Seagate ST212 User manual

ST212 PRODUCT MANUAL
March 24, 1986©
36010-001, Revision B
Seagate reserves theright to change, without notice,
the specifications contained in this manual.
Seagate •920 Dise Drive, Seotts Valley, CA 95066-4544, USA
Tel. [phone] •Telex 176455 SEAGATE SCVL

TABLE Of CONTENTS 1.0 SPECIFICATION
SUMMARY.................................. 1
1.1 Performance Specifications.......... .......................... .. 1
1.1.1 Access Time Definition and Timing 1
1.2 Functional Specifications. ..................................... .. 1
1.3 Physical Specifications 1
1.4 Reliability Specifications..................... .. . . . . . . . . . . . . . . . .. 1
1.4.1 Read Error Rates 1
1.4.1.1 Bit Jitter............................ ................. .. 2
1.4.2 Media Defects 2
1.5 Environmental Specifications 2
1.5.1 Ambient Temperature 2
1.5.2 Temperature Gradient 2
1.5.3 Relative Humidity 2
1.5.4 Altitude Limits 2
1.5.5 Operating Shock............................................ 2
1.5.6 Nonoperating
Shock........................................ 2
1.6 DC Power Requirements 3
1.6.1 Input Noise Ripple 3
1.6.2 Input Noise Frequency. ...................................
.. 3
1.7 Mounting Requirements 4
1.7.1 Handling and Static-Discharge Precautions. .................. .. 5
2.0 ST212 HOST/DRIVE INTERFACE 6
2.1 Control/Status SignaIs: PCB Edge-Connector JI ................. .. 6
2.2 Data Signals:PCB Edge-Connector J2.. . . . . . . . . . . . . . . . . . . . . . . . .. 8
2.3 DC Power: Connector J3 10
2.4 Frame Grounding: Lug JI0 10
3.0 DRIVE CONFIGURATION 11
3.1 Drive Configuration: Shunt J9 (MLC-Ol) 11
3.2 Drive Select Il
3.2.1 Daisy-chain 11
3.3 Radial 12
3.4 Write Fault 12
3.5 Life Test 12
4.0 CONTROL INPUT SIGNAIS 13
4.1 Head Select 2°, 21
,22,23
•••••••••••••••••••••••••••••••••••••••• 13
4.2 Write Gate 13
4.3 Step 14
4.3.1 Buffered Seek 14
4.3.2 Slow-step (Single-track) 15
4.3.3 Auto-truncation 16
4.4 Direction In 16
4.5 Drive Select 16
S.O CONTROL OUTPUT SIGNALS 18
5.1 Drive Selected 18
5.2 Index 18
5.3 Track 0 18
5.4 Ready 18
5.5 Seek Complete 19
5.6 Write Fault 19
5.6.1 Write Fault Signal Generation 19
5.6.1.1 Write Current Interruption ,20
5.7 Fault Detection: PC Board 20292-XXX 20
5.7.1 Voltage and Head Select Comparator 20
5.7.2 Write Fault Reset 20
5.8 Fault Detection: PC Board 20243-XXX 21
5.8.1 Voltage Comparator ~ .. 21
5.8.2 Head Select Comparators 21
6.0 READ/WRITE OPERATIONS .; 22
6.1 Write Operation: PC Board 20292-XXX 22
6.1.1 MFM Write Data '22
Table of Contents iii

