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Hard Drive: SEAGATE: ST157A-1 45MB 3.5"/HH IDE / AT

S T 1 5 7 A - 1    SEAGATE
NO MORE PRODUCED                                      Native|  Translation
Form                 3.5"/HH               Cylinders     560| 1024|  733|
Capacity form/unform    45/   58 MB        Heads           6|    5|    7|
Seek time   / track  28.0/ 8.0 ms          Sector/track   26|   17|   17|
Controller           IDE / AT              Precompensation
Cache/Buffer               KB              Landing Zone
Data transfer rate    0.938 MB/S int       Bytes/Sector      512
                      4.000 MB/S ext
Recording method     RLL 2/7                        operating  | non-operating
Supply voltage     5/12 V       Temperature *C        10 50    |    -40 60
Power: sleep              W     Humidity     %         8 80    |      5 90
       standby            W     Altitude    km    -0.305  3.048| -0.305  9.144
       idle               W     Shock        g        10       |     60
       seek               W     Rotation   RPM      3600
       read/write     9.0 W     Acoustic   dBA        40
       spin-up            W     ECC        Bit
                                MTBF         h     150000
                                Warranty Month
Lift/Lock/Park     YES          Certificates     CSA,FCC,IEC435,TUV,UL478,VDE 



  |                                  10-pin version  10--+  |
  |                                                   |J2|  |
  |                                   6-pin version   6  |  |
  |                                                   |  |  |XX 40 PIN
  |                                                   +--1  |XX C
  |                                                         |XX O
  |                                                         |XX N
  |                                                         |XX N
  |                                                         |XX E
  |                                                         |XX C
  |                                                         |XX T
  |                                                         |XX O
  |                                                         |XX R
  |                                                         |XX1
  |                                                         |
  |                                                         |XX Power
  |                                                         |XX J3
  +---------------------------------------------------------+  1



Jumper setting

 J2  Drive configuration 6-pin version
       |                                     |2  4  6|
       |                                     +-------+
       |                                     |o  o  o|
       |                                     |*  o  o|
       | Single drive                        |X      |
       |                                     |       |
       | Dual-drive master                   |X  X   |
       |                                     |       |
       | Dual-drive slave                    |   X   |
       |                                     |       |
       | (Optional) Drive Activity Indicator |      X|

  J2  External LED 6 pin version
      pin 5-6  CLOSE  External LED option enabled
               OPEN   External LED option disabled

  J2  Drive configuration 10-pin version
       |                                     |2  4  6  8 10|
       |                                     +-------------+
       |                                     |o  o  o  o  o|
       |                                     |*  o  o  o  o|
       | Single drive                        |   X         |
       |                                     |             |
       | Dual-drive master                   |   X  X      |
       |                                     |             |
       | Dual-drive slave                    |             |
       |                                     |             |
       | (Optional) Drive Activity Indicator |            X|
       |                                     |             |
       | Reserved position                   |X        X   |
           1-2 and 7-8 reserved positions. Do not use !!!

  J2  Master/Slave configuration
     Configure up to drives on a single AT bus (table below).

     Drive Type            | Master    |Slave Present
     Only drive in system  | Installed |Removed
     Drive 1 in a two drive| Installed |Installed
     system                |           |
     Drive 2 in a two drive| Removed   |Removed
     system                |           |

     Up to two drives can be daisy-chained (Master/Slave) on the same
     host bus.

 J2  External LED 10 pin version
     pin 9-10  CLOSE  External LED option enabled
               OPEN   External LED option disabled

Remote LED: When pins 9 and 10 on the User Configuration jumper block
are shorted drive will indicate activity to the system via a connec-
tor on the host adapter or motherboard.

