Shugart SA800 Installation and operation manual

SA800/801
Diskette
Storage Drive
~ .. Shugart

TABLE OF CONTENTS
1.0 Introduction ' 1
1.1 General Description 1
1
.2 Specification Summary 2
1
.2.1 Performance Specifications 2
1.2.2 Functional Specifications 2
1.2.3 Physical Specifications 2
1.2.4 Reliability Specifications 3
2.0 Functional Characteristics 5
2.1 General Operation 5
2.2 Read/Write and Control Electronics , 5
2.3 Drive Mechanism 5
2.4 Positioning Mechanism 5
2.5 Read/Write Head 5
2.6 Recording Format 6
2.7 Optional Features 6
2.8 Model Differences 6
3.0 Functional Operations 7
3.1 Power Sequencing 7
3.2 Drive Selection 7
3.3 Track Accessing 7
3.3.1 Step Out 7
3.3.2 Step
In 7
3.4 Read Operation 7
3.5 Write Operation ,
.. , , .. , , 9
3.6 Sequence of Events ' 9
4.0
Electric~llnterface 13
4.1 Signal Interface .. , , , 13
4.1.1 Input Lines 13
4.1.1 Input Line Termination 15
4.1.1.2 Drive Select 1-4 , , 15
4.1.1.3 Direction Select , , , . , 15
4.1 .1 .4 Step ,15
4.1 .1 .5 Write Gate ,15
4.1.1.6 Write Data , . ,
.. ,16
4.1.1.7 Head Load (Alternate Input) 16
4.1.1.8
In Use (Alternate Input) .. , .. , . , , , 16
4.1.2 Output Lines 16
4.1.2.1 Track 00 , . , , ' 16
4.1.2.2 Index '.' 16
4.1 .2.3 Sector (SA801 only) '.' 17
4.1 .2.4 Ready 17
4.1 .2.5 Read Data 17
4.1 .2.6 Sep Data 17
4.1.2.7 Sep Clock 17
4.1.2.8 Write Protect (Optional on SA800) 17
4.1.2.9 Disk Change (Alternate Output) 18
4.1 .3 Alternate I/O Pins 18
4.2 Power Interface 18
4.2.1 AC Power 18
4.2.2
DC Power 19

5.0 Physical Interface :21
5.1 J1/P1 Connector :21
5.2 J5/P5 Connector :22
5.3 J4/P4 Connector :22
6.0 Drive Physical Specifications :23
6.1 Drive Dimensions :23
6.2 Mounting Recommendations :23
6.2 .. 1Vertical Mounting :23
6.2,,3 Upright Mounting " ' :23
6.3 Chassis Slide :25
6.4 Decorative Face Plate :25
7.0 Customerlnstallable Options :27
7.1 0rive Select -One to Eight Drives ................................................... :30
7.2 Select Drive Without Loading Head or Enabling Stepper Motor :31
7.3 Select Drive and Enable Stepper Without L.oading Head :32
7.4 Load Head Without Selecting Drive or Enabling Stepper :32
7.5 Radial Ready '33
7.6 Radiallndex/Sector 34
7.7Eight, 16, Or 32 Sectors 35
7.8 In Use Alternate Input (Activity LED) :36
7.9 Write Protect Optional Use 36
7.10 Disk Change (Alternate Output) ' 37
8.0 Operation Procedures 38
8.1 Diskette Loading and Handling 38
8.2 Write Protecting aDiskette . ' 39
9.0 Error Detection and Correction ' 40
9.1 Write Error 40
9.2 Read Error 40
Appendix A- Models and Features .'.' 41
ii