6.1.2 Write Gate 23
6.1.3 Write DataProcessing 23
6.1.4 Precompensation 23
6.2 Write Operation: PC Board 20243-XXX 24
6.2.1 Write Gate ' 24
6.2.2 Line Receiver 24
6.3 Formatting 25
6.4 Read Operation: PC Board 20292-XXX 26
6.4.1 MFM Read Data ' 26
6.4.2 Head Select 26
6.4.3 LSI Preamp 26
6.4.4 Low Pass Filter 26
6.4.5 Read Data Conversion 26
6.5 Read Operation: PC Board 20243-XXX 27
6.5.1 Head Select 27
6.5.2 LSI Preamp ~ 27
6.5.3 Low Pass Filter 27
6.5.4 Phase Shifter ;, 27
6.5.5 Zero Cross Detector 27
6.5.6 Time Domain Filter 28
6.5.7 Line Driver 28
7.0 MICROPROCESSOR 29
7.1 MPU: PC Board 20292-XXX ...........................•........ 29
7.2 MPU: PC Board 20243-XXX 30
8.0 MOfOR SPEED CONTROL 31
8.1 Motor Speed Control: PC Board 20292-XXX 31
8.1.1 Hall Effect Transducer 31
8.1.2 Spindle Motor Control LSI 31
8.2 Motor Speed Control PC Board: 20249-XXX 31
8.2.1 Hall Effect Transducer 32
8.2.2 Speed Reference Circuit 32
8.2.3 Pulse Shaper 32
8.2.4 Integrator 32
8.2.5 Current Limit 32
8.2.6 Microprocessor: Motor On 32
8.2.7 Motor Drivers 32
8.2.8 Dynamic Brake 32
9.0 FIELD SERVICE ' 33
9.1 Test Point Data: PC Board 20292-XXX 33
9.1.1 DifferentiaI Read Filter: Test Points 1and 2 34
9.1.2 Track 0Sensor: IC 3B, Pin 134
9.1.3 Index Sensor: Test Point 9 34
9.2 Test Point Data: PC Board 20243-XXX 35
9.2.1 DifferentiaI Read Filter: Test Points 1and 2 35
9.2.2 Read Data: Test Points 3and 4 36
9.2.3 Track 0: Test Point 5.- 36
9.2.4 Index Sensor: Test Point 6 36
9.3 Field Accessible Components 36
9.3.1 Main Control PC Board 37
9.3.2 Motor Control PC Board Removal (MLC-OO only) 37
9.3.3 Index Sensor Removal 38
9.3.4 Installing the Optional Full-height Front Panel 38
9.3.5 Track 0Sensor Removal 39
Schematics
PCB 20243-XXX .......................•..... ' 41
PCB 20249-XXX 43
PCB 20292-XXX ' .. ' 45
iv
Table of Contents

FIGURES
FIGURE 1: Typical +12 Volt DC Start-up Current Profile 3
FIGURE
2: Mounting Dimensions : 4
FIGURE
3: JI Connector Dimensions. ........................... .. 6
FIGURE
4: Control/Status SignaIs. .............................. .. 7
FIGURE
5: J2 Connector Dimensions. ........................... .. 8
FIGURE
6: Data SignaIs 9
FIGURE
7: Host/Drive Interface and Drive Configuration 10
FIGURE 8: Daisy-chain Configuration ~ 11
FIGURE 9: Radial Configuration 12
FIGURE 10: Control SignaIs Driver/Receiver Combination 13
FIGURE Il Read/Write Timing 14
FIGURE 12 General Step Timing 15
FIGURE 13: Slow-step Timing 15
FIGURE 14: Auto-truncation Timing 16
FIGURE 15: Drive Select 17
FIGURE 16: Typical Power-up Sequence 19
FIGURE 1'7: Fault Detection PC Board 20292-XXX 20
FIGURE
18: Fault Detection PC Board 20243-XXX 21
FIGURE 19: Data Signal Driver/Receiver Combination 22
FIGURE 20: Write Operation PC Board 20292-XXX 22
FIGURE 21: Write Operation PC Board 20243-XXX 24
FIGURE
22: 17-Sector, 512-Byte/Sector Format Example 25
FIGURE 23: Read Operation PC Board 20292-XXX 26
FIGURE
24: Read Operation PC Board 20243-XXX 27
FIGURE 25: MPU: PC Board 20292-XXX 29
FIGURE
26: MPU: PC Board 20243-XXX 30
FIGURE
27: Motor Speed Control: PC Board 20292-XXX 31
FIGURE 28: Motor Speed Control: PC Board 20249-XXX 31
FIGURE 29: Test Point Locations PC Board 20292-XXX 33
FIGURE 30: DifferentiaI Read Filter 34
FIGURE 31: Index Sensor 34
FIGURE
32: Test Point Locations PC Board 20243-XXX 35
FIGURE 33: Read Data 36
FIGURE 34: ST212 PC Board Removal 37
FIGURE 35: Index Sensor Adjustment/Removal 38
FIGURE 36: Track "Sens or Removal 39
TABLES
TABLE 1: JI Host/Drive Pin Assignments. ........................ .. 7
TABLE
2: J2 Host/Drive Pin Assignments. ........................ .. 9
TABLE
3: Precompensation Pattern 23
ST212 PRODUCT MANUAL/Rev. B.v

