped Stepper Circuit
9. Track 000 indicator
*Early units may have two printed circuit boards.
4

2.3 Drive Mechanism
The AC drive motor rotates the spindle at 3125 RPM through a belt-drive system. Either 50 or 60 Hz power is
accommodated by changing the drive pulley and belt.
2.4 Air Filtration System (Figure 1)
The disk(s)" and read/write heads are fully enclosed in a module using an integral recirculating air system
with
an absolute filter which maintains a clean environment. A separate absolute breather filter permits
pressure equalization with the ambient air without contamination.
2.5 Positioning Mechanism (Figure 2)
The read/write heads are mounted on a ball bearing supported carriage which is positioned by the Fasflex
IIITM actuator. A stepper motor is used to precisely position the carriage assembly utilizing a unique metal
band/capstan concept.
2.6 Read/Write Heads and Disk(s)
The recording media consists of a lubricated thin magnetic oxide coating on a 200mm diameter aluminum
substrate. This coating formulation, together with the low load force/low mass Winchester type flying heads,
permit reliable contact start/stop operation.
Data on each disk surface is read by one read/write head, each of which accesses 256 tracks. The drive is
available in two basic configurations: one disk with two read/write heads, or two disks with four read/write
heads.
B~rometric
Pressure Compensation
Absolute Filter
Low Pressure
Area
Figure 1 Air Filtration System
5
Air Flow
Path
High Pressure
Area
Circulating Air
Absolute
Filter

Figure 2 Positioning Mechanism
6
Stepper Motor
Ball Bearing
Carriage Support

3.0 FUNCTIONAL OPERATIONS
3.1 POWER SEQUENCING
Since the SA1000 has a speed sense circuit'that prevents stepping until the disk is rotating at the proper
speed, no power
on sequence is required. A READY signal will be presented to the controller interface once
the disk
is up to 95% of its normal rotational speed. At READY time, after an initial power up, the drive will
recalibrate itself to
TKOOO. After a 18 msec head settle time, SEEK COMPLETE will go true. Normal seek and
read/write functions can now begin. Refer to Figure
3.
3.2 DRIVE SELECTION
Drive selection occurs when one of the Drive Select lines is activated. Only the disk appropriately jumpered
will respond to the activated Drive Select line.
3.3 TRACK ACCESSING
Read/Write Head positioning is accomplished by:
a. Deactivating Write Gate.
b. Activating the appropriate Drive Select Line.
c. Being in the READY condition with SEEK COMPLETE true.
d. Selecting the appropriate Direction.
e. Pulsing the Step Line.
Stepping can occur
at either the Normal or Buffered rate. During Normal Stepping, the heads are reposition-
ed at the rate of incoming step pulses. In the case of Buffered Stepping, incoming step pulses are received
at a high rate and are buffered into counters. When all of the steps have been received, they are issued at a
ramped stepping rate, to the stepper drivers.
Each pulse will cause the heads to move either 1 track
in or 1 track out, depending on the level of the Direc-
tion
In line. A true on the Direction In Line will cause an inward seek; a false on the Direction In Line will
result
in an outward seek toward TKOOO.
3.4 HEAD SELECTION
Any of the 4 possible heads can be selected by placing that head's binary address on the two Head Select
lines.
3.5 READ OPERATION
Reading data from the disk is accomplished by:
a. Deactivating the Write Gate Line.
b. Activating the appropriate Drive Select Line.
c. Assuring that the drive is Ready.
d. Selecting the appropriate head.
7

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.
c. Clearing any write fault conditions if they exist, by reselecting the drive.
d. Selecting the proper head.
e. Activating Write Gate and placing data on the Write Data line.
4.0 ELECTRICAL INTERFACE
The interface of the SA 1000 can be divided into three categories:
1. Signal Interface
2. DC Power
3. AC Power
The following sections provide the electrical definition for each line.
4.1 SIGNAL INTERFACE
The signal interface consists of three categories:
1. Control Input lines
2. Control Output lines
3. Data Transfer lines
All control lines are digital
in nature and either provide signals to the drive (input) or provide signals to the
disk controller (output) via the interface connector J1/P1.
The data transfer signals are differential in nature,
they provide data and clocking, either to or from the drive, via J2/P2.
NOTE: Refer to Figure 3. Those signal lines markedSPARE are uncommitted. They may be usedas alternate
lines to carry
SA 1000 signals if the user prefers to do his own modification. Those signal lines marked NA
are uncommitted for the SA1000, but are assigned for the
SASOO/SSO. Therefore, these signals should
not
be used as alternate signals if a controller having an SA800/850 interface is used.
8