LIST OF ILLUSTRATIONS
Figure 1. SA800/801 Diskette Storage Drive ........................ .iv
2. SA800/801 Functional Diagram ......................... 4
3. Track Access Timing . . 8
4. Read Initiate Timing ......................... . 8
5. Read Signal Timing. ......................................... . 9
6. Write Initiate Timing. ............................... ..10
7. Write Data Timing. ........................... ........ . 10
8. General Control and Data Timing Requirements ........................ . 11
9. Interface Connections ........................................ . .. 14
10. Interface Signal Driver/Receiver ..........
.. .................... ...... .. . .... 16
11. Index
Timing. ............................................... ....... . .. 16
12. Sector Timing ............................................... .
17
13. J1 Connector Dimensions . 21
14. J5 Connector . . 22
15. J4 Connector .22
16. InterfaceConnectors-Physical Location Diagram ....................
.. . . . 22
17. Head Load Actuator Mounting Prerequisites. ....................... . .. 23
18. SA800/801 Diskette Storage Drive Dimensions
24
19. Slide Mounting Dimensions .......................................... ..25
20. SA800/801 RDimensions ................................................... 26
21. Component Locations Standard
PCB 28
22. Component Locations
LSI PCB , ,........................... . 29
23. Drive Select
Circuitry. ........................................... .. ........ ..30
24. Select
Drive Without Loading Head Circuit . . 31
25. Stepper Motor Enable Circuit. ............................. .. . . . . . . . . . . . . . . . . .. .. 32
26. Load Head Without Selecting Drive or Enabling Stepper Circuit ................. 33
27. Radial Ready
Circuit. .................................................. . ... 34
28. Radial Index/Sector Circuit. .................................... 34
29. Sector Timing Relationships. . .. ......................................... . 35
30. Sector Divide Circuit. .......................................... .
35
31. In Use/Activity LED Circuit 36
32. Write Protect Circuit. .................................................. . 36
33. Disk Change Timing .................................................... .. 37
34. Disk Change Circuit ................................................ . 37
35. Loading SA800/801 .............................. ........... . 38
36. Diskette Write Protected .39
37. Write Inhibit Notch Specifications .................................... 39
iii

SR800
Figure 1. SASOO/S01 Diskette Storage Drive
iv

1.0 INTRODUCTION
1.1 General Description
The SA800/80l are enhanced versions of the successful SA900/901 Diskette Storage Drive. The SA800/801
provides the customer with amature and reliable product, manufactured to the same high standard of ex-
cellence as the 900/901, but with additional featuress.
The SA800 Diskette Storage Drive can read and write diskettes for interchange with other SA800's, the
SA900, IBM
3741,3742 or 3540 and with the IBM System 32.
The
SA801 provides the same features as the SA800 with additional flexibility for those requirements which
preclude IBM compatibility.
The SA800/801 Diskette Storage Drives have as standard features: apatented diskette clamping/registra-
tion design which eliminates the possibility of damage to the diskette due to misregistration and quarantees
over 30,000 interchanges with each diskette; single and double density capability
on the same drive for the
same price; aproprietary ceramic
R/W head designed and manufactured by Shugart Associates to provide
media life exceeding 3.5 million passes/track and head life exceeding 15,000 hours;
an activity light which
indicates drive
in use; and ribbon cable or twisted pair connector for ease of packaging. All of these features
and more are available with
the SA800/801.
SA800/801 Diskette Storage Drive provide the system designer solutions to his applications requirements
with greater performance and reliability than cassette or cartridge drives, and lower cost with increased
function over I/O and reel-to-reel tape drives.
Applications for the SA800/801 Diskette Storage Drive are key entry systems, point of sale recording
systems, batch terminal data storage microprogram load and error logging, minicomputer program and aux-
iliary data storage, word processing systems and data storage for small business systems.
The SA100 Diskette, IBM Diskette or equivalent, can
be read and written interchangeably between any
SA800 and IBM 3741/42, 3747 and 3540. The
SA 101 Diskette can be read or written interchangeably on any
SA801. The
SA 102 and SA 103 are used for double density applications.
As a product enhancement, to improve reliability and serviceability, Shugart is incorporating into the SABOO
serves drives a PCB Large Scale Integration (LSI) components. These components are:
•Control Chip
•Write Channel
•Read Channel
The LSI Control chip performs the following functions:
•
TRK 00 detector
•Index detector
•Stepper logic
•FM clock/data separator and data window
•Sector separator
•Write Protect
detector
•Door open/close detector
•Disk change circuit
•Ready signal
The functions listed above are either detected from the drive mechanics or from the Host Interface. As a
result, the proper logic generated by the LSI chip either will be used within the drive electronic circuit to per-
form stepping, read/write operations
or will be fed back to the Host Interface.
Also, an internal FM data separator is incorporated inside the chip. A
jumper option will allow the user to
select the data separator to perform as its predecessor SABOO (jumper FS) or to select the separator to be
compatible with the IBM System 3740 data separator(jumper
TS). Thus IBM compatibility will allowdirect in-
terfacing with LSI single chip floppy disk controllers.

