
S T 2 5 1 - 1    SEAGATE
NO MORE PRODUCED                                      Native|  Translation
                                                      ------+-----+-----+-----
Form                 5.25"/HH              Cylinders     820|     |     |
Capacity form/unform    43/   51 MB        Heads           6|     |     |
Seek time   / track  28.0/ 8.0 ms          Sector/track   17|     |     |
Controller           MFM / ST412           Precompensation 65535
Cache/Buffer               KB              Landing Zone      910
Data transfer rate    0.625 MB/S int       Bytes/Sector      512
                      0.625 MB/S ext
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            W     Altitude    km    -0.305  3.048| -0.305  9.144
       idle               W     Shock        g        10       |     40
       seek               W     Rotation   RPM      3600
       read/write    12.0 W     Acoustic   dBA
       spin-up            W     ECC        Bit
                                MTBF         h     100000
                                Warranty Month
Lift/Lock/Park     YES          Certificates     CSA,FCC,TUV,UL478,VDE        

**********************************************************************
                        L   A   Y   O   U   T
**********************************************************************
SEAGATE  ST251/ST277R  PRODUCT MANUAL  36035-003, REV.D

  +---------------------------------------------------------+
  |                                                         |XX
  |                                                         |XX J2
  |                                                         |XX
  |                                                         |XX1
  |                                                         |+-+1
  |                                                         || |J7
  |                                                         || |
  |                              Terminator   +-+           |+-+15
  |                              Resistor     | |           |XX
  |                              Pack         | |           |XX J1
  |                                           | |           |XX
  |                                           +-+           |XX
  |                                              JP1x x x   |XX
  |                                                   x x   |XX1
  |                                                   JP2   |
  |                                                         |XX Power
  |                                                         |XX J3
  +---------------------------------------------------------+



**********************************************************************
                      J   U   M   P   E   R   S
**********************************************************************
SEAGATE  ST251/ST277R  PRODUCT MANUAL 36035-003, REV.D

 Jumper setting
 --------------

 x = Jumper set at factory


      J7 is located between the J1 and J2 edge-connectors.

         +-- - - - --+ +------------------------+ +-- - --+
      J1 +-- - - - --+ |16 14 12 10  8  6  4  2 | +-- - --+ J2
         Edge-connector|15 13 11  9  7  5  3  1 | Edge-connector
                       +------------------------+
                                   J7

 J7   Drive select
 -----------------
     +-------------+-------+-------+-------+-------+
     |Drive Select | 8-7   | 6-5   | 4-3   | 2-1   |
     +-------------+-------+-------+-------+-------+
     |Drive 4      | CLOSED| OPEN  | OPEN  | OPEN  |
     |Drive 3      | OPEN  | CLOSED| OPEN  | OPEN  |
     |Drive 2      | OPEN  | OPEN  | CLOSED| OPEN  |
     |Drive 1      | OPEN  | OPEN  | OPEN  | CLOSED|
     +-------------+-------+-------+-------+-------+

 The Drive Select line enables the controller to select and adress
 the drive. Control cable interface options may use either a daisy-
 chain or radial configuration.


 J7  Factory Test Jumper
 -----------------------
 x    9-10  OPEN
      9-10  CLOSE  Actuator seeks continuously

 This is a test function used during the manufacturing process and is
 not recommended for field use.
 When pins 9-10 at J7 are shorted, the actuator will continuously seek
 between Track 0 and the maximum data cylinder, ignoring control
 signals sent via interface.


 J7 and JP1  Write fault Latch
 -----------------------------
 These options allow the user configure the Write Fault reset to
 specific system requirements using JP1 and J7.
 JP1 has three jumper pads, and is located adjacent to the 34-pin
 J1 connector. J7 is located midway between the PCB edge-connectors.

 JP1  1- 2  CLOSE  STANDARD: Write Fault will be cleared when Write
                   Gate is false. A Write Fault will only occur when
                   Write Gate is true.
      2- 3  CLOSE  LATCHED: This option will maintain Write Fault true
                   after Write Gates goes false and is recommended for
                   controllers that do not edge-detect Write Fault.

                   The latched operation has two configurations which
                   are provided at the J7 shunt, pins 11-12.

                   J7  11-12  OPEN   The Write Fault signal can only
                                     be cleared by an poer on/off
                                     cycle. Use of this option in con-
                                     junction with the DC-Unsafe op-
                                     tion is not recommended.
                   J7  11-12  CLOSE  The Write Fault signal can be
                                     cleared by deselecting the drive.
                                     When the drive is deselected, and
                                     the fault condition is correct,
                                     the Write Fault signal will be
                                     false.