PERFORMANCE SPECIFICATIONS
1.0
SPECIFICATION
SUMMARY
CAPACITY
Per Drive:
Per Surface:
Per Track:
Per Sector:
Sectors
Per Track:
UNFORMATTED
12.76 MB
6.38 MB
10,416 Bytes
NA
NA
FORMATTED
10.0 MB
5.0 MB
8,192 Bytes
256 Bytes
32 Sectors
1.1
ACCESS TIME DEFINITION AND TIMING 1.1.1
23.0 msec. max.
65.0 msec. max!
170.0 msec.
Access
time is defined as the time from the leading edge of the last Step pulse
received
to SEEK COMPLETE (including settling). The Step pulse period must
be between 5 p,sec. to 500 p,sec.
Track-to-Track:
Average:
Maximum:
FUNCTIONAL SPECIFICATIONS
1.2
Rotational Speed:
Average Latency:
Recording Density:
Track Density:
Cylinders:
Tracks:
Discs:
Recording
Method:
Data Transfer Rate:
3,600
RPM ± 1070
8.33 msec.
10,560
BPI/FCI
550 TPI
306
1,224
1
MFM
5.0 Megabits/second
PHYSICAL SPECIFICATIONS 1.3
Height:
Width:
Depth:
Weight:
1.63 inches max. (41.4
mm)
5.75 inches max. (146.05 mm)
8.00 inches max. (203.2 mm)
3.00 lbs (1.4 Kg)
RELIABILITY SPECIFICATIONS 1.4
MTBF:
PM:
MTTR:
Service Life:
11,000 Power-on
Hours
2
Not Required
30 Minutes
5Years
READ ERROR RATES
Recoverable Read Errors:
Nonrecoverable Read Errors:
Seek Errors:
1
per 1010 bits read 3
1 per 10
12
bits read 4
1 per 10
6seeks
1.4.1
1. Buffered-Seek
2. Typical usage at 25 oC at sea level. Calculated per Mil. Spec. 217.
3. Recoverable within 16 retries
4. Not recoverable within 16 retries
ST212
PRODUCT MANUAL/Rev. B1

1.4.1.1 BIT-JITTER
Bit jitter reduction determines the relationship between theleading edge of Read
data and the center of the data window.
The specified Read error rates are based
on the following bit jitter specifica-
tion: The
data separator must provide at least -40 dB of bit jitter reduction- at
2F with an offset error of less than 1.5 nsec. shift from the center of the data
window.
1.4.2 MEDIA DEFECTS
Amedia defect is aRead error when data, which has been correctly written,
cannot be recovered within
16 retries.
Aprintout will be provided with each drive shipped-listing the location
of any
defect by head, cylinder, sector and byte.5It will also specify the number
of bytes
from Index.
There will be no more
than four (4) defects per Read/Write head for amaxi-
mum total of sixteen (16) per drive. Cylinder Zero will be free of defects.
1.5
1.5.1
Operating:
Nonoperating:
1.5.2
Operating:
Nonoperating:
1.5.3
Operating:
Maximum
Wet Bulb:
Nonoperating:
1.5.4
Operating:
Nonoperating:
1.5.5
ENVIRONMENTAL SPECIFICATIONS
AMBlENT TEMPERATURE
10 oC to 45 oC (50 OF to 113 OF)
-40°C to 60°C (-40°F to 140°F)
TEMPERATURE GRADIENT
10°C/hr (18°F/hr) max.
Below condensation
RELATIVE HUMIDITY
8to 80070 noncondensing
26
oC (78.8 OF)
5to 95070 noncondensing
ALTITUDE LIMITS
-1,000 ft to 10,000 ft
-1,000 ft to 30,000 ft
OPERATING SHOCK
Maximum permitted shock without incurring nonrecoverable errors: 10 O's 6.7
1.5.6 NONOPERATING SHOCK
Maximum permitted shock without incurring physical damage or degradation
in performance: 40
0'S8 ..
5. Based on a32-sector, 256 byte/sector format
6. Il msec. -half-sine wave shock pulse.
7. Input levels at the drive mounting screws, drive mounted in an approved orientation.
8. Il msec., half sine-wave
2ST212
PRODUCT MANUAL/Rev. B