1.2 Specification Summary
1.2.1 Performance Specifications
Capacity
Unformatted
Per Disk
Per Track
IBM Format
Per Disk
Per
Track
Tranfer Rate
Latency (average)
Access Time
Track to Track
Average
Settling Time
Head Load Time
Single Density
3.2 megabits
41 .7 kilobits
2.0 megabits
26.6 kilobits
250 kilobits/sec.
83
ms
8 ms
260·ms
8 ms
35 ms
Double Density
6.4 megabits
83.4 kilobits
n/a
n/a
500 kilobits/sec
83
ms
8 ms
260 ms
8 ms
35 ms
1.2.2 Functional Specifications
Rotational Speed
Recording Density
(inside track)
Flux Density
Track Density
Tracks
Physical Sectors
SA800
SA801
Index
Encoding Method
Media Requirements
SA800
SA801
1.2.3 Physical Specifications
Single Density
360 rpm
3200 bpi
6400 fci
48 tpi
77
o
32/16/8
1
FM
SA100IIBM Diskette
SA101
Double Density
360 rpm
6400 bpi
6400 fci
48 tpi
77
o
32/16/8
1
MFM/M
2FM
SA10211BM Diskette
SA103 .
Operating
=40°F to 115°F (4.4° to 46.1 DC)
= 20% to 80%
=78°F (25°C) .
Enviromental Limits
Ambient Temperature
Relative
Humidity
Maximum Wet Bulb
AC Power Requirements
50/60 Hz ±0.5 Hz
100/115 VAC Installations =85 to 127V @.3A typical
200/230 VAC Installations =170 to 253V @.18A typical
DC Voltage Requirements
+ :24 VDC ± 5% 1.3A typical
+5VDC ± 5% 0.8A typical
t -5 VDC ±5
%.05A typical (option
-7 to -16 VDC)
Mechanical Dimensions (Reference Figures 18 and 20)
Width = 4 5/8 in. (11.75 cm)
Height - 9 1/2 in. (24.13 cm)
Depth -- 14 1/4 in. (36.20 cm)
Weight =13.0 Ibs. (5.91 kg)
Heat Dissipation =
271 BTU/hr. typical (80 Watts)
tMinus voltages are not required .tor SA800L.
2
Shipping
-40°F to 144°F
1to
95%
No Condensation
Storage
-BoF to 117°F
1to 95%
No Condensation

1.2.4 Reliability Specifications
MTBF:
PM:
MTTR:
Component Ufe:
Error Rates:
Soft
Read Errors:
Hard Read Errors:
Seek Errors:
Media Ufe:
Passes Per Track
Insertions:
5000
POH under heavy usage
8000
POH under typical usage
Every 5000
POH under heavy usage
Every 15,000 under typical usage
30 minutes
15,000 POH
1per 109bits read
1per 1012 bits read
1per 106seeks.
3.5 X106
30,000 +
3

V'JR!TE PROTECT LED
WRITE PROTECT DETECTOR
INDEX
DETECTOR
___ ~I
~~
,,~
L.-a ---- "~, l ~
'~~/
/"~~
"~
~~
I"
READ HEADI
I
I
I
I
I
I
I
INDEX LED
STEPPER 03
INDEX DETECTOR
STEPPER 01
STEPPER 02
TRACK 00 DETECTOR
WRITE HEAD
HEAD LOAD SOLENOID
ACTIVITY LIGHT ~ ~
TRACK 00 LED .. ~
WRITE
LOGIC
DRIVE
SELECT
READ
LOGIC
CONTROL
LOGIC
(HEAD LOAD)
(IN USE)
(DiSK CHANGE)
DRIVE SELECT
SEP DATA
POWER ON
RESET
SECTOR (SA801)
READY
INDEX
WRITE GATE
STEP
DIRECTION SELECT
WRITE DATA
SEP CLOCK
READ DATA
DRIVE SELECT (4 LINES)
TRACK 00
WRITE PROTECT (optional)
"T1
cO"
-e
...
CD
~
~
(J)
»
ex>
0
0
05
0
.....
11
C
::J
~
o·
::J
~
0
05"
<0
Q)
3