 J3   DC Power and pin connector assignments
      +------------+   pin 1    +12 VDC
      | 1  2  3  4 |   pin 2    +12 Volts Return
      +------------+   pin 3    + 5 Volts Return
                       pin 4    + 5 VDC


SEAGATE ST125A/138A/157A PRODUCT MANUAL 36110-001/2, REV.C

Notes on installation

Drive mounting

     horizontally             vertically
   +-----------------+   +--+             +--+ +------------------+
   |                 |   |  +-----+ +-----+  | |                  | x
   |                 |   |  |     | |     |  | x+----------------+x
 +-+-----------------+-+ |  |     | |     |  | ||x              x||
 +---------------------+ |  |     | |     |  | ||  x          x  ||
                         |  |     | |     |  | ||    x      x    ||
      x           x      |  |     | |     |  | ||      x  x      ||
 +------x------x-------+ |  +-----+ +-----+  | ||       xx       ||
 +-+------x--x-------+-+ +--+             +--+ ||     x    x     ||
   |       xx        |                         ||   x        x   ||
   |     x    x      |                         || x            x ||
   +---x--------x----+                         |x                x|
     x            x                           x++----------------++x
      UNACCEPTABLE!                                UNACCEPTABLE!
      Never install PC board on the Top!

The drive may be mounted horizontally with the PC board down or on
either side. Mounting vertically on either end is a prohibited orien-
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.

AT Interface Connector Requirements
The drive connector is a 40-conductor connector with 2-rows of 20
male pins on 100 mil centers.
The mating cable connector is a 40-conductor nonshielded connector
with 2-rows of 20 female contacts on 100 mil centers.

Translation/Native Mode Selection
The drive(s) will always power-up in their respective default
Translation modes.

Virtual Emulation
The drive will support any 17-sector-based disc geometry as long as
the number of logical heads is 16, the number of logical cylinders
is 1,024 and the resulting number of sectors does not exceed the
drive's total guaranteed sector count.

 Input Noise
 Maximum permitted input noise ripple: 100 mV (peak-to-peak)
 Maximum permitted input noise: 20 MHz.
 Ripple measured at the host system power supply across an equivalent
 20  resistive load on the +12 V line and an equivalent 8  load on the
 +5 V line.

Shock and vibrations
All shock and vibration specifications assume that the drive is moun-
ted in an approved orientation with the input levels at the drive
mounting screws.

Shipping Zone
When the read/write heads are positioned in the shipping zone, all
portions of the head/slider assembly park inboard of the maximum data

The read/write heads automatically move to the shipping zone at

The read/write heads may be parked by issuing a seek command to any
cylinder between 614 and 666.

When power is applied, the heads will recalibrate to Track 0. If the
heads are parked while power is applied, any step pulse will cause
the unit to recalibrate to Track 0.

FCC Verification
These drives are devices which are intended to be contained solely
within a personal computer or similar enclosure and not attached to
an external device. As such, they are considered to be subassemblies
even when individually marketed to the customer.
As a subassembly, no Federal Communications Commission authorization,
verification or certification of the drive is required.
Seagate Technology, Inc. has tested these devices in an enclosure as
described above to ensure that the total assembly (enclosure, disk
drive, motherboard, power supply, etc.) does comply with the limits
for a Class B computing device. Operation with non-certified assem-
blies is likely to result in interference to radio and television

DC Power specifications
Power may be applied or removed in any sequence without loss of data
or damage to the drive, except during a write operation. Typical
current and power specifications assume nominal voltages applied,
25*C ambient temperature, sea level and spindle rotating.
Voltage tolerance (incl. ripple): 5%

Handling and Static-Discharge Precautions
After unpacking, and prior to system integration, the drive may be
exposed to potential handling and ESD hazards. It is mandatory that
you observe standard static-discharge precautions. A grounded wrist-
strap is preferred. Handle the drive by the frame only and always
rest the drive on a padded surface until it is mounted in the host

When transporting or shipping a drive, a Seagate-approved container

Supported System BIOS revisions
The system will report the BIOS type and version number on a cold
boot. The ST125A, ST138A and ST157A are AT interface compatible
drives. The BIOS manufacturers listed below have indicated that the
referenced BIOS revisions are fully compatible with the IBM AT Task
File Interface specifications.

