Seagate ST251R User manual

ST251/ST251 RIST277R
Product
Manual
February 3, 1987
36035-001, Revision A
920 Disc Drive, Scotts Valley, CA 95066-4544, USA
Telephone:
408/438-6550. Telex: 176455 SEAGATE SCVL
c5S» seagate

Copyright Notice
This manual and all the material contained in
it are copyrighted with
all rights reserved. This manual may not be copied, in whole
or in
part, without written consent of Seagate Technology.
Seagate reservesthe rightto change, without notice, thespecifications
contained
in this manual.
ii
ST251 1251 RI277R Product Manual, Rev.A

CONTENTS
1.0 SPECIFICATION SUMMARY ...................... 1-1
1.1 Drive Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1.1 Unformatted Capacity ...................... 1-1
1.1.2 Formatted Capacity . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1.3 Physical Organization. . . . . . . . . . . . . . . . . . . . . . 1-1
1.2 Access Time Definition and Timing. . . . . . . . . . . . . . . . . 1-2
1.3 Step Pulse Period and Seek Method. . . . . . . . . . . . . . . . 1-2
1.4 Functional Specifications. . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1.S Recording Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1.6 Physical Specifications .......................... 1-3
1.7 Reliability Specifications. . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1.7.1 Read Error Rates . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1.7.1.1 Bit
Jitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1.7.2 Media
Defects. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
1.7.2.1 ST2S1 .............................. 1-S
1.7.2.2 ST2S1R ....... , . . . . . . . . . . . . . . . . . . . . . 1-S
1.7.2.3 ST277R . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 1-S
1.8 Environmental Specifications ..................... 1-S
1.8.1 Ambient Temperature ...................... 1-S
1.8.1.1 ST251 .............................. 1-S
1.8.1.2 ST251R/277R ........................ 1-5
1.8.2 Temperature Gradient . . . . . . . . . . . . . . . . . . . . . . 1-5
1.8.3 Relative
Humidity. . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
1.8.4 Altitude Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
1.8.S Shock and Vibration Specifications. . . . . . . . . . . . 1-6
1.8.S.10peratingShock ........... .......... 1-6
1.8.S.2 Operating Vibration. . . . . . . . . . . . . . . . . . . 1-6
1.8.5.3 Nonoperating Shock
.................. 1-7
1.8.5.4 Nonoperating Vibration . . . . . . . . . . . . . . . . 1-7
1.9 DC Power Specifications. . . . . . . . . . . . . . . . . . . . . . . . . 1-8
1.9.1 Input Noise Ripple and Frequency ............ 1-10
1.9.2 ULlCSA Certification. . . . . . . . . . . . . . . . . . . . . . . 1-10
1.10
FCC Certification .............................. 1-10
1.11 Mounting Requirements. . . . . . . . . . . . . . . . . . . . . . . . . 1-11
1.11.1 Shock Mounti ng Recommendations .......... 1-11
ST251 /251 RI277R Product Manual, Rev.A iii

1.11.2 Handling Precautions. . . . . . . . . . . . . . . . . . . . . . 1-13
1.11.3 Shipping
Zone............ ..... ......... . 1-13
1.12
Auto-Truncation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
1.13 Typical Drive Timing
........................... 1-14
2.0 DRIVE CONFIGURATION. . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.1 Drive Configuration Shunt J7 . . . . . . . . . . . . . . . . . . . . . . 2-1
2.2 Drive Select .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.2.1 Daisy-Chain/Radial Drive Configurations ..... . . 2-2
2.3 Write
Fault Latch Options: JP1 and J7 . . . . . . . . . . . . . . . 2-2
2.4 DC-Unsafe Option: JP2
.......................... 2-3
2.5 Precompensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2.6 Life-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
APPENDIX A. MFM/RLL FORMAT EXAMPLE. . . . . . . . . . . . A-1
iv ST251
1251 RI277R Product Manual, Rev.A

LIST OF ILLUSTRATIONS
Figure 1. Typical + 12 VDC Start-Up Current Profile ...... 1-9
Figure
2. Typical Power-On Sequence ................. 1-9
Figure
3. Drive Mounting Dimensions. . . . . . . . . . . . . . . . . . 1-12
Figure
4. Read/Write Timing. . . . . . . . . . . . . . . . . . . . . . . . . 1-14
Figure
5. Buffered-Seek Timing. . . . . . . . . . . . . . . . . . . . . . . 1-15
Figure
6. Auto-Truncation Timing. . . . . . . . . . . . . . . . . . . . . 1-15
Figure
7. Host/Drive Interface Connectors .............. 2-1
ST251 /251RI277R Product Manual, Rev.A v