2.0 FUNCTIONAL CHARACTERISTICS
2.1 General Operation
The SA800/801 Diskette Storage Drive consists of read/write and controls electronics, drive mechanism,
read/write head, track positioning mechanism, and the removable diskette. These components perform the
following functions:
Interpret and generate control signals.
Move read/write head to the selected track.
Read and write data.
The relationship and interface signals for the. internal functions of the SA800/801 are shown in Figure 2.
The Head Positioning Actuator positions the read/write head to the desired track on the diskette. The Head
Load Actuator loads the diskette against the read/write head and data may then
be recorded or read from
the diskette.
2.2 Read/Write and Control Electronics
The electronics are packaged on one PCB. The PCB contains:
1. Index Detector Circuits. (Sector/Index for 801).
2. Head Position Actuator Driver.
3. Head Load Actuator Driver.
4. Read/Write Amplifier and Transition Detector.
5. Data/Clocl< Separation Circuits.
6. Write Protect.
7. Drive Ready Detector Circuit.
8. Drive Select Circuits.
2.3 Drive Mechanism
The Diskette drive motor rotates the spindle at 360 rpm through abelt-drive system. 50 or 60 Hz power is ac-
commodated by changing the drive pulley and belt. Aregistration hub, centered
on the face of the spindle,
positions the Diskette. Aclamp that moves
in conjunction with the cartridge guide fixes the Diskette to the
registration hub.
2.4 Positioning Mechanism
An electrical stepping motor (Head Position Actuator) and lead screw positions the read/write head. The
stepping motor rotates the lead screw clockwise or counterclockwise in 15° increments. A 15° rotation of the
lead screw moves the read/write head one track position.
The using system increments the stepping motor
to the desired track. .
2.5 Read/Write Head
The SA800/801 head is asingle element ceramic read/write head with straddle erase elements to provide
erased areas between data tracks. Thus normal interchange tolerances between media and drives will not
degrade the signal to noise ratio and insures Diskette interchangeability.
The read/write head is mounted
on acarriage which is located on the Head Position Actuator lead screw.
The Diskette is held in aplane perpendicular to the read/write head by aplaten located on the base casting.
This precise registration assures perfect compliance with the read/write head.
The Diskette is loaded
against the head with aload pad actuated by the head load solenoid.
The read/write head
is in direct contact with the Diskette. The head surface has been designed to obtain
maximum signal transfer to and from the magnetic surface of the Diskette with minimum head/Diskette
wear.
5

2.6 Recording Format
The format of the data recorded on the disk is totally afunction of the host system, and can be designed
around the users application to best take advantage of the total available bits that can be written
on anyone
track"
For adetailed discussion of various recording f:ormats, the systems designer should read one of the follow-
ing: .
1. IBM Compatibility Manual.
2. Shugart Associates Double Density Design Guide.
3. 8.A801/901 Track Formats.
2.7 Optional Features
t 1. -12 to -15 Volt DC to replace -5 Volt DC requirement.
2. Dust Cover, Not available on "R"series.
3. Write Protect for SA800. Standard on SA801 .
4. Door Lock. Will lock the door when drive is selected or through alternate I/O pin.
5. Horizontal mounting with door opening up.
6. SA800/801" R" Series. Allows two drives to be horizontally installed in astandard 19" Ret-
rna rack. Reference figure 20.
2.8 Model Differences
800-1 -Soft Sectored with an FM (single den-
sity) data separator.
800-2 -Soft Sectored without data separator.
800-4 -Mechanics only (No PCB).
801 -Hard Sectored with an FM (single
density) data separator and sector
separator.
NOTE: To convert a
801 to a800 move the shorting plug from the 801 position to the 800 position. A
800 cannot be
converted to a 801 .
tMinus voltages are not required for SA800L.
6

