Shugart SA 400 minifloppy User manual

SA400 CQ
m
minifloppyTM ~
Diskette Storage Drive ~~
~
2)
~
~
C=:=J

SA400 CQ
m
minifloppyTM ~
Diskette Storage Drive ~~
@)
2)
~
@)
C=:=J
© Copyright 1977 Shugart Associates

PREFACE
This manual describes the electrical and mechani-
cal characteristics
of the SA400 minifloppyr\fdrive
required
by customers who purchase it as an
OEM device.
It contains the timing, electrical and
mechanical specifications; recommended formats
and circuitry necessary
to interface it to a host
controller/formatter.
For maintenance information, reference the
SA400 Service Manual, P
/N 54096.
™Minifloppy, minidiskette and ministreaker are
Shugart Associates trademarks.

Table of Contents
1.0
2.0
3.0
4.0
Introduction . . . . . . . . .
1.1 Specification Summary . .
1.1.1 Performance Specifications
1.1.2 Functional Specifications
1.1.3 Physical Specifications. .
1.1.4 Reliability Specifications.
Functional Characteristics . . .
2.1 General Operation . . .
2:2 Read/Write and Control Electronics
2.3 Drive Mechanism. . . . . . .
2.4 R/W
Head Positioning Mechanism
2.5 Read/Write
Head.
2.6 Recording Format
Functional Operations. .
3.1 Power Sequencing
3.2 Drive Selection
3.3
Motor On. . . .
3.4 Track Accessing .
3.4.1 Step
Out. . .
3.4.2 Step
In. . . .
3.5
Read Operation
3.6 Write Operation
3.7 Sequence
of Events
3.8 Multiplex
Option.
3.8.1 Drive Selection
Electrical Interface . .
4.1 Signal Interface
4.1.1
Input Lines. .
4.1.1.1
Input Line Terminations
4.1.1.2 Drive Select 1-3
4.1.1.3
Motor On. . .
4.1.1.4 Direction Select
4.1.1.5
Step. . . . . .
4.1.1.6 Write Gate . . .
4.1.1.7 Write Data (FM)
4.1.2
Output Lines
4.1.2.1 Track
00
4.1.2.2 Index/Sector
4.1.2.3
Read Data . .
1
2
2
2
2
2
3
3
4
4
4
4
4
5
5
5
5
5
7
7
7
7
7
7
7
11
11
11
13
13
13
13
13
13
14
14
14
14
15

5.0
6.0
7.0
8.0
9.0
4.1.2.4 Write Protect .
4.2 Power Interface
4.2.1 Frame Ground.
Physical Interface
5.1 J 1/P1 Connector
5.2 J2/P2 Connector
5.3 Frame Grounding
Drive Physical Specifications
6.1 Mechanical Dimensions
6.2 Mounting.
R:ecording Format
7.1 Bit Cell
7.2 Byte...
7.3 Track Format
7.3.1 Soft Sectored Recording Format.
7.3.1.1 Gaps . . . .
7.3.1.2 Address Marks. . . . . . . .
7.3.1.3 CRC" . . . . . . . . . . .
7.3.1.4 Optional Soft Sectored Recording Format
7.3.2 Hard Sectored Recording Format
Application Notes . . . . .
8..1 Data Separator. . . .
8" 1.1 True FM Data Separator
8,,2 Read Data Circuits . .
8,,3 CRC Generating and Checking Circuitry.
8..4 Index/Sector and Ready Logic
8..5 Error Detection and Correction
8,,5.1 Write Error
8,,5.2 Read Error .
8 .. 5.3 Seek Error .
Operation Procedu res
9 .. 1Minidiskette Loading
9.2 Minidiskette Handling.
9.3 Write Protect Feature .
15
15
15
17
17
18
18
19
19
19
21
21
21
22
.22
22
24
26
26
26
.. 27
27
29
29
29
.34
34
34
34
34
39
39
40
40