vi
ST251 1251 RI277R Product Manual, Rev.A

INTRODUCTION
This manual supports the ST251 1251 R/277R discdrives. It supercedes
and replaces the
ST251 Product Manual, 36016-001, Rev. B.
ST251 1251 RI277R Product Manual, Rev.A
vii

viii ST251 /251R/277R Product Manual, Rev.A

1.0 SPECIFICATION SUMMARY
1.1 DRIVE CAPACITY
1.1.1 UNFORMATTED CAPACITY
ST251 ST251R ST277R
Megabytes Per Drive: 51.2 51.2 76.9
Bytes Per Cylinder: 62,496 62,496 93,744
Bytes Per Track: 10,416 15,624 15,624
1.1.2 FORMATTED CAPACITY
Megabytes Per Drive: 42.8 43.6 65.5
Bytes Per Cylinder: 52,224 53,248 79,872
Bytes Per Track: 8,704 13,312 13,312
Bytes Per Sector: 512 512 512
Sectors per Track: 17 26 26
1.1.3 PHYSICAL ORGANIZATION
Tracks: 4,920 3,280 4,920
Cylinders: 820 (0-819) 820 (0-819) 820 (0-819)
Read/Write Heads: 6 4 6
Discs: 3 2 3
ST251 /251R/277R Product Manual, Rev.A
1-1

1.2 ACCESS TIME DEFINITION AND TIMING
Access time is defined as the time from the leading edge of the first
step pulse received to Seek Complete (including settling). All seek
times are
true statistical averagesand are calculated with a step pulse
period of 10 psec.
at nominal power and temperature.
Track-to-Track:
Average:
Full-Stroke:
Average Latency:
8 msec. max.
40 msec. max.
95 msec. max.
8.33 msec.
1.3 STEP PULSE PERIOD AND SEEK METHOD
The step signal is a 2psec. minimum width pulse which initiates read/
write head motion. The step pulse period determines the access
method. The number of pulses determines the seek length. The step
pulse period must
be between 3/lsec. and 200/lsec.
Steppulses may be lostatperiodsgreaterthan 200jJsec. Foradditional
information on step pulses and seek methods consult the Seagate
ST412
Interface Manual.
1-2 ST251 1251 RI277R Product Manual, Rev.A

1.4 FUNCTIONAL SPECIFICATIONS
ST251 ST251R ST277R
Rotational Speed: 3,600 RPM ±0.5%
Recording Density: 9,935 BPI 14,902 BPI 14,902 BPI
Flux Density: 9,935 Fel 9,935
Fel
9,935 Fel
Track Density: 777 TPI 777 TPI 777 TPI
Interface: 8T412 ST412 ST412
Recording Method: MFM RLL (2,7) RLL (2,7)
Data Transfer Rate: 5.0 Mbits/sec. 7.5 Mbits/sec. 7.5 Mbits/sec.
1.5 RECORDING METHODS
The 8T251 is designed to operate with the 8T412 interface with MFM
encoding at 5.0 megabit/sec. data
transfer rate.
Caution: Operation of an MFM
drive with an RLL controller Is not ap-
proved by Seagate.
The 8T251R and 8T277R are designed
to operate with the 8T412 in-
terface with Run Length Limited (2,7) encoding at 7.5 megabit/sec.
data transfer rate.
1.6 PHYSICAL SPECIFICATIONS
Height:
Width:
Depth:
Weight:
1.63 inch. max. (41.4 mm)
5.77 inch. max.
(146.1 mm)
8.00 inch. max. (203.2 mm)
2.75Ibs. (1.25 Kg.)
8T2511251 R/277R Product Manual, Rev.A 1-3

1.7 RELIABILITY SPECIFICATIONS
MTBF:
PM:
MTTR:
Service life:
1.7.1 READ ERROR RATES
Recoverable Read Errors:
Nonrecoverable Read Errors:
Seek Errors:
1.7.1.1 BIT JITTER
20,000 Power-on hours
(Sea level, 25°C ambient temp.)
Not required
30 minutes
5 years
1 per
10
10 bits read
1 per
10
12 bits read
1 per
10
6 seeks
Bit
jitter reduction determines the relationship between the leading
edge of
read data and the center of the data window.
The specified read
error rates are based on the following bit jitter
specifications: 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.
1.7.2 MEDIA DEFECTS
A mediadefect is a read error when the data, which has been correctly
written, cannot
be recovered within 16 retries.
A printout will be provided with each drive shipped listingthe locations
of any defect by head, cylinder, sector and byte. It will also specify
the
number of bytes from index. For MFM this will be based on 1.6
psec.lbyte. RLL encodi ng is based on 1.056psec.lbyte.
A single media defect may be up to 16 bits long. Cylinders 0,1,2 and
3
will be free of defects.
1-4
ST2511251 RI277R Product Manual, Rev.A

