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Hard Drive: SEAGATE: ST225N 21MB 5.25"/HH SCSI1 SE

S T 2 2 5 N    SEAGATE
NO MORE PRODUCED                                      Native|  Translation
Form                 5.25"/HH              Cylinders     615|     |     |
Capacity form/unform    21/   25 MB        Heads           4|     |     |
Seek time   / track  65.0/20.0 ms          Sector/track   17|     |     |
Controller           SCSI1 SINGLE-ENDED    Precompensation
Cache/Buffer               KB              Landing Zone      670
Data transfer rate          MB/S int       Bytes/Sector      512
                      1.500 MB/S ext ASYNC
Recording method     MFM                            operating  | non-operating
Supply voltage     5/12 V       Temperature *C        10 45    |    -40 60
Power: sleep              W     Humidity     %         8 80    |      5 90
       standby       16.8 W     Altitude    km    -0.305  3.048| -0.305  9.140
       idle               W     Shock        g        10       |     40
       seek               W     Rotation   RPM      3600
       read/write    35.0 W     Acoustic   dBA
       spin-up            W     ECC        Bit   32
                                MTBF         h     100000
                                Warranty Month
Lift/Lock/Park     NO           Certificates     CSA,UL478,VDE                



  |                                                      || |Parity
  |                                                      || |SCSI ID
  |                                                      |+-+
  |                                                 +-+  |XX J1
  |                                                 | |  |XX SCSI
  |                                                1+-+  |XX Interface
  |                                      Resistor   +-+  |XX Connector
  |                                      Terminator | |  |XX
  |                                      Packs     1+-+  |XX
  |                                                 +-+  |XX
  |                                                 | |  |XX
  |                                                1+-+  |XX
  |                                                      |
  |                                                      |XX Power
  |                                                      |XX J3



Jumper setting

J2 SCSI Bus Adress and Parity Check
Select the desired SCSI ID with Jumpers. Install the optional
P-Jumper to enable Parity.

      |SCSI ID| P  4  2  1 | Each drive must have a distinct adress
      +-------+------------+ (SCSI ID) on the bus. SCSI ID 7 is usu-
      |   0   | o  o  o  o | ally reserved for the SCSI host adapter.
      |   1   | o  o  o  x |
      |   2   | o  o  x  o | Jumpers are provided on the drive for se-
      |   3   | o  o  x  x | lecting the SCSI bus address. The micro-
      |   4   | o  x  o  o | processor accesses this information at
      |   5   | o  x  o  x | power-on sequence. If the SCSI address is
      |   6   | o  x  x  o | changed, the drive must be powered off
      |   7   | o  x  x  x | and on.
      +-------+------------+ SCSI bus termination is assumed to be ex-
                |            ternal to the drive. A typical drive is
                |            supplied with the resistor termination
                |            packs installed.
                +------- Parity Bit Option
                         Some host systems require parity bit checking
                         Install the P-Jumper to enable Parity
                         SOME EARLY VERSIONS OF THE ST225N DO NOT
                         OFFER THE PARITY OPTION!

 50-Pin SCSI Connector Pin Assignments
    Signal    Pin No.    Signal     Pin No.
    -DB(0)       2       Ground       28
    -DB(1)       4       Ground       30
    -DB(2)       6       -ATN         32
    -DB(3)       8       Ground       34
    -DB(4)      10       -BSY         36
    -DB(5)      12       -ACK         38
    -DB(6)      14       -RST         40
    -DB(7)      16       -MSG         42
    -DB(P)      18       -SEL         44
    Ground      20       -C/D         46
    Ground      22       -REQ         48
    Ground      24       -I/O         50
    Terminator  26

  Note: All odd pins, except pin-25 are connected to ground. Pin-25
        is not connected.

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



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.

The mounting screws must not exceed inside the mounting feet more
than 3.2 mm, measured from the outside surface of the foot.

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.

SCSI Interface
The ST225N has an integral SCSI-compatible controller. This embedded
controller performs all of the functions that were previously
implemented by an add-on, or "host supplied" controller. With the
controller onboard, the diagnostic capabilities of the drive are en-
hanced because the controller is able to optimize drive performance
and error recovery.

The embedded controller supports the SCSI interface as defined in the
ANSI X3T9.2/82-2 document. The interface hardware is capable of
transferring up to 1.5 Mbytes/sec. using asynchronous data transfer.
Devices on the SCSI Interface are daisy-chained together using a
common cable. Both ends of the cable are terminated. All signals on
the interface are common between devices.

 SCSI bus drivers
 The ST225N uses open collector drivers. All signals are terminated
 with 220  to +5 VDC and 330  to ground. The terminating resistors are
 removable for multi-drive configuration.
 For this measurements, SCSI bus termination is assumed to be external
 to the drive. A typical drive is supplied with the resistor termina-
 tion packs installed.