3.0 FUNCTIONAL OPERATIONS
3.1 Power Sequencing
Applying
AC and DC power to the SA800/801 can be done in any sequence, however, once AC power has
been applied, a 2 second delay must
be introduced before any Read or Write operation is attempted. This
delay is for stabilization of the Diskette rotational speed. Also, after application of
DC power, a90 millise-
cond delay must be introduced before a
Read, Write, or Seek opration or before the control output signals
are valid. After powering
on, initial position of the R/W head with respect to data tracks is indeterminant. In
order to assure proper positioning of the R/W head prior to any read/write operation after powering on, a
Step Out operation should be performed until the Track 00 indicator becomes active.
3.2 Drive
Se~ection
Drive selection occurs when adrive's Drive Select line is activated. Only the drive with this line active will
respondto input lines or gate output lines. Under normal operation, the Drive Select line will load the
R/W
head, apply power to the stepper motor, enable the input lines, activate the output lines and light the Activity
LED on the front of the drive. Optional modes of operation are available. Reference section 7for these user
installable features.
3.3 Track Accessing
Seeking the
R/W head from one track to another is accomplished by:
a. Activating Drive Select line.
b. Selecting desired direction utilizing Direction Select line.
c. Write Gate is being inactive.
d. Pulsing the Step line.
MUltiple track accessing
is accomplished by repeated pUlsing of the Step line until the desired track has
been
r~ached. Each pulse on the Step line will cause the R/W head to move one track either in or out depen-
ding
on the Direction Select line. Head movement is initiated on the trailing edge of the Step Pulse.
3.3.1 Step Out
With the Direction Select line at aplus logic level (2.5V to 5.25V) apulse
on the Step line will cause the R/W
head to move one track away from the center of the disk. The pUlse(s) applied to the Step line and Direction
Select line must have the timing characterisitics shown
in Figure 3.
3.3.2 Step In
With
the Direction Select line at aminus logic level (OV to AV), apulse on the Step line will cause the R/W
head to move one track closer to the center of the disk. The pulse(s) applied to the Step line must have the
timing characterisitics shown
in Figure 3.
3.4 Read Operation
Reading data from the SA800/801 Diskette Storage drive
is accomplished by:
a. Activating Drive Select line.
b. Write Gate being inactive.
The timing relationships required to initiate aread sequence are shown
in Figure 4. These timing specifica-
tions are reqUired
in order to guarantee that the R/W head position has stabilized prior to reading.
The timing
of the read signals, Read Data, Separated Data, and Separated Clock are shown in Figure 5.
7

----------"s s'------
DC POWER
DRIVE SELECT
DIRECTION SELECT
TRACK 00
OUTPUT SIGNAL
STEP
L,--------'s S,,-, -----
REVERSE
Figure 3. Track Access Timing
DC POWER
~~-----------"'~'--S --
~----------~S'---
U'-----"SS'\lo---
I
VALID READ DATA-------!-----!---- .....
~ 1~I~S
*2SECONDS IF AC AND DC POWER ARE APPLIED AT SAME TIME
STEP
WRITE GATE
DRIVE SELECT
Figure 4. Read Initiate Timing
8

u
I
B
LJ
50ns
IA I
B
l..- 200
I±50ns
IA
I
iJ i
----I J.-- 200 ±
I
U-U-U
--....J ~ 200 ±50ns
SEP CLOCK
SEP DATA
READ DATA
A= LEADING EDGE OF BIT MAY BE ±400 ns FROM ITS NOMINAL POSITION.
B= LEADING
EDGE OF BIT MAY BE ±200 ns FROM ITS NOMINAL POSITION.
Figure 5. Read Signal Timing
3.5 Write Operation
Writing data to the SA800/801 is accomplished by:
a. Activating the Drive Select line.
b. Activating the Write Gate line.
c. Pulsing the Write Data line with the data to be written.
The timing relationships required to initiate awrite data sequence are shown
in Figure 6. These timing
specifications are required
in order to guarantee that the R/W head position has stabilized prior to writing.
The timing specifications for the Write Data pulses are shown
in Figure 7.
3.6 Sequence of Events
The timing diagram shown in Figure 8shows the necessary sequence of events with associated timing
rEJstrictions for proper operation.
9