DISK
1 DRIVE
CONTROLLER J1/P1
-REDUCED WRITE CURRENT., 2
..
SPARE
5
4
SPARE
7
6
--SEEK COMPLETE 9
-8
NA 10
11
NA
12
13
-HEAD SELECT 2°
...
15
-
14
NA
17
16
-HEAD SELECT 21
19
...
18
~
-
-INDEX
21
-20
--
-READY 23
22
NA 25
24
-DRIVE SELECT 1
..
27
26
~
FLAT RIBBON
OR
TWISTED PAIR -DRIVE SELECT 2
...
29
--
28
20 FT. MAX -DRIVE SELECT 3
..
31
.~
30
-DRIVE SELECT 4 33
~
32
-DIRECTION IN
35
--
34
-STEP
~
37
-36
NA 39
38
WRITE GATE
-
41
-40
--TRACK 000 43
-42
--
-WRITE FAULT 45
-44
NA 47
46
.,
NA 49
48
NA
50
+5V DC
6 LOGIC GROUND
5
~51P5
-5VDC (-7V to -16VDC OPT) 3
4 -
TWISTED
PAJR
LOGIC + 24V
DC
SINGLE
GROUND 1 WIRE
2 STRAP
--
ACINPUT
1
FRAME GROUND 2
AC MOTOR GROUND
FRAME GROUND
ACINPUT
~
-3 J4/P4
DISK CONTROLLER --SA1000 DRIVE
Figure 3 J1 Interface and Power Connection
9

4.1.1 CONTROL INPUT LINES
The control input signals are of two types: those intended to be mutliplexed in a multiple drive system and
those intended to control the multiplexing. The control input signals to be mutliplexed are
STEP, DIRECTION
IN, HEAD SELECT 20 and
21, WRITE GATE and REDUCED WRITE CURRENT. The signal which is intended to
do the multiplexing
is DRIVE SELECT 1, DRIVE SELECT 2, DRIVE SELECT 3, DRIVE SELECT 4.
The input lines have the following electrical specifications. Refer to Figure 4 for the recommended circuit.
+5 V
20ft (MAX.)
330n
Figure 4 Control Input Driver/Receiver Combination
The 7438 has the following characteristics:
True =
O.OVDC to O.4VDC @ lin =40 ma(max)
False = 2.5VDC to 5.25 VDC @ lin = 250 Ita (open)
Only 1 drive in the system should be terminated, if floppy disks are daisy chained together with SA1000
drives. A SA 1000 should be physically located at the end of the cable and terminated at IC location BC.
A 220/3300 resistor pack, located at IC location 8C, provides input line termination.
4.1.1.1 DRIVE SELECT 1·4
DRIVE SELECT, when logically true, connects the drive to the control lines. Only one DRIVE SELECT line
may be active at a time.
Jumper options
DS1, DS2, DS3, and DS4 are used to select which drive select line will activate the interface
for that unique drive.
4.1.1.2 DIRECTION IN
This signal defines the direction of motion of the read/write heads when the STEP line is pulsed. An open cir-
cuit or logical false, defines the direction as
"out" and if a pulse is applied to the STEP line, the read/write
head will move away from the center of the disk. If the input is shorted to ground, or logical true, the direction
of motion
is defined as "in" and if a pulse is applied to the STEP line, the read/write heads will move towards
the center of the disk.
10