OC POWER REQUIREMENTS 1.6
The ST212 is listed in accordance with UL 478 and CSA C22.2 (0-MI982), and
meets
aIl applicable sections of IEC 380 and VDE 0806/08.81, as tested by TUV-
Rheinland, North America.
Power may be applied or removed in any sequence without loss of data or damage
to the drive.
+12 VDC
Voltage Tolerance (inc. ripple):
Maximum Current
at Power-on:
± 5070 Both seek and non-
seek conditions
3.2 Amp
1.0 Amp typical
+5 VDC:
Voltage Tolerance (inc. ripple):
Maximum Current
at Power-on:
POWER:
± 5070 Both seek and non-
seek conditions
1.2 Amp
1.0 Amp typical
17 Watts typical
INPUT NOISE RIPPLE
1.&.1
The maximum permitted ripple is 50 mV (peak-to-peak) on either + 12 Volts
or +5 Volts.
INPUT NOISE FREQUENCY
20 MHz max. on both the + 12 VDC and + 5 VDC Hnes.
1.&.2
AMPS r------~-----...,...-----~
15
10
5
4.0 t---------+------4-------I
3.5
3.2~---llIo....
3.0
2.5
2.0
t---------+------4-~-----I
.5
0.0 ..... ---"' ....... ~
o
1.5
1.0
FIGURE 1:
Typical
+12Volt OC
Start-up Current
Profile
SECONDS
ST212 PRODUCT MANUAL/Rev. B3

FIGURE 2:
Mounting Dimensions
r'195
"010
1 [4,96,.020mm)
1.87,.02
1 [47,50,.050mm)
---,
1.682 .. 010
[42,73, .020mm)
.39,.01 ~26"02
[9,91,.02mm) [,67,.05mm)
..
1
k3.12,.02
1 [79,25,.05mm)
_------ 8.00 MAX. ...... _,
[202,2mm)
MOUNTING HOLES:
40n Bottom,
4 On Each Side
#6-32 UNe X .31 [7,88mm)
Deep(12X)
m
5.75 MAX.
[146,05mm)
5.50,.02
[139,70,.05mm)
5.875,.010
[149,23,.020mm)
INCHES (MM)
1.7 MOUNTING REQUIREMENTS
The ST212 may be mounted in the following orientations:
Horizontal: Spindle motor down
Sides: Left
or right
Refer to
Figure 2for mounting dimensions.
Thedrive should not betilted front to back, in any position, by more than ±5
o.
For optimum performance the drive should be formatted in the same orienta-
tion as it will be mounted in the host system.
Aminimumclearance of 0.050 inch should be allowed around theentire perimeter
of the drive to allow for cooling airflow and motion during mechanical shock
or vibration.
It is recommended that any external shock mounts between the drive and the
host frame be designed so that the composite system has avertical resonant fre-
quency of 25Hz or lower.
4 ST212 PRODUCT MANUAL/Rev. B

HANDLING &STATIC-DISCHARGE PRECAUTIONS
After unpacking, and prior to system integration, the drive is exposed to poten-
tial handling and ESD hazard.
Do not touch the PCB edge-connectors, board components or the printed cir-
cuit cable without observing static-discharge precautions. Handle the drive by
the frame only.
It
is strongly recommended that the drive always rest on apadded surface until
it
is mounted in the host system.
ST212 PRODUCT MANUAL/Rev. B5

This section details the physical specifications of the host/drive interface con-
nectors. Connector dimensions
and pin assignments foHow under each section.
Refer below
to Figure 7for an overall view of the drive interface connectors.
2.1
CONTROL AND STATUS SIGNALS:
PCB EDGE-CONNECTOR
J1
2.0
ST212
HOST/DRIVE
INTERFACE
Do not touch the peB edge-connectors, board components or the printed cir·
cuit cable without observing static-discharge precautions. Handle the drive
by
the frame only.
Control
and status signais between the host andthe drive are transmitted through
a34-pin PCB edge-connector,
JI. Figure 3indicates connector dimensions and
Table llists the pin assignments. Ahost/drive interconnection is illustrated in
Figure 4.
Withthe drive resting on apadded surface, oriented with the Main Control PCB
up and the edge-connectors toward you, 11 is to your left and J2 is on the right.
Refer to Figure
7.
JI pins are numbered 1through 34 with the even pins located on the component
side
of the PCB. AH odd pins are ground. A key slot is provided between pins
4
and 6. Pin 2is labeled. The recommended mating connector for 11 is AMP
ribbon connector part number 88373-3.
6
.087
-l r .037 ±.003
~
.450
1
~
1 1
1- .. ----16 EQ. SP. at .100= 1.600-----II .. ~1
1-.--------1.775--------.-j
BOARD THICKNESS: 0.062 ±0.007
TOLERANCE: O.XXX ±0.005
(unless otherwise noted)
ST212 PRODUCT MANUAL/Rev. B
FIGURE 3:
J1 Connector
Dimensions