Earlier BIOS revisions may provide only partial AT support. Compati-
bility problems may include repeated drive access errors or system
timeout errors.

     | AMI         | Dated 4/9/90 or later             |
     | Award       | Version 3.04 or higher            |
     | Quadtel     | Single Drive System: Any Version  |
     |             | Dual Drive System: 3.04 or higher |
     | Phoenix     | BIOS Plus 286: 3.10 or higher     |
     |             | BIOS Plus 386: 1.10 or higher     |
     | PhoenixBIOS | Version 1.00 or higher            |

CMOS Configuration
Seagate AT interface drives mimic (translate) other drive geometries.
If none of the drive types offered by the CMOS supports the numbers
of heads, cylinders and sectors shown by the table, and your system
does not support a "user defined" drive type, then select a drive
type in your systems CMOS with a capacity which is less than or equal
to the capacity of the drive.

When specifying drive geometry to the system CMOS, different values
may be used for the cylinders, read/write heads and sectors/track
than those given below. However, the final drive capacity shown by
the CMOS cannot exceed the capacity of the drive.

After the drive has been properly configured for the system, and the
correct drive type has been specified to the system CMOS, the drive
should be low-level formatted.

Low Level Formatting
Seagate AT Interface drives are low-level formatted at the factory
and do not require low-level formatting!

A drive can be subdivided into "partitions", which behave as indivi-
dual drives within the system. Earlier versions of DOS have a limi-
tation on maximum drive capacity and consequently require high capa-
city drives to be divided into smaller partitions. For DOS users,
each partition will be assigned a different letter, i.e., C: and D:
for a drive with two partitions.

Drive partitioning in DOS is done by using the FDISK utility. After
the drive has been configured, defined in CMOS and low-level format-
ted (if necessary), the user must boot the system to the floppy drive
with a bootable DOS diskette. The user must then run the FDSIK util-
ity to partition the drive. Refer to your DOS manual for instruction
on using FDISK.

Many UNIX based operating systems allow partitioning of the drive for
use by DOS applications. In UNIX, drive formatting and partitioning
are both done by a single operating system utility. Refer to your
system documentation for instructions.

High level formatting
High-level formatting verifies the information written by the low-
level format and establishes drive access information used by the
operating system.
High-level formatting in DOS creates the File Allocation Table used
by DOS for all drive access. The high-level format is initiated in
DOS by the FORMAT command.
High-level formatting in UNIX creates the I-NODE used by the system
for file access information. In UNIX, drive formatting and partitio-
ning are both done by a single operating system utility.



Media Defects
A media defect is a read error when the data, which has been
correctly written, cannot be recovered within 16 retries.
A label is fixed to the drive listing the location of any media
defects by cylinder, head and bytes from index. For MFM encoding,
this is based on 1.6 sec./byte. AT interfaces drives have the
controller onboard. This allows bad sectors to mapped out; thereby
transparent to the user. Seagate specifies gurabteed megabytes for
ST157 family AT interface drives.

AT Interface
This drive family uses the industry-standard IBM AT task file
interface. It support both 8 and 16-bit data transfer and has no DMA
All data transfers are done via programmed I/O.

 AT Interface Connecter Pin Assignments
      pin     signal        I/O  | pin     signal        I/O
      01      /Host Reset    O   | 21      Reserved      O
      02      Ground             | 22      Ground
      03      Host Data  7   I/O | 23      /HIOW         O
      04      Host Data  8   I/O | 24      Ground
      05      Host Data  6   I/O | 25      /HIOR         O
      06      Host Data  9   I/O | 26      Ground
      07      Host Data  5   I/O | 27      Reserved
      08      Host Data 10   I/O | 28      Host ALE      O
      09      Host Data  4   I/O | 29      Reserved
      10      Host Data 11   I/O | 30      Ground
      11      Host Data  3   I/O | 31      IRQ14         I
      12      Host Data 12   I/O | 32      Host IO16     I
      13      Host Data  2   I/O | 33      Host ADDR 1   O
      14      Host Data 13   I/O | 34      /PDIAG         Notes
      15      Host Data  1   I/O | 35      Host ADDR 0   O
      16      Host Data 14   I/O | 36      Host ADDR 2   O
      17      Host Data  0   I/O | 37      /Host CSO     O
      18      Host Data 15   I/O | 38      /Host CS1     O
      19      Ground             | 39      /Host SLV/ACT Notes
      20      Key                | 40      Ground