4.1.1.3 STEP
This line causes the read/write heads to move in the direction as defined by the DIRECTION IN line. The mo-
tion is initiated at each logical true to false transition. Any change
in the DIRECTION IN line must be made at
least 200 ns before the trailing edge of the step pulse. Stepping can be performed
in either the Normal or
Buffered mode:
-STEP
~ ~ 200ns MIN.
W!!/f!!fIl/f!lI~~~rm I
~-------~~~~------------------~SS~--------
J t-3.0I's MIN. I
l j.----1.5ms MIN.~ ..... _-\~""'~ ____ _
------.U U
-DIRECTION
~
-SEEK COMPLETE
--1 ~ 500ns TYP
I 18ms
TYP ~
Sr-,~_
Figure 5 Normal Step Mode
• Normal Step Mode- In this mode, the read/write heads will move at the rate of the incoming step
pulses. The minimum time between successive steps
is 1.5ms, with a minimum pulse width of
3.0j.ts. Refer to Figure 5.
• Buffered Step Mode- In this mode, the step pulses are received at a high rate and buffered into a
counter. After the last step pulse, the read/write heads will begin stepping the desired number of
cylinders and
SEEK COMPLETE (Refer to Section 4.1.2.5) will go true after the read/write heads set-
tle on the cylinder. This mode of operation is automatically selected when the time between step
pulses is the less than 200j.tsec.
100 ns after the last step pulse has been sent to the drive, the DRIVE SELECT line may be dropped
and a different drive selected.
The maximum time between steps is
200j.ts with a minimum pulse width of 3.0j.ts. (Refer to Figure
6).
NOTE: A high pitched noise may be present if AC and DC power are applied to an SA 1000 with the
data cable disconnected (no timing clock signal). It's the stepper motor trying to return to track
zero with
no step pulses present. While this will not damage the drive, this condition should be
avoided.
-
DIRECTION
..., ~ 200ns MIN.
-----.-, -~~~~~~~ I
- STEP
~----~s~----------
- SEEK COMPLETE
J.-150ms MAX. ~
I SS I
-..t ~200ns MIN"
J SS~----
----------------------------~
--1 ~ 500ns TYP
I
- DRIVE SELECT X
Figure 6 Buffered Step Mode
NOTES: 1. Step pulses with periods between 200j.ts and 1.5ms are not permitted. Seek accuracy is not
guaranteed if this timing requirement is violated. ,
2. A 220/3300 resistor pack,located at IC location 8C, allows for Step line termination.
11

4.1.1.4 HEAD SELECT 2° and 21
These two lines rrovide for the selection of each individual read/write head in a binary coded sequence.
HEAD
SELECT 2 is the least significant line. When all HEAD SELECT lines are false, head 0 will be selected.
Table 1 shows the HEAD SELECT SEQUENCE and model variations for the HEAD SELECT lines. (Refer to
Figure 7 for the timing sequences).
A 220/330n resistor pack, located at
IC location 8C, allows for input line termination.
HEAD SELECT LINE
HEAD# SELECTED HEAD# SELECTED
2°
21
SA1002 SA1004
1 1 0 0
1 0 1 1
0 1 -2
0 0 -3
Table 1 Head Select (1 = False, 0 =True)
4.1.1.5 WRITE GATE
The active state of this signal (logical zero level) enables
WRITE DATA to be written onto the disk. The inac-
tive state of this Signal (logical one level) enables data to
be transferred from the drive and enables STEP
pulses to reposition the head arm.
HEADS SWITCHED
READ DATA
VALID
-.j ~ 20l's MAX.
~ ____ ~I I
~ ~201'S MAX.
----~I----------
~:~~~~::E ---+----------~ ....... ~ 460ns t7Ax
~:8~ CONTROLLER) ,--,L.. ________ __
Figure 7 Head Selection Timing
A 220/330n resistor pack, located at
IC location 8C, allows for termination of this line.
4.1.1.6 REDUCED WRITE CURRENT
When this interface signal
is low (true) the lower value of Write Current is selected (for writing on cylinders
128 through 255). When this Signal is high (false), the higher value of Write Current
is selected (for writing on
cylinders 0 through 127). A 220/330n resistor pack, located at Ie location 8C, allows for line termination.
12