TABLE 1:
J1 Host/Drive
Pin Assignments GROU
ND
SIGNAL
RTN PIN PIN SIGNAL NAME
12RESERVED
34RESERVED
56-WRITE GATE
7
8t
-SEEK COMPLETE
910 -TRACK
~
11
12t
-WRITE FAULT
13 14 -HEAD SELECT
20
15 16
RESERVED
17 18 -HEAD SELECT 21
19
20t
-INDEX
21
22t
-READY
23 24 -STEP
25 26 -DRIVE SELECT 1
27 28 -DRIVE SELECT 2
29 30 -DRIVE SELECT 3
31
32 -DRIVE SELECT 4
33 34 -DIRECTION
IN
tST ATUS ENABLED WITH DRIVE SELECT
FLAT RIBBON OR
TWISTED PAIR 20 FT. MAX 1 -
RESERVED 2
•
3'1~
RESERVED 4
5~~
·WRITE GATE -6
..
7 -4~
..
:: SEEK COMPLETE 8
9~~
·
.:::
TRACK _10
11-1~
•WRITE FAULT 12
•
13~~
HEAD SELECT 2°
~
14
•
15-4~
RESERVED 16 17
"'1~
·HEAD SELECT 21-;- 18
19, t
-INDEX 20 21-4
~
•
...
-READY
22 23-4_
STEP -24
..
25-i~
DRIVE SELECT 126 27-4_
..
DRIVE SELECT 2-28
..
29~~
..
DRIVE SELECT 3
-;
30
31 '1~
....
DRIVE SELECT 432
33-4~
·DIRECTION
IN
-;-
34
-==-
-
"
+5 VOLTS OC
-4
l+ 5 VOLTS RETURN 3
....
....,
r"\
+12 VOLTS OC
-=-
1
l
•
'\J
+12 VOLTS RETURN -2
-==
-
DCGND
~
~
"...77 TWISTED PAIR
FRAME GND (18 GA
or larger) FRAME GND
FIGURE 4:
Control/Status Signais
HOST
ST212 PRODUCT MANUAL/Rev. B
ST212
J1
l
J3
J
7

2.2 DATA SIGNALS: PCB EDGE-CONNECTOR J2
Do not touch the PCB edge.connectors, board components or the printed cir-
cuit cable without observing static-discharge precautions. Handle the drive by
the frame ooly.
Read/Write
data signaIs are received and transmitted over a20-pin PCB edge-
connector, J2. Figure 5indicates connector dimensions
and Table 2lists the pin
assignments. Ahost/drive interconnection
is illustrated in Figure 6.
With thedrive resting on apaddedsurface, oriented with the Main Control PCB
up and the edge-connectors toward you, J2 is to your right and JI is on the left.
Refer
to Figure 7.
J2 pins are numbered 1through 20 with the even pins located on the compo-
nent side
of the PCB. A key slot is provided between pins 4 and 6. Pin 2is la-
beled. The recommended mating connector for J2
is AMP ribbon connector,
part number 88373-6.
FIGURE 5:
J2 Connector
Dimensions
1--.
050
120
ooo~ ~
1
1
.450
2 4
1
.087 ~
Fr------I
.400
LL""I+I- .... " .... ------ ........... ~
.150 1
1
1-
1
9EO. SP. at .100 = .900---1 __ 1
.-------1.075-------I~
BOARD THICKNESS: 0.062 ±0.007
TOLERANCE: O.XXX ±0.005
(unless otherwise noted)
8
ST212 PRODUCT MANUAL/Rev. B