       * /Indicates active low signal
       * Direction is with respect to the host
       * I indicates to the host, O indicates from the host
       * Reserved pins/ground do not have direction
       * /PDIAG and HOST/SLAVE are used for communication between
         Master and Slave drive
       * Pin-1 is referenced in LAYOUT. It may also be located by the
         square solder pad on the PC board.

 AT Bus Signal Levels
 Signal driven by the drive must have the following output character-
 istics at the drive connector:
                                Logic Low:      0 to 0.4  VDC
                                Logic High:   2.5 to 5.25 VDC

 Signal received by the drive must have the following input character-
 istics, measured at the drive connector:
                                Logic Low:      0 to 0.8  VDC
                                Logic High:   2.0 to 5.25 VDC

Seek Time Definition and Timing
Seek time is a true statistical average (at least 5,000 measure-
ments) of the time to execute the seek, less overhead.
All measurements assume a block size of 512 bytes, nominal voltages,
25*C ambient temperature and sea level.
Track-to-track seek time is the average of all possible single-
track seeks in both directions. Average seek time is measured by
executing seek in both directions between random cylinders or Logi-
cal Block Addresses (LBA). Full-stroke seek time is one-half the
time needed to seek from LBA zero to the maximum LBA and back to LBA

                                          | ST1**A |
        Track-to-Track         msec. typ. |   8    |
                               msec. max  |  10    |
                       Average msec. typ. |  28    |
                       Average msec. max. |  30    |
        Full-Stroke            msec. typ. |  70    |
                               msec. max. |  75    |
        Latency                msec. avg. |   8.33 |

DC Power Specifications
Power may be applied or removed in any sequence without loss of data
or damage to the drive.

Bit Jitter
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 -40dB of
bit jitter reduction at 2F with an offset of less than 1.5 nsec.
shift from the center of the data window.

UL/CSA Listing
The St157 drive family is listed in accordance with UL 478 and CSA
C22.2 (0-M1982), and meets all applicable sections if IEC 380 and
VDE 0806/08.81, as tested by TUV-Rheinland, North America.



Seagate Technology
Technical Support Services
If you need assistance installing your drive, consult your dealer.
Dealers are familiar with their unique system configurations and can
help you with system conflicts and other technical issues. If you
need additional assistance with your Seagate(r) drive or other
Seagate products, use one of the Seagate technical support services
listed below.

SeaFONE at 1-800-SEAGATE (1-800-732-4283)
Seagate's 800 number allows toll-free access to automated self-help
services, providing answers to commonly asked questions,
troubleshooting tips and specifications for disc drives and tape
drives. This service is available 24 hours daily and requires a
touch-tone phone. If you need to speak to a technical support
engineer, dial this number and listen to the options for technical
support. (International callers can also reach this automated
self-help service by dialing 408-456-4496).

Seagate Technology online services
Using a modem, you can obtain troubleshooting tips, free utility
programs, drive specifications and jumper settings for Seagate's
entire product line. You can also download software for installing
and analyzing your drive.

You can obtain technical information on Seagate drives, Seagate
software and much more over the Internet from Seagate's World Wide
Web home page (http://www.seagate.com) or Seagate's ftp server

You may also send E-mail with your questions to DiscSupport@
Seagate.com or TapeSupport@Seagate.com.

SeaBOARD is a computer bulletin board system (BBS) that contains
information about Seagate's disc and tape drive products and is
available 24 hours daily. Set your communications software to eight
data bits, no parity and one stop bit (8-N-1). SeaBOARD phone numbers
are listed in the following table.