4.1.2 CONTROL OUTPUT LINES
The control output signals are driven with an open collector output stage capable of sinking a maximum of
40 ma at logical zero (true), with a maximum voltage of
OAV measured at the driver. When the line driver is
at logical one (false) the driver transistor is off and the collector cut off current is a maximum of 250
microamperes.
All J1 output lines are enabled by their respective DRIVE SELECT line.
Figure 8 shows the recommended control signal driver/receiver combination.
+5 V
20ft (MAX.)
330n
Figure 8 Control Output Driver/Receiver Combination
4.1.2.1 TRACK 000
This interface signal indicates a true state (logical zero) only when the selected drive's read/write heads are
at track zero (the outermost data track) and the access circuitry
is driving current through phase one of the
stepper motor. This)signal
is false (logical one) when the selected drive's read/write head is not at track zero.
4.1.2.2 INDEX
The drive provides this interface signal once each revolution (19.2ms) to indicate the beginning of the track.
Normally, this signal is a logical one and makes the transition to logical zero for a period of approximately
1
OILS once each revolution. Refer to Figure 9.
INDEX
~ ________________r-1_____
1
~10I"STYP I
.. 19.2ms NOM. •
Figure 9 Index Timing
4.1.2.3 READY
This interface signal when true (logical zero), together with SEEK COMPLETE, indicates that the drive is
ready to read, write, or seek and that the signals are valid. When this line is false (logical one), all writing to
the disk and seeking
is inhibited at the drive.
Ready will
be true after the drive is 95 ± 2% up to speed. The typical time for READY to become true after
power
on is 5 seconds.
13

4.1.2.4 WRITE FAULT
This signal when active (logical zero) is used to indicate that a condition exists
at the drive that could cause
improper writing
on the disk. A WRITE FAULT occurs whenever one of two conditions occur:
• WRITE CURRENT in the head without WRITE GATE active.
• Multiple heads selected.
To reset the WRITE FAULT line, deselect the drive for at least 500 ns.
4.1.2.5 SEEK COMPLETE
SEEK COMPLETE will go true (logical zero) when the read/write heads have settled on the final track at the
completion of a seek. Reading or writing should not be attempted until
SEEK COMPLETE is true.
SEEK COMPLETE will go false in two cases:
• A recalibration sequence is initiated (by the drive logic) at power on if the read/write heads are not
over track zero.
• 500 NS typical, after the leading edge of a STEP pulse (or the first of a series of step pulses).
4.1.3 DATA TRANSFER LINES
All lines associated with the transfer of data between the drive and the host are differential
in nature and
may not
be multiplexed. These three pairs of balanced signals are: MFM WRITE DATA, MFM READ DATA,
and TIMING CLOCK and are provided at the J2/P2 connectors on all drives. Figure 10 illustrates the
driver/receiver combination.
HIGH
TRUE
FLAT CABLE
r*-_....;;.20;;.;.;ft~M;;..;;AX...;;... _. _,""*, 5Hl x 2
+SIGNAL
-SIGNAL
HIGH
>-_ TRUE
75107B
Figure 10 Data Transfer Line Driver/Receiver Combination
14