1.7.2.1 ST251
There will be no more than forty-two (42) defects total per drive.
1.7.2.2 ST251R
There will be no more than forty-three (43) defects total per drive.
1.7.2.3 ST277R
There will be no more than sixty-five (6S) defects total per drive.
1.8 ENVIRONMENTAL SPECIFICATIONS
1.8.1 AMBIENT TEMPERATURE
1.8.1.1 ST251
Operating:
Nonoperating:
1.8.1.2 ST251 R/277R
Operating:
Nonoperating:
1Qoe to 4soe (SOoF to 113°F)
-400e to 60° (-40°F to 140°F)
1soe to 4soe (S9°F to 113°F)
-400e to 60° (-400F to 140°F)
1.8.2 TEMPERATURE GRADIENT
Operating:
Nonoperating:
10
o
e/hr. (18
oF/hr.) max.
Below condensation
ST2511251RI277R Product Manual, Rev.A
1-S

1.8.3 RELATIVE HUMIDITY
Operating:
Maximum Wet Bulb:
Nonoperating:
8 to 80% noncondensing
26°C (78.8°F)
5 to 90% noncondensing
1.8.4 ALTITUDE LIMITS
Operating: -1,000 ft to 10,000 ft
Nonoperating: -1,000 ft to 30.000 ft
1.8.5 SHOCK AND VIBRATION SPECIFICATIONS
All shock and vibrationspecificationsassumethatthe drive is mounted
in an approved orientation with the input levels at the
drive mounting
screws.
Shock measurements are based on a
11 msec. half-sine wave shock
pulse. The nonoperating specifications assume that the read/write
heads are positioned in the shipping zone.
1.8.5.1 OPERATING SHOCK
Maximum shock without incurring physical damage or degradation in
performance:
10 G's.
1.8.5.2 OPERATING VIBRATION
Maximum vibration, at the following frequencies, without incurring
physical damage or degradation in performance:
1-6
Freq.
5-22 Hz:
22-300 Hz:
300-22 Hz:
22-5
Hz:
Vibration
0.010 in. Displacement (double amplitude)
0.25 G Acceleration (peak)
0.25 G Acceleration (peak)
0.010 in. Displacement (double amplitude)
ST251/251RI277R Product Manual, Rev.A

1.8.5.3 NONOPERATING SHOCK
Maximum shock without incurring physical damage or degradation in
performance:
40 G'S.
1.8.5.4 NONOPERATING VIBRATION
Maximum vibration, at the following frequencies, without incurring
physical damage or degradation in performance:
Freq.
5-22 Hz:
22-300 Hz:
300-22 Hz:
22-5 Hz:
Vibration
0.020 in. Displacement (double amplitude)
0.50 G Acceleration (peak)
0.50 G Acceleration (peak)
0.020 in. Displacement (double amplitude)
ST251 /251 R/277R Product Manual, Rev.A 1-7

1.9 DC POWER SPECIFICATIONS
Power may be applied or removed in any sequence without loss of
data or damage to the drive.
Typical seeking/nonseeking current and powerspecifications assume
nominal voltages applied, 25°C ambient temperature, sea level and
spindle rotating.
Typical seek currents are measured on a buffered one-third stroke
seek followed by two revolutions of non-seek time.
Maximum (3 sigma max.) seeking/nonseeking current specifications
assume 10° C ambient temperature, 5.25
VDC and 12.6 VDC applied,
sea level and spindle rotating.
Maximum seek currents are measured
on repetitive 3-track buffered
seeks with a one-half spindle rotation between each seek.
+12 VDC
Voltage Tolerance (inc. ripple):
Max. Current at Power-Up:
Seeking Current:
Nonseeking Current:
+5VDC
Voltage Tolerance (inc. ripple):
Seeking Current:
Nonseeking Current:
POWER
Seeking:
Nonseeking:
±5% both seek and nonseek con-
ditions
2.0 Amps
1.8 Amps max. Peak
1.1 Amps max. RMS
0.7 Amps typo RMS
0.7 Amps max. RMS
0.5 Amps typo RMS
±5% both seek and nonseek con-
ditions
1.4 Amps max. Peak
1.1 Amps max. RMS
0.9 Amps typo RMS
1.3 Amps max. RMS
1.0 Amps typo RMS
13 Watts typo
11 Watts typo
1-8 ST2511251R1277R
Product Manual, Rev.A