                   When the Radial configuration jumper (pins 15-16 at
                   J7) is used, the drive is continuously selected and
                   requires a power on/off cycle to clear Write Fault.


 J7  Reserved
 ------------
     13-14         Reserved


 J7  Daisy-Chain/Radial Drive configuration
 ------------------------------------------
 x   15-16  OPEN   Daisy-Chain Mode
            CLOSE  Radial Mode

 Drives can be configured in either a daisy-chain or radial mode.
 Radially-selected drives are always selected (See Write Fault).

 The resistor termination pack must remain installed on any radially
 configured drive. In a daisy-chain configuration, the last drive in
 a chain must have the resistor termination pack installed.


 JP2  DC-Unsafe Option
 ---------------------
      (ST251 and ST277R only)
      JP2 has two jumper pads, and when a jumper is installed, a DC-
      unsafe condition will cause a Write Fault to be sent to the
      interface.


 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



**********************************************************************
                      I   N   S   T   A   L   L
**********************************************************************
SEAGATE  ST251/ST252/ST277R/ST278R  PRODUCT MANUAL 36035-003, REV.D

 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-
 tation.
 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.

 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.

 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
 system.

 Auto-Truncation
 ---------------
 The drive will enter the auto-truncation mode when:

 The the controller issues an excessive number of step pulses, which
 would place the read/write heads outward beyond Track 0 or inward
 beyond Track 910.

 The read/write heads are parked in the shipping zone (while power is
 continuously applied) and step pulses are subsequently issued.

 When the drive is in auto-truncation mode, it will ignore additional
 step pulses, take control of the actuator and recalibrate the heads
 to Track 0.

 Caution: If the controller is still issuing slow-step pulses after
          the drive issues Seek Complete from auto-truncation mode,
          the drive will:

          Reenter auto-truncation mode if Direction In is false

          Step the remaining cylinders if Direction In is true

 DC Power Requirements
 ---------------------
 Power may be applied or removed in any sequence without loss of data
 or damage to the drive. Voltage tolerance (incl. ripple):  5%

 Precompensation
 ---------------
 The drives are not require precompensation.

 FCC Verification
 ----------------
 WARNING: The ST251, ST252, ST277R and ST278R are devices that are
 intended to be contained solely within a personal computer or
 similar enclosure (not attached to an external device). As such,
 they are considered to be a subassembly even when individually mar-
 keted to the customer.
 As a subassembly, no Ferderal Communications Comission authorization,
 verification or certification of the device is required.



**********************************************************************
                      F   E   A   T   U   R   E  S
**********************************************************************
SEAGATE  ST251/ST252/ST277R/ST278R  PRODUCT MANUAL 36035-003, REV.D

 Media defect
 ------------
 A media defect is a read error when data, which has been correctly
 written, cannot be recovered within 16 retries.
 Any media defects are noted on the drive defect map. Locations are
 noted by head, cylinder and bytes from Index.

 ST251/ST252 Media Defect Specification
 There will be no more than forty-two (42) defects total per drive.
 Cylinders 0,1 and 2 are defect free.

 ST277R/ST278R Media Defect Specification
 There will be no more than sixty-five (65) defects total per drive.
 Cylinders 0 and 1 are defect free.

 Read/write Head Parking
 -----------------------
 The ST251, ST252, ST277R and ST278R automatically park the read/
 write heads in the shipping zone at power-down. All portions of the
 read/write heads park inboard of the maximum data cylinder. When
 power is applied, the heads will recalibrate to Track 0.

 The heads may also be parked by issung a seek command to any cylinder
 between 820 and 910 inclusive. When the heads are parked in this
 manner (with power continuously applied) and step pulses are
 subsequently issued, the drive will recalibrate to Track 0.

 Recording Method
 ----------------
 The ST251 and ST252 are designed for operation with the ST412
 interface with MFM encoding at 5.0 Mbits/sec. data transfer rate.
 Operation of an MFM drive with an RLL controller is not approved by
 Seagate and will void the drive warranty.

 The ST277R and ST278R are designed to operate with the ST412 Inter-
 face with Run Length Limited (2,7) encoding at 7.5 Mbits/sec. data
 transfer rate.

 UL/CSA Listing
 --------------
 The drives are 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.

 Reliability
 -----------
 MTBF      ST251, ST252     100.000 POH
           ST277R, ST278R    70.000 POH
 PM:                        Not required
 MTTR:                      30 Minutes
 Service Life:              5 Years


**********************************************************************
                      G   E   N   E   R   A   L
**********************************************************************
SEAGATE   SUPPORT SERVICES

 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.

 SeaNET
 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
 (ftp://ftp.seagate.com).

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


 SeaBOARD
 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
 SeaFAX
 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.