List of Illustrations
1. SA400 Minifloppy Drive. .
2. SA400 Functional Diagram.
3. Track Access Timing
4. Read Initiate Timing
5. Read Signal Timing .
6. Write Initiate Timing
7. Write Data Timing .
8. General Control and Data Timing Requirements
9. Interface Connections .
10. Interface Signal Driver/Receiver .......
11. Index Sector Timing Soft Sectored (SA104 Media)."
12. Index Sector Timing Hard Sectored
13. J1 Connector Dimensions . . . .
14. J2 Connector .........
15. Interface Connectors-Physical Locations
16. SA400 Drive Dimensions.
17. Data Pattern
18. Bit Cell
19. Byte. . . .
20. Data Bytes .
21. Track Format-18 Records/Track
22. ID Address Mark ....
23. Data Address Mark . . . .
24. Deleted Data Address Mark.
25. Soft Sectored Formats. . .
26. Hard Sectored Formats . .
27. Data Separator Functional Diagram.
28. Data Separator Timing Diagram . .
29. True Data Separator ......
30. Register Controls and AM Detection
31. Data and Clock Registers.
32. AM Timing .
33. CR CGeneration ........
34. Index/Sector Separator and Ready Circuit
35. Index/Sector Timing . . . .
36. SA400 with SA4400 Controler
37. Loadi ng SA400 . . . .
38. SA104/1 05 Write Protect
3
6
6
8
8
8
9
12
14
14
14
17
18
18
20
21
21
22
22
23
24
25
25
26
26
28
28
30
31
32
33
35
36
37
38
39
40

FIGURE 1. SA400 MINIFLOPPY DRIVE

1.0 INTRODUCTION
The SA400 minifloppy™drive offers the system
designer the random access storage capability
of
floppy disk drives in apackage the size of most
cassette tape units.
It also provides superior data
integrity and faster throughput
of data when com·
pared with cassette drives.
The SA400
is based on the proven floppy disk
drive technology
of the Shugart SA800 drive. It
features aunique new direct drive stepping motor
actuator, utilizing aspiral cam with av-groove
positive detent which assures precise location of
the read/write head on atrack. The drive employs
the same proprietary glass bonded ferrite/ceramic
read/write head
as the SA800 uses. AC power
requirements have been eliminated through the
use of a DC servo-controlled spindle drive motor.
The drive
is also equipped with an interface which
allows upward expansion
of the units within the
system and future system enhancements with the
large floppy drive.
Applications for the minifloppy drive include
word processing and text editing systems; mini
and micro computer program storage; power
typing systems; "intelligent" desktop calculators
and the microcomputer hobby market.
The
SAl04/l05 minidiskette™media used with
the SA400
is similar to the standard flexible disk,
only smaller. It is available for soft (SAl04) or hard
(SAl05) sectored formats. The minidiskette
diameter
is 5.125 inches (130.2 mm) and the jacket
is asquare 5.25 inches (133.4 mm).

FM
SA 105 or SA107 minidiskette
(Hard Sectored)
SA104 minidiskette
(Soft Sectored)
1.1.2 functional Specifications
1.1.1 Performance Specifications
30 Minutes
Not Required
1per 108bits read
1per 10
11
bits read
1per 106seeks
5years
3.0 x106passes per track
8,000 Power
on Hours
(Typical Usage)
'1.1.4 Reliability Specifications
Mechanical Dimensions:
Width 5.75 in. (14.60 em.)
Height 3.25 in. (8.25 cm.)
Depth 8.00 in. (20.32 cm.)
Weight 3lbs. (1.36 kg.)
Power Dissipation =
15 watts (51 BTU/Hr) Operating (typical)
7.5 watts (26 BTU/Hr) Standby (typical)
*MTBF (Mean
Time Between
Failures)
PM (preventive
Maintenance)
MTTR (Mean Time
to Repair)
Error Rates
Soft Errors
Hard Errors
Seek Errors
Component Design
Life
Media Life
*MTBF assumes
duty cycle of spindle drive motor
to be 25% of POH.
40ms
463 ms
10ms
75 ms
1sec.
300
RPM
2581 BPI
5162 FCI
48 TPI
35
1.542 in. (3.916 em)
2.250 in. (5.715 cm)
1
Spec:ification Summary
average
settling time
Head Load Time
Disc Motor Start Time
Rotational Speed
Recording Density
(inside track)
Flux Density
Track Density
Tracks
Inside Track Radius
Outside Track Radius
Index
Encoding Method
Media Requirements
1.1
Capacity
Un forma tted
per disk 109.4K bytes
per track 3125 bytes
Formatted (Reference Section 7.0)
Soft Sectoring Hard Sectoring
per disk 80.6K bytes 72.03K bytes
per track 2304 bytes 2058 bytes
per sector 128 bytes 128 bytes
sectors per track
18 16
Transfer Rate 125
.OK bits/sec.
Latency (average) 100 ms
Access Time
track to track
1.1.3 Physical Specifications
1.8 amp
(maximum)
0.7 amp
(maximum)
Environmental Limits:
Ambient Temperature =
Operating Shipping Storage
40°F to 115°F -40°F to 144°F _8°F to 117°F
(4°C to 46°C) (-40°C to 62°C) (-22°C to 47°C)
Relative Humidity =
20% to 80% 1% to 95% 1% to 95%
Max. Wet. Bulb
::::
78°F (25°C) No Condensation
DC Voltage Requirements:
+12
VDC ± 5% 0.9 amp
(typical)
+5 VDC ± 5% 0.5 amp
(typical)
:2