DC POWER
DRIVE SELECT
STEP
WRiTE GATE
WRITE DATA
_I
1---90MSM,N*i
,~_---=- _
1 .. 35MS~
--LI'~I--'-
---I r16MSMIN
-----I~ ---
---I 1--4.00/,8 MAX
----------------. ..... - ...
*2SECONDS IF AC AND DC POWER ARE APPLIED AT SAME TIME.
Figure 6. Write Initiate Timing
.WRITE DATA
I 150 ns MIN I.. .I..~
~ 11 OOns MAX 4.00JLs ± 20ns· 2.00JLs
± 10ns
Figure 7. Write Data Timing
10

s
MAX
SS'r---
S5~-L
-
l-ta MS MIN STEPPR ONLY
1---12lts MAX .S
I
H41'8
I~
III
90 MS MIN
_.
I1O.4ItSMINI- t
18 MS MIN
~ 1------..1 .. 1
35 MS MIN HEAD LOAD -I
_~ __ ~8_M_S _MI ..... N1 __ .. _-:flJUl ~c 5r
.
1_
35 MS MIN HEAD
LOAD_ ") _ ~ L
50ItSMIN~ I
90 MS MIN
AC POWER
STEP
VAll DCONTROL
OUTPUT SIGNALS
WRITE DATA
WRITE GATE
DC POWER
VALID READ
DATA SIGNAL
TRACK 0
OUTPUT SIGNAL
--.J1'-"' .. -- .. -12-S-EC-M-N---------~5 S~-
--.Jr----il~----~SS.....--
--j ~_90_M_S_M_IN ~S S--.---
+1 L· 500 NS MAX
Il~----~SS~-
~ .. 41'8~.IN
_
~_I __ ~~~I:--11t-S· M-IN-------"S s
DIRECTION SELECT ~
U
90 MS
~~ 11'8 MIN
DRIVE SELECT
-
NOTE 1: 35ms minimum delay must be introduced after Drive Select to
allow for proper head load settling. If stepper power is to be ap-
plied independent of Head Load, than and 8ms minimum delay
must be introduced to allow for stepper settling ..
General Control and Data Timing Requirements
11

4.0 ELECTRICAL INTERFACE
The interface of the SA800/801 Diskette drive can be divided into two categories:
1. Signal
2. Power
The following sections provide the electrical definition for each line.
Reference Figure 9for all interface connections.
4.1 Signal Interface
The signal interface consists of two categories:
1. Control
2. Data Transfer
All lines
in the signal interface are digital in nature and either provide signals to the drive (input), or provide
signals to the host (output), via interface connector P1/J1.
4.1.1 Input Lines
There are ten signal input lines, eight are standard and two are user installable options (reference section 7).
The input signals are of two types, those intended to be multiplexed in amUltiple drive system and those
which will perform the multiplexing.
The input signals to be mUltiplexed are:
1. Direction Select
2. Step
3. Write Data
4. Write Gate
The input signals which are intended to do the mUltiplexing are:
1. Drive Select 1
2. Drive Select 2
3. DriveSelect 3
4. 0rive Select 4
The input lines have the
follOWing electrical specifications. Reference Figure 10 for the recommended cir-
cuit.
True =Logical zero =
Vin ± O.OV to + O.4V
@Iin =40 ma (max)
False =Logical one =
Vin +2.5V to +5.25V
@Iin =0ma (open)
Input Impedence =150 ohms
13