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

 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
 8  resistive load on the +12 V line and an equivalent 3  load on the
 +5 V line.

A 50-conductor flat cable or 25-conductor twisted pair cable is
required. The maximum cable length is 6 meters (19.7 ft). Each SCSI
bus connection may have a 0.1 meter (0.33 ft) maximum stub length.

The characteristic impedance for unshielded flat or twisted pair
ribbon cable should be 100 10%. A characteristic impedance greater
than 90 is preferred for shielded cables.
To minimize discontinuities and signal reflections it is desirable
to minimize the use of cables of different impedances in the same

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 certification of the device is

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

Disc format
The ST225N disc format is flexible and supports either 256, 512, 532
or 1024 bytes/sector.

    Guaranteed Megabytes      22.57     20.89     21.36     20.13
    Bytes per Sector        1024       532       512       256
    Sectors per Track          9        16        17        32

Head Park Zone
This drive employs a parking zone. The read/write heads may be parked
by issuing a seek to any cylinder between 615-670. At power-on the
drive will recalibrate to Track 0. If the heads are parked while
power is still applied, any step pulse will cause the unit to recali-
brate to Track 0.

Record interleave
The ST225N supports user-specified record interleaves from 1:1
(records formatted sequntially on the disk) through the number of
records per track minus 1. This gives the user the ability to confi-
gure the drive for maximum performance within the operating environ-

Onboard Drive Diagnostics
At power-on the drive will execute a series of diagnostic tests. Any
failure will be indicated by a series of LED (front panel) flashes.
The first failure will be preserved. The drive is ready to read/write
if no error codes are received within 20 seconds.

 |Flashes|Failures codes                                           |
 |   1   |Microprocessor/Internal Memory Test                      |
 |   2   |Microprocessor ROM Checksum Test                         |
 |   3   |Controller Chip Test                                     |
 |   4   |Controller Program RAM Test                              |
 |   5   |Dat Buffer RAM Test                                      |
 |   6   |Spindle Speed Test                                       |
 |       | If the drive is unable to reach and maintaine correct   |
 |       | spindle speed                                           |
 |   7   |Read Record ID Mark                                      |
 |       | If the controller is unable to find and read an ID mark |
 |       | for any record                                          |
 |   8   |Read Operating System Microcode From Drive               |
 |       | If the controller is unable to read the operating system|
 |       | from the drive                                          |

Offline Self-test Routines
To enable the test, short the following pins to ground at the SCSI
connector: 2, 12, 16 and 32.

The self test has three parts. They will cycle in order until power
or a ground jumper is removed, or until ten complete passes.

The LED will remain ON during the test and will turn OFF if an error
is detected or a jumper is removed. The LED will flash continuously
if 10 passes are completed without error.

PART ONE: All sectors in the user data area are read starting with
logical block zero.
PART TWO: This is a butterfly read/seek test. Starting at the center
of the user data tracks, the unit will seek outward and inward by in-
crements until the limits of the user data tracks are reached. A one
track read is performed to verify position.
PART THREE: This part performs a write/read compare on all sectors of
the diagnostic cylinders using the data pattern 6DBh.
The diagnostic cylinders are located at an inner region on each media
surface. Any unrecoverable errors will terminate the test and turn
off the LED.

Incoming inspection
The ST225 supports a self-test routine that SEAGATE recommends for
incoming inspection. This test may be run after the unit has sucess-
fully passed the power-on diagnostics.



Formating and Defect Management
Media defects are identified and recorded on the disc during the
manufacturing process. This defect map is used during formatting
and enables the drive to bypass these defects. During the formatting
operation, the controller uses sector-slip technique to reassign
defective sectors.

Sector-slip allows any sector with a defect to be mapped and
bypassed. The next contiguous sector is given that sector address.
The ST225N support three variations of the format command:

  - Format using a combined list of previously defined defects
    (manufactires's list plus user-defined list)

  - Format with previously defined list plus additional user-
    defined defects

  - Format with manufacturer's list only (removes all user-defined

The defect list contains a four-byte header followed by one or more
defect descriptors. The length of the defect descriptor is four

Access Time Definition and Timing
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 5-200 sec.

                                          | ST225N |
        Track-to-Track         msec.      |  20    |
                       Average msec.      |  65    |
        Full-Stroke            msec.      | 150    |

Recording Method
The ST225N has an integral SCSI interface controller, employing MFM
data encoding. When installed in systems designed to interface
directly with SCSI peripherals, no additional hardware is required.
However, some installations may require device driver software.

UL/CSA Listing
The St225N drive 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.

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