2.0 FUNCTIONAL CHARACTERISTICS
2.1 General Operation
The SA400 minidiskette Storage Drive consists of
read/write, control and drive motor electronics,
drive mechanism, read/write head, track position-
ing mechanism, and removable minidiskette. These
components perform the following functions:
1. Interpret and generate control signals.
2. Move the read/write head
to the desired track.
3. Read and write data.
4. Control drive motor speed.
The interface signals and their relationship to the
internal functions
are shown in figure 2.
The head positioning actuator positions the read/
write head
to the desired track on the minidisk-
ette. The head load actuator loads the mini-
diskette against the read/write head and data
may then be recorded or read.
WRITE ROTECT IN/C)
WRITE PROTECT (COM)
READ
DATA
DRIVE SELECT
WRITE
DATA
WRITE GATE
WRITE PROTECT
DR IVE SELECT
STEP
DIRECTION SELECT
DRIVE SELECT 13 LINES)
TRACK 00
.INDEX/SECTOR
MOTOR ON
-------t
FlEAD
l.OGIC
WRITE
LOGIC
CONTROL
LOGIC
READ HEAD
WRITE HEAD
TRACK 00 (COM)
TRACK 00
IN/Ol
MOTOR ON
STEPPER ¢A
WRITE PROTECT
SWITCH
TACHOMETER
r.:..:ST:..::E~PP..::E:..:..R.:::.:¢B=-- ~ _
r.:..:ST:..::E~PP..::E:..:..Fl.:::.:¢C=-- _
STEPPER ¢D
INDEX/SECTOR LED
t-o----"--'-'--'-'-------------------------.--
r;.;.:IN:;:D::..:EX;:.:/S::E:;:CT:...::O:.:..:R....::D . ..:.ET:...:E:.::C:...:TO::..:.R=-- . __
'---_._-_ ...
FIGURE 2. SA400 FUNCTIONAL DIAGRAM
3

2.2 Read/Write and Control Electronics
The electronics are packaged on two PCB's. The
PCB's contain:
1. Index/Sector detector.
2. R/W head position actuator drivers.
3. R/W head load actuator driver.
4. Write current drivers.
5. Read amplifier and transition detectors.
6. Write protect detector.
7. Drive select circuits.
8. Drive motor control circuits.
2.3 DrivE! Mechanism
The minifloppy drive motor operates on 12 VDC
and rotates the spindle at 300 rpm through abelt-
drive system. The speed
of the motor is controlled
by afeed back from atachometer internal to the
motor. Aregistration hub, centered on the face
of the spindle, positions the minidiskette. Ahub
clamp that moves in conjunction with the door
closure mechanism centers and clamps the mini-
diskette
onto the spindle hub.
2.4 R/W Head Positioning Mechanism
An electrical stepping motor and aface cam
positions the read/write head. The stepping
motor
rotates the cam clockwise or counterclockwise
with two step increments per track. The using
system increments the stepper
motor to the
desired track
by selecting the proper direction
and issuing one step pulse per track. The drive
control electronics issues the second step pulse
needed per track.
2.5 Read/Write Head
The SA400 R/W head is asingle element glass
bonded ferrite/ceramic 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 nOlse Lilio and lnsures minidiskette
interchangeability.
The R/W head
is mounted on acarriage assembly
which moves on rails and
is positioned by the
cam. The mil:idj~.!':cttc is held in aplane perpen-
dicular to the R/W head by aplaten located on
the base casting. This precise registration assures
4
perfect compliance with the R/W head. The mini-
diskette is loaded against the head with aload pad
actuated by the head load solenoid.
The R/W head
is in direct contact with the mini-
diskette. The head surface has been designed
to
obtain maximum signal transfer to and from the
magnetic surface
of the minidiskette with mini-
mum head/minidiskette wear.
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 take
maximum advantage
of the total available bits
that can be written on anyone track.
For adetailed discussion of various recording
formats, reference section 7.0.