HOST -DRIVE SELECTED 2 DRIVE
..
1
--
GND
SPARE 4
:3
GND
SPARE 6
J2/P2
5
GND
SPARE 8
7
GND
+ TIMING ClK
..
9
FLAT CABLE
-TIMING ClK -
11
-10
OR TWISTED
GND
~
12
PAIR
GND
20 FT MAX +
MFM WRITE DATA
..
13
-MFM WRITE DATA -15
..
14
GND
~
16
GND
.. + MFM READ DATA
17
.: -MFM READ DATA 19
18
20
-
GND
GND
-==
-==-
--
Figure 11 J2 Interface Connection
4.1.3.1 MFM WRITE DATA
This pair of signals ,defines the transitions (bits) to be written on the disk. +MFM WRITE DATA going more
positive than -MFM WRITE DATA will cause a flux reversal on the track under the selected head providing
WRITE GATE is active. This signal must be driven to an inactive state (+ MFM WRITE DATA more negative
than -MFM WRITE DATA) by the host system when in the read mode. Figure 12 shows the timing for MFM
WRITE DATA.
4.1.3.2 MFM READ DATA
The data recovered by reading a pre-recorded track is transmitted to the host system via the differential pair
of MFM READ DATA lines. This transition of the +MFM READ DATA line going more positive than -MFM
READ DATA line represents a flux reversal on the track of the selected head while WRITE GATE is inactive.
Refer
to Figure 12.
- DRIVE SELECT
~~---------------------------------
-HEADSELEGT ---,~ ____________________________________________ __
20ILs MAX. --1 ~, -.j ~ 50ns TYP
+ MFM VALID
READ DATA
-WRITE GATE
+MFM
WRITE DATA
! -1
I I
----~I·-------2-0-IL-S-M-A-X·------·~1 Pj-----------------
460ns MAX· ....I ~ --.j ~ 50~S MIN. to 150ns MAX.
--------------------------~~----------------
BIT CELL = 230ns TYP -..J j.-
Figure 12 MFM Read/Write Data Timing
15

4.1.3.3 TIMING CLOCK
This is a differential pair of clock signals (provided by the host) having a 50
% (nominal) duty cycle and a
3.6866
p,s ± .1 % period. The frequency of this clock is exactly 1/16 the bit frequency for the standarized
write data. Phase relationship between TIMING CLOCK and MFM
WRITE DATA need not be maintained by
the host for the
SA1 000 interface. The TIMING CLOCK is used by the drive logic for clocking and timing pur-
poses.
4.1.4 SELECT STATUS
A status line is provided at the J2/P2 connector to inform the host system of the selection status of the drive.
The
DRIVE SELECTED line is driven by a TTL open collector driven as shown in Figure 8. This signal will go
active only when the drive
is programmed as drive X (X =1, 2, 3 and 4) by proper placement of the shorting
plug in the vicintiy of J1, and that DRIVE SELECT X line at J1/P1 is activated by the host system.
AC POWER ON ---1
DC POWER ON ---.J
H5SEC. TYP
-DISK 95% SPEED*_* ___ --.
-READY*
-...J ~1ms TYP
----- .... 1 -TKOOO ~. ___________________________ __
--..J I~ 5.1 SEC. MAX
-SEEK COMPLETE I
..... .....--------2 MIN. NOM.* -------i~~1
CONTROL _______________________________________ ~I~ ----
OUTPUTS VALID •
*The drive will bring Ready active as soon as the disk is rotating at 95% of normal
speed. It is now safe to seek the drive but an additional 2
minutes should be allowed for
thermal expansion to stabilize.
**Disk up to speed signal does not connect to the drive interface cable.
Figure 13 General Control Timing Requirement
16

4.1.5 GENERAL TIMING REQUIREMENTS
The timing diagram as shown in Figure 13 shows the necessary sequence of events (with associated timing
restrictions) for proper operation of the drive.
Note that a recalibrate to track zero sequence
is initiated automatically at every DC power on. For this auto-
recal sequence to function, the following conditions must be met:
• TIMING CLOCK is supplied to the drive (via J2/P2).
• STEP Input at J1/P1 is held inactive.
• Spindle is spinning at regular speed (if AC and DC are switched on at the same time, stepping ac-
tion will not occur until disk
is up to speed).
4.2 POWER INTERFACE
The SA 1000 requires both AC and DC power for operation. The AC power is used for the drive motor and the
DC power is used for the electronics and the stepper motor.
4.2.1 AC POWER
The AC power is via the connector J4 mounted at the center rear of the drive. Table 2 shows a listing of the
AC power requirements.
4.2.2 DC POWER
DC power to the _drive is via connector J5/P5 located on the solder side of the PCB. The three DC voltages
and their specifications along with their J5/P5 pin designations, are outlined in Table 3.
NOTE: The SA 1 abo is shipped with DC (base casting) and AC ground (drive motor) connected together
with a ground strap located
on the drive motor. If the system configuration requires the separa-
tion of these grounds, remove the strap.
17