TABLE 2:
J2 Host/Drive
Pin Assignments GROUND SIGNAL
RTN PIN PIN SIGNAL NAME
21-DRIVE SELECTED
43RESERVED
65RESERVED
87RESERVED
10 9RESERVED
12
11
GROUND
13 +MFM WRITE DATA
14 -MFM WRITE DATA
16 15 GROUND
17 +MFM READ DATA
18 -MFM READ DATA
20
19 GROUND
FLAT RIBBüN OR
TWISTED PAIR 20 FT. MAX
~ - DRIVE SELECTED-
1
2-
RESERVED 3
4-4~
RESERVED 5
6-i~
RESERVED
7
8-4~
RESERVED 9
RESERVED 10
GROUND
11-i.
12~.
~ +MFM WRITE DATA ~
13
~ -MFM WRITE DATA-----... 14
GROUND
15-4.
..
16-4.
~+ MFM READ DATA-
17
~ -MFM READ DATA-
18
GROUND
19~.
20-1~
_1.-
-......-
-
--
FIGURE 6:
Data Signais
HOST
ST212 PRODUCT MANUAL/Rev. B
ST212
J2
.9

2.3 OC POWER: CONNECTOR J3
Do not touch the peB edge-connectors, board components or the printed cir-
cuit cable without observing static-discharge precautions.
Handle the drive by
the frame only.
DC power is transmitted from the host to the drive via the power connector,
13. 13 is a4-pin
AMP "Mate-N-Lock" connector, AMP part number 350211-1,
mounted on the solder side of the PCB. The recommended mating connector
is
AMP part number 1-480424-0.
Applications using cable lengths less
than five feet, may use #18AWG wire and
AMP 61314-4 strip pins. For applications requiring cable lengths greater than
five feet,
#14AWG wire is recommended using AMP 61117-4 strip pins.
2.4 FRAME GROUNDING: LUG J10
110 is an AMP "Faston:' part number 61761-2. It is located on the casting be-
tween
and below the host/drive interface connectors. The recommended mat-
ing connector is
AMP part number 62187-2. Refer below to Figure 7.
@@@®0®0(2)
R~L<0 ~E (0) ~ î s; ~
1FAULT 1
NO L1FE
CONNECTION TEST
J9
SHUNT BLOCK
(MLG-01)
J3
10
J10
J9
SHUNT BLOCK
(MLC-01)
J2
SHUNT BLOCK
(MLC-oO)
ST212 PRODUCT MANUALIRev. B
FIGURE 7:
Host/Drive Interface
and Drive Configuration
SHUNT BLOCK
(MLC-OO)
16
15
14
13
12
11
10
9

The ST212 may be configured for specific system requirements. These options
are detailed in Sections 3.1 through 3.5.
3.0
DRIVE
CONFIGURATION DRIVE CONFIGURATION: SHUNT J9 (MLC-01) 3.1
J9 is a16-pin right-angle shunt located midway between JI and J2. Use the
provided shorting blocks to enable the DRIVE SELECT
Hnes and any required
option.
Figure 7illustrates J9 and indicates pin 1.
EarHer drives employed ashunt which required cutting the jumpers to enable
DRIVE SELECT.
To enable DS1, for example, cut DS2, DS3 and DS4. Refer
to
Figure 7.
DRIVE SELECT 3.2
The DRIVE SELECT Hne enables the controller to select and address the drive.
Pins
1-2 shorted enable ï>RIVE SELECT 1
Pins 3-4 shorted enable DRIVE SELECT 2
Pins
5-6 shorted enable DRIVE SELECT 3
Pins
7-8 shorted enable DRIVE SELECT 4
DAISY-CHAIN 3.2.1
Each drive in the chain must be selected as either DRIVE SELECT 1, 2, 3 or
4, so that only one DRIVE SELECT UNE activates adevice. The last drive
in the chain must have the 220/330
{} resistor termination pack installed on the
Main Control PCB.
FIGURE 8:
Daisy-chain
DRIVE 1
Configuration CONTROL BUS
J1
TERMINAlOR
PACK REMOVED
J2
CONTROU
DRIVE 2
STATUS
SIGNALS
J1
TERMINAlOR
J2
PACK REMOVED
DRIVE 3
DATA CABLE
J1
TERMINAlOR
DATA CABLE J2 PACK REMOVED
DATA SIGNALS DRIVE 4
DATA CABLE
J1 TERMINAlOR PACK
DATA CABLE INSTALLED
J2 AS SHIPPED
ST212 PRODUCT MANUAL/Rev. B
11