5
3.0 FUNCTIONAL OPERATIONS
This section of the manual defines the functional
as well as the timing relationships of the opera-
tions for the SA400.
3.1 Power Sequencing
Applying DC power to the SA400 can be done
in any sequence; however, during power up, the
Write Gate line must be held inactive
or at ahigh
level. This will prevent possible "glitching"
of the
media. After application
of DC power, a100 ms
delay should be introduced before any operation
is performed. Also, after powering on, initial
position
of the R/W head with respect to the data
tracks on the media
is indeterminant. In order to
assure proper positioning of the R/W head after
powering on, aStep
Out operation should be
performed until the Track
00 line becomes active
(Recalibrate).
3.2 Drive Selection
Drive Selection occurs when the Drive Select line
is activated. Under normal operation, the Drive
Select line will load the R/W head against the mini-
diskette enabling contact
of the R/W head with the
media and will also light aLED on the front plate.
3.3 Motor On
In order for the host system to read or write data
the
DC drive motor must be turned on. This is
accomplished by activating the line -Motor On.
Aone (1) second delay
must be introduced
after activating this line to allow the
motor to
come up to speed before reading or writing can
be accomplished.
The
motor must be turned off by the host system
by deactivating the Motor On line. This should be
done
if the drive has not received anew command
within two (2) seconds (10 revolutions
of diskette)
after completing the execution
of acommand.
This will insure maximum
motor and media life.
3.4 Track Accessing
Seeking the R/W head from one track to another
is accomplished by:
1. Activating the Drive Select line.
2. Selecting the desired direction l.ltilizing the
Direction Select line.
3. Write Gate being inactive.
4. Pulsing the Step line.

WRITE GATE
-------------, '\.,--------------
------~ i1
I
-------~
DRIVE SELECT
I'
1' _
1------------.-1\. )'
REVERSE
DIRECTION SELECT ..... __ -,
FORWAFlD ( ( I
,,
-1 r-
1
~ruMIN ~
l~MIN r-- -I
--------- ...
l~MIN~_r_ ~40MSMIN
STEP
FIGURE 3. TRACK ACCESS TIMING
-
--------------\, ",' ------
• j
DC POWER
MOTOR ON
DRIVE SELECT
.,
~I""-----------------------~J ""J-------
~ ~~100 MS MIN
--- ..... - ......
L.. . -\~ \-\ _
STEP ---_._--------------\',
\-----
WRITE GATE
VALID READ DATA -t_--ll-----+----_--,
t4---75MSMIN-
"'---1 SEC MIN---
FIGURE 4. READ INITIATE TIMING
6