BBS Location Modem number
United States Disc: 408-434-1080; Tape: 408-456-4415
England 44-1628-478011
France 33 1-48 25 35 95
Germany 49-89-140-9331
Singapore 65-292-6973
Thailand 662-531-8111
Australia 61-2-9756-2359
Taiwan 886-2-719-6075

Seagate CompuServe forum
Online technical support for Seagate products is available on
CompuServe. To access our technical support forum, type go seagate.
This forum provides information similar to that found on SeaBOARD.
In addition, you can type questions or browse through previous
questions and answers on the forum messages.

Seagate Technology FAX services
You can use a touch-tone telephone to access Seagate's automated FAX
system to receive technical support information by return FAX. This
service is available 24 hours daily.
Location Telephone number
United States 1-800-SEAGATE or 408-456-4496
England 44-1628-894084
Australia 61-2-9756-5170

Seagate technical support FAX
You can FAX questions or comments to technical support specialists 24
hours daily. Responses are sent during business hours.
Location FAX number
United States 408-944-9120
England 44-1628-890660
France 33 1-46 04 42 50
Germany 49-89-1430-5100
Australia 61-2-9725-4052
Singapore 65-293-4722
Hong Kong 852-2368 7173
Taiwan 886-2-715-2923
Korea 82-2-556-7294/4251

Seagate technical support
You can talk to a technical support specialist during business hours
Monday through Friday for one-on-one technical help. Before calling,
note your system configuration and drive model number (STxxxx). There
are several technical support phone numbers available for various
Seagate products.

 Location          Telephone  number
 United States Please dial 1-800-SEAGATE for the specific product
               telephone number.
               (6:00 A.M. to 11:15 A.M., 12:30 P.M. to 5:00 P.M.,
               Pacific time, M-F)
 England       44-1628-894083 (10:00 A.M. to 1:00 P.M., 2:00 P.M. to
               5:00 P.M., M-F)
 France        33 1-41 86 10 86 (9:30 A.M. to 12:30 P.M., 2:00
               P.M. to 5:00 P.M., M-F)
 Germany       Disc: 49-89-140-9332; (9:30 A.M. to 12:30 P.M., 2:00
               P.M. to 4:00 P.M., M-F)
               Tape: 49-89-140-9333
 Australia     61-2-9725-3366 (9:00 A.M. to 5:00 P.M., M-F)
 Singapore     65-290-3998 (9:00 A.M. to 12:00 P.M., 2:00
               P.M. to 5:00 P.M., M-F)
 Hong Kong     852-2368 9918
 Taiwan        886-2-514-2237
 Korea         82-2-556-8241

SeaTDD 408-944-9121
Using a telecommunications device for the deaf (TDD), you can send
questions or comments 24 hours daily and exchange messages with a
technical support specialist between 6:00 A.M. to 11:15 A.M. and
12:30 P.M. to 5:00 P.M. (Pacific time) Monday through Friday.

Customer Service Centers
Seagate direct OEM, Distribution, System Integrator and Retail
customers should contact your Seagate Service Representative for
warranty information. Other customers contact your place of
purchase. Seagate offers comprehensive customer support for all
Seagate drives. Seagate customer service centers are the only
facilities authorized to service Seagate drives. These services are
available worldwide.

Location Telephone number FAX number
United States 1-800-468-3472; 405-949-6740
Other Americas
(Canada & Brazil) 405-949-6706; 405-949-6738
Mexico 525-546-6965; 525-546-4888
Europe, Middle
East & Africa 31-2065-43300; 31-2065-34320
Asia Pacific &
Australia 65-485-3595; 65-485-4980
Japan 81-3-5462-2904; 81-3-3462-2979

Seagate, Seagate Technology and the Seagate logo are registered
trademarks of Seagate Technology, Inc. SeaFAX, SeaFONE, SeaBOARD,
SeaTDD, SeaNET, Medalist and DiscWizard are either trademarks or
registered trademarks of Seagate Technology, Inc. or one of its
subsidiaries. All other trademarks or registered trademarks are the
property of their respective owners.

previous page: Hard Drive: SEAGATE: ST157A-0 38MB 3.5"/HH    IDE / AT
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