3.3 RADIAL
The Radial option is enabled by shorting pins 15 and 16 at the J9 shunt. Drives
configured to this option are always selected
and respond to ail control signais
issued
on the attached control cable. The 220/330 0resistor termination pack
must remain installed
on each radially-connected drive. Figure 9illustrates a
host/drive Radial interconnection.
FIGURE 9:
Radial Configuration
DRIVE 1
hCONTROL CABLE r
J1
~
l..-
TERMINAlOR PACK
'""'"'"' CONTROL CABLE INSTALLED
r-l
---f
r
J2
AS SHIPPED
~
CONTROU
STATUS
CONTROL DRIVE 2
SIGNALS
~ CABLE ':\--./ "--
r
r-lCONTROL ~
J1
TERMINAlOR PACK
_CABLE rINSTALLED
J2
AS SHIPPED
DRIVE 3
......,
L----e
J1
,...JDATA CABLE TERMINAlOR PACK
---e=
INSTALLED
.....,
J2
AS SHIPPED
DATA CABLE "-
DATA SIGNALS DRIVE 4
,.....J DATA CABLE L-I' "---C
J1
TERMINAlOR PACK
INSTALLED
H
DATA CABLE
r-
J2
AS SHIPPED
~
L
3.4 WRITE
FAULT
The WRITE FAULT signal is intemallylatched. Aselectable option is provided
to clear tbis latch. The standard configuration, with the shortingblock removed,
resets the WRITE
FAULT latch when WRITE GATE is dropped and reasserted
after the detected fault has been cleared. With pins
11 and 12 shorted, WRITE
FAULT latch is reset when DRIVE SELECT is dropped and reasserted after the
detected fault has been cleared.
3.5 LIFE TEST
This function is used during the manufacturing process and is Dot recommend-
ed for field use. When pins 9 and 10 are shorted, the stepper motor will con-
tinuously seek between Track 0and the maximum cylinder. When in this mode
the drive will ignore control signais sent via the interface.
12
ST212 PRODUCT MANUALIRev. B

4.0
CONTROL
INPUT SIGNALS
The control signaIs are of two types: those to be multiplexed in amultiple drive
system and those intended
to do the multiplexing.
The signaIs to be multiplexed are WRITE GATE, HEAD SELECT
2°, HEAD
SELECT 21
,
HEAD SELECT 22, HEAD SELECT 23, DIRECTION IN, and
STEP. These Hnes are terminated with aremovable 220/330 {} resistor pack.
The multiplexing signaIs are DRIVE SELECT l, DRIVE SELECT
2, DRIVE
SELECT
3, and DRIVE SELECT4. These Hnes are terminated in asingle flXed
220/330 {} resistor pack.
Control signaIs are transmitted across the driver/receiver combination illustrat-
ed
in Figure 10. Control input signaIs are activated in accordance with the fol-
lowing specifications:
True: 0.0 VDC to 0.4 VDC
at 1= -48 mAmp max.
FaIse: 2.5 VDC
to 5.25 VDC at 1=+250 JLAmp (open collector)
Termination: 220/330
{} resistor pack
FIGURE 10:
Control Signais
Driver/Receiver
Combination
7438
20 FT. MAX
FLAT CABLE OR TWISTED PAIR
HEAD SELECT 20, 21,22,234.1
These signaIs aIlow the selection of each Read/Write head in abinary code se-
quence. The
Hnes arenumbered 0through 3. HEADSELECT Hne 2° is theleast
significant
Hne. WhenaIl HEAD SELECT Hnes are high on the interface, Head
o is selected.
WRITE GATE 4.2
The active state of this signal, or low level, enables data to be written to the
disc and inhibits carriage motion
if WRlTE FAULT is active on the receipt of
the first Step pulse. When inactive, or high, this signaI enables data to be trans-
ferred from the drive
and enables Step pulses to move the heads. Heads may
not be switched while WRlTE GATE is active.
8T212 PRODUCT MANUAL/Rev. B
13