Multiple track accessing is accomplished by
repeatedly pulsing the Step line until the desired
track has been reached. Each pulse
on the Step
line will cause the R/W head
to move one track
either in or out depending on the Direction Select
line. Head movement and direction latching
is
initiated on the trailing edge of the Step pulse.
During aRecalibrate (Step to Track 00), the worst
case number of step pulses required is 58. The
worst case occurs when the carriage
is positioned
IN beyond track 34 and the carriage comes out of
the spiral cam groove. In this case, it can take up
to 24 steps for the carriage to pick up the groove
in the cam and then another 34 steps
to reach
track 00.
3.4.1 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 the Direction Select line must have the
timing characteristics shown in Figure 3.
3.4.2 Step In
With the Direction Select line at aminus logic
level
(OV to .4V), 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 characteristics
shown in figure 3.
3.5 Read Operation
Reading data from the SA400 minifloppy 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
specifications are required in order to guarantee
that the R/W head position has stabilized prior to
reading.
The timing
of Read Data is shown in figure 5.
3.6 Write Operation
Writing data to the SA400 is accomplished by:
a. Activating the Drive Select line.
7
b. Activating the Write Gate line.
c. Pulsing the Write Data line with the data to
be written.
The timing relationships reqUired to initiate a
write data sequence are shown in Figure 6. These
timing specifications
are required in order to
guarantee that the R/W head position has stabi-
lized prior
to writing.
The timing specifications for the Write Data pulses
are shown in figure 7.
3.7 Sequence of Events
The timing diagram shown in figure 8shows the
necessary sequence
of events with associated
timing restrictions'for proper operation.
3.8 Multiplex Option
As shipped from the factory, the drive is set to
operate as asingle unit or in anon-multiplexed
mode. For multiplexed or "daisy chained" opera-
tion, the trace labeled "MUX" must be cut.
3.8.1 Drive Selection
In amultiple drive system (trace "MUX" cut),
only the drive with its Drive Select line active will
load its R/W head, respond to the input lines and
gate the
output lines.
Three separate input lines, Drive Select
1, Drive
Select 2and Drive Select 3, are provided
so that
up to three drives may be multiplexed on asingle
I/O cable in asystem. A"Program
Shunt" in Ie
location 1F, position 1, 2and 3with designators
DS 1, DS2 and DS3, has been proVided to select
which Drive Select line will activate the interface
'signals for aunique drive. As shipped from the
factory this program shunt has the three locations
,shorted. To set an address on adrive, its location
should remain shorted and the other two locations
should be cut. For methods
of cutting the program
shunt traces, reference section 4.1.1.2.

READ DATA "'II
I
AI
BI
AI
A
4.0j.1s 4.0j.1s
NOM. NOM.
I
BI A
MOTOR ON
A=
LEADING EDGE OF BIT MA YBE ± 800 ns FROM ITS NOMINAL POSITION.
B= LEADING EDGE OF BIT MAY BE ± 400 ns FROM ITS NOMINAL POSITION.
FIGURE 5. READ SIGNAL TIMING
1 . -1. •• p.----------- __
JJ
DRIVE SELECT .... _
1&-... --'\ '~J ----------
f.-75 MS MIN_
STEP
WRITE GA.TE
WRITE DATA
...-- ... ------r.\ ~\ ---------
.. 4--50 MSMIN
14-_--1 SEC MIN ---II __ ~
FIGURE 6. WRITE INnlATE TIMING
WRITE DATA
I 250 ns MIN I8.00j.1s:! 40 ns I
~2100nSMAX ~ ~
FIGURE 7. WRITE DATA TIMING
8
4.00j.1s I
:! 20 ns r---

500 ns MAX
------------"""'\"""\ -----
...... _------------------\ ""\ ------
------------------------"'\', '~J---------
DRIVE SELECT
VALID TRK. 00
AND WRT. PROT. -----+--t--i
OUTPUT
MOTOR ON
POWER ON
1
S~EC------------------\\"'--------
MAX
VALID INDEX/
SECTOR OUTPUT
~---,---------------~~\o~---------
~500nSMAX
DIRECTION
SELECT
...-------...I\i ""\------
STEP
WRITE GATE
WRITE DATA
VALID
READ DATA
1----1 J,Js MIN
ir----------...I\i \-\ ------
50 MS
MIN
14 75 MS MIN _-+- __ --I~ .. ~-----""'\ ~- .~~ -J
'SEeMIN ~
-:-:1 J.---1 00 J,Js MIN
-------\\ lflJ
104---- 75 MS MIN ------I.
~-----1 SEC MIN---- ...
FIGURE: 8. GENERAL CONTROL AND DATA TIMING REQUIREMENTS
9

THIS PAGE INTENTIONALLY LEFT BLANK
10

11
4.0 ELECTRICAL INTERFACE
The interface of the SA400 minidiskette 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 eitner provide signals
to the drive (input), or
provide signals to the host
(output), via interface
connector
PI /J 1.
4.1.1 Input Lines
The input signals are of 3types, those intended
to be multiplexed in amultiple drive system, those
which will perform the multiplexing and Motor
Control.
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. Drive Select 3
The input lines have the following electrical speci-
fications. Reference Figure 10 for the recom-
mended circuit.
True =Logical zero =Yin
±O.OV to +OAV
@lin = 40 rna (max)
False =Logical one =Yin +2.5V to +5.25V
@lin:;: 0rna (open)
Input Impedance =150 ohms