FIGURE 1: Typical + 12 VDC Start-Up Current Profile
1,63A
f·
- ~- -
I
i i
I 1,14A
SECONDS
FIGURE 2: Typical Power-On Sequence
~ ...
-,
1,03A
+5VDC
4SA +12 VDC
rr rr
_--_);1---------1))1------------
DC ON
I- 12 sec. 1yp. ---.j r
ROTATIONAL SPEED ~I------------
REGULATED ±O.S% (
)
r--10 sec. typo ---.j
- TRACK"
~ .J~~ __________ __
------------)~.J~----~ l
-READY 20
msec, max.H
-
---------~(,..(-----I(,..(------~
).1 }.;
-SEEK COMPLETE 5
msec. max, H
------------)~~,..(----~,c,..(------~
1"141-----------25 sec, max·-----~ .. I
ST2511251 RI277R Product Manual, Rev.A 1-9

1.9.1 INPUT NOISE RIPPLE AND FREQUENCY
The maximum permitted noise ripple is 100 mV (peak-to-peak) mea-
sured
at the host system power supply across an equivalent 8 n re-
sistive load
on the + 12 Volt line and an equivalent 3 n load on the
+5 Volt line. The maximum permitted inputnoisefrequency is 20 MHz.
1.9.2 UL/CSA CERTIFICATION
The ST251 islisted in accordancewith UL 478 andCSA C22.2 (O-M 1982),
and meets all applicable sections of IEC 380 and VDE 0806/08.81, as
tested by TUV-Rheinland,
North America.
1.10 FCC CERTIFICATION
WARNING
The ST251 is certified to comply with the limitsfor a Class B computing
device, pursuant to Subpart J of Part
15 of FCC rules. Only devices
certified to comply with the Class B limits may be attached to this
peripheral. Operation with non-certified devices is likely to result in
interference to radio and television reception.
Radio and Television Interference
This equipment generates and uses radio frequency energy and if not
installed and used instrictaccordance with the manufacturer's instruc-
tions, may cause interference to radio and television reception.
1-10
ST2511251RI277R Product Manual, Rev.A

It has been type tested and found to comply with the limits for a Class
B computing device peripheral in accordance with the specifications
in Subpart J of Part
15 of FCC rules, which are designed to provide
reasonable protection against such interference in a residential instal-
lation. However, there is no guarantee that interference
will not occur
in a
particular installation. If this equipment does cause interference
to radio
or television, which can be determined by turning the equip-
ment on and off, you are encouraged to try one
or more of the following
corrective measures:
• Reorient the receiving antenna.
• Move the device to one side or the other of the radio or TV.
• Move the device farther away from the radio or TV.
• Plug the computer into a different outlet so that the receiver and
computer are on different branch outlets.
If necessary you should consult your dealer or an experienced radiol
television technician for additional suggestions. You may find helpful
the following booklet prepared by the Federal Comunications Com-
mission: How to Identify and Resolve Radio-Television Interference
Problems. This booklet is available from the Superintendent of Docu-
ments, U.S. Government Printing Office, Washington,
DC 20402. Refer
to publication
number 004-000-00345-4.
1.11 MOUNTING REQUIREMENTS
The drive may be mounted horizontally with the PC Board down or on
either side. Mounting vertically on either end is a prohibited orienta-
tion. Refer to Figure 3 on
page 1-12 for mounting dimensions.
The
drive should not be tilted front or back, in any position, by more
than 5°. For optimum performance the
drive should be formatted in
the same position as it
will be mounted in the host system.
1.11.1 SHOCK MOUNTING RECOMMENDATIONS
It is recommended that any external shock mounts between the drive
and the host frame be designed so that the composite system has a
ST251 1251 RI277R Product Manual, Rev.A 1-11

vertical resonant frequency of 25 Hz or lower. A minimum clearance
of 0.050 inches should be allowed around the entire perimeter of the
drive to allow for cooling airflow and motion during mechanical shock
or vibration. I
FIGURE 3: Drive Mounting Dimensions
1'95! 010
(495 ± 25)
5e75 + 010
('49 22- ± 25~
I
_ 1.87 + .03 f-
(47.50 ±.76tl
3.12 .t 03
(79.25 ,16)
NOTE: The mounting screws must not extend
Inside the mounting feet more than
0.125 inch,
measured from the outside surface of the foot.
I
~
I
;
I
I
b
Mounting Foot
S.77 mall.
1'466)
Oulside Surlace
1-12
ST2511251 RI277R Product Manual, Rev.A