SA800/801
FLAT RIBBON
OR
TWISTED PAIR
MAX 10
FEET
HOST SYSTEM DISK CHANGE*
J1
11
-12
IN USE* 16 15
---
II.
HEAD LOAD* 18 17
--
INDEX 20 19
~Il.
READY
22
21 ...
SECTOR (801 ONLY)
24 23
DRIVE SELECT 126 25
..
-
DRIVE SELECT 2-
28
27 ..
DRIVE SELECT 330 29
..
-
DRIVE SELECT 432
31
.~
DIRECTION SELECT 34 33
..
STEP
36 35
..
--
WRITE DATA 38
37 ..
-
WRITE GATE 40 39
-
TRACK 00 42
41
-WRITE PROTECT
(OPTIONAL)_
44 43
READ DATA 46 45
SEP DATA 48 47
SEP CLOCK 50 49
+5 VDC J5 6
-5
I
4.-
-
-5 VDCj-7 to -16 VDC) t·
3
-4
I
.-
-
DCGND
-+
24 VDC 2
--1
:I
+ 24 VRETURN
";:o~
-
ACINPUT
J4
FRAME GROUND
--
1
A~~D
ACINPUT
~~
--
FRAME GND
g TWISTE.D PAIR
NOTE: Not shown are 5of the 9Alternate I/O connections. The connections for these lines are on
pins
2, 4, 6, 8, 10 and 14. Signal return for these lines are on pins 1, 3, 5, 7, 9and 13 respec-
tively. Reference
SectionJ for uses of these lines.
*These lines are alternate input/output lines and they are enabled by jumper plugs. Reference
Section 7for uses of these lines.
t Minus voltages are not required for SA800L.
Figure 9. Interface Connections
14

4.1.1 Input Line Termination
The SA800/801 has been provided with the capability of terminating the four input lines, which are meant to
be mUltiplexed, by jumpering traces.
The four lines and their respective jumpering traces are:
1. Direction Select Trace "T3"
2. Step Trace "T4"
3. Write Data Trace "T5"
4. Write Gate Trace "T6"
In order for the drive to function properiy, the last drive on the interface must have these four lines ter-
minated. Termination of these four lines can
be accomplished by either of two methods.
1. As shipped from the factory, jumpers are installed on the terminator posts T3, T 4, T5, and T6. Remove
these shorting plugs from all drives except the last one
on the Interface.
2. External termination may be used provided the terminator is beyond the last drive. Each of the four lines
should be terminated by using
a150 ohm, 1A watt resistor, pulled up to +5 VDC.
4.1.1.2 Drive Select 1-4
Drive Select when activated to alogical zero level, activates the multiplexed I/O lines and loads the
R/W
head. In this mode of operation only the drive with this line active will respond to the input lines and gate the
output lines.
Four separate input lines, Drive Select
1, Drive Select 2, Drive Select 3, and Drive Select 4, are provided so
that up to four drives may be multiplexed together in asystem and have separate Drive Select lines. Traces
'DS1', 'DS2', 'DS3', and 'DS4' have been providedto select which Drive Select line will activate the inter-
face signals for aunique drive.
As shipped from the factory, ashorting plug is installed on 'DS1'. To select
another Drive Select line, this plug should be moved to the appropriate 'OS' pin. For additional methods of
selecting drives, see section
7~ 1.
4.1.1.3 Direction Select
This interface line is acontrol signal which defines direction of motion the R/W head will take when the Step
line
is pUlsed. An open circuit or logical one defines the direction as "out" and if apulse is applied to the
Step line the
R/W head will move away from the center of the disk. Conversely, if this input is shorted to
ground or alogical zero level, the direction
of motion
is defined as "in" and if apulse isapplied to the step line, the R/W head will move towards the
center of the disk.
4.1.1.4 Step
This interface line
is acontrol signal which causes the R/W head to move with the direction of motion as
defined by the Direction Select line.
The access motion is initiated
on each logical zero to logical one transition, or the trailing edge of the signal
pulse. Any change
in the Direction Selectline must be made at least 1 p,s before the trailing edge of the Step
pulse. The read/write head may
be prevented from stepping past track 00 by using the" NFO" trace option
on LSI PCB. Refer to Figure 3for these timings. Note: When going from areverse seek to aforward seek or
vice versa and additional 8ms delay must be induced before changing direction.
4.1.1.5 Write Gate
The active state of this signal, or logical zero, enables Write Data to be written on the diskette. The inactive
state, or logical one, enables the read data logic (Separated Data, Separated Clock,
and Read Data) and
stepper logic. Refer to Figure 6for timings.
15