HOST SYSTEM
FLAT RIBBON OR
TWISTED PAIR
SA400
MAX 10 FEET
J1
7-
INDEX/SECTOR
8
9----4~
DRIVE SELECT 1·
11----4~
-10
DRIVE SELECT 2
13~~
~
12
DRIVE SELECT 3·
14
15~~
MOTOR ON ·
17----4_
16
DIRECTION SELECT
·19
----4.
18
STEP
21----4_
20
WRITE DATA
23----4_
22
WRITE GATE
25---1.
-
24
TRACK 00
27~.
26
-
WRITE PROTECT
29~
28
-
READ DATA
30
-
+5 VDC
J2
X-4
3~_
+5 RETURN
L-
+12 VDC
r"\.
12
-X
+12 RETURN
-
":..-:'"
DC GND
--
m~
"""
AC GND
TWISTED PAIR
FRAME GND
FIGURE 9. INTERFACE CONNECTIONS
12

4.1.1.1 Input Line Terminations
The SA400 has been provided with the capability
of terminating the five input lines listed below.
1. Motor On
2. Direction Select
3. Step
4. Write Data
5. Write Gate
These lines are terminated through a150
ohm
resistor pack installed in adip socket located at Ie
location 1E.
In asingle drive system this resistor pack should be
kept in place to provide the proper terminations.
In amultiple drive system (Program
Shunt position
"MX" open) only the last drive on the interface is
to be terminated. All other drives on the interface
must have the resistor pack removed. External
terminations may also be used, then the user must
provide the terminations beyond the last drive and
each
of the five lines must be terminated to
+5VDC through a150 ohm ~ watt resistor.
4.1.1.2 Drive Select 1-3
The SA400 as shipped from the factory is con-
figured
to operate in asingle drive system. It can
be easily modified
by the user to operate with
other drives in amultiplexed multiple drive system.
The user can activate the multiplex option
by cut··
ting the
"MX" position of the programmable shunt
located in
IC location 1F. This will allow the
multiplexing
of the I/O lines.
In asingle drive system (program shunt position
"MX" shorted), with program shunt position "HL"
shorted, Drive Select when activated to alogical
zero level, will load the R/W head against the
diskette enabling contact
of the R/W head against
the media. Since
"MX" is shorted, the I/O lines are
always enabled.
In amultiple drive system (program shunt position
"MX" open) the three input lines (Drive Select 1,
Drive Select 2and Drive Select 3) are provided so
that the using system may select which drive on
the interface
is to be used. In this mode of opera-
tion only the drive with its Drive Select line active
will respond to the
input lines and gate the output
lines. In addition, the selected drive will load its
R/W
~ead if program shunt position "HL" is
shorted.
13
The program shunt,
IC location 1F, positions
"DSl", "DS2" and "DS3", are to be used to select
which Drive Select line will active the I/O lines for
aunique drive.
As an example, if the user wants
the first drive on the interface to be address 1, he
must cut program shunt positions
"DS2" and
"DS3", and leave "DSl" intact.
The program shunt
is AMP part number 435704-6.
The shunt positions can be cut using AMP's tool
part number 435705. The shunt
is installed in a
dip socket and at the user's
option be removed and
be replaced
by adip switch (AMP PIN 435626-4).
The user may also choose
to have the program
shunts pre-programed
and/or color coded by AMP.
For this service contact your local AMP
representative.
4.1.1.3 Motor On
This input when activated to alogical zero level
will
turn on the drive motor allowing reading or
writing on the drive. Aone (1) second delay after
activating this line must be allowed before reading
or writing. This line should be deactivated, for
maximum
motor life, if no commands have been
issued
to the drives within two seconds (10 revo-
lutions
of the media) after completion of apre-
vious command.
As discussed in section 4.1.1.2, when program
shunt position
"HL" is shorted the R/W head will
load when the Drive Select line
is activated. Auser
selectable
option is available where by the R/W
head will load when the Motor On line
is activated.
This
is accomplished by moving the program shunt
over one position in its socket so position
"MH" is
shorted and position "HL" is open. With position
"MH" shorted, the R/W head will load when the
Motor On line
is activated to alogical zero level.
4.1.1.4 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 is applied to the step line, the R/W
head will move towards the center
of the disk.