W R E N   V H H   9 4 2 2 1 - 2 0 9 M    IMPRIMIS
NO MORE PRODUCED                                      Native|  Translation
                                                      ------+-----+-----+-----
Form                 5.25"/HH              Cylinders    1544|     |     |
Capacity form/unform   179/  209 MB        Heads           5|     |     |
Seek time   / track  18.0/ 4.0 ms          Sector/track     |     |     |
Controller           SCSI1 MAC             Precompensation
Cache/Buffer            32 KB              Landing Zone
Data transfer rate    1.875 MB/S int       Bytes/Sector      512
                      4.700 MB/S ext SYNC
Recording method     RLL 2/7                        operating  | non-operating
                                                  -------------+--------------
Supply voltage     5/12 V       Temperature *C        10 50    |    -40 70
Power: sleep              W     Humidity     %         8 80    |      5 95
       standby            W     Altitude    km    -0.305  3.048| -0.305 12.210
       idle          16.0 W     Shock        g         2       |     32
       seek               W     Rotation   RPM      3600
       read/write         W     Acoustic   dBA
       spin-up            W     ECC        Bit
                                MTBF         h      40000
                                Warranty Month
Lift/Lock/Park     YES          Certificates     CSA,FCC,IEC380,UL478,VDE



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                        L   A   Y   O   U   T
**********************************************************************
SEAGATE  ST2125N/2209N  PRODUCT MANUAL 77765297-D

  +---------------------------------------------------------+
  |                                   Terminator +--------+ |XX J1
  |                                   Connector  |  (3)   | |XX Power
  |                                   Mount PWA  +--------+ |xx
  |                                   (Visable from bottom) |+-+
  |                                                         || |J2
  |                                                         |+-+
  |                                                         |++
  |                                                         |||J4
  |                                                         |||
  |                                                         |++
  |                                                         |XX Inter-
  |                                                         |XX face
  |                                                         |XX J3
  |                                                         |XX
  |                                                         |XX
  |                                                         |XX
  +---------------------------------------------------------+



**********************************************************************
                      J   U   M   P   E   R   S
**********************************************************************
SEAGATE  ST2125N/ST2209N  PRODUCT MANUAL 77765297-D

 Jumper setting
 ==============


  J2 SCSI ID/Parity Check
  -----------------------
           +------------+
           | o  o  o  o |
           | o  o  o  o |
           +------------+
             4  2  1  P(2)

      +------------+----------+
      |            | 4  2  1  |
      +------------+----------+  Drive ID in binary coded jumper
      |SCSI ID = 0 | o  o  o  |  position (most significant bit on
      |            | o  o  o  |  left), i.e., jumper in position 1
      +------------+----------+  would be Drive ID 1, no jumpers means
      |SCSI ID = 1 | o  o  x  |  ID 0.
      |            | o  o  X  |
      +------------+----------+
      |SCSI ID = 2 | o  x  o  |
      |            | o  X  o  |
      +------------+----------+
      |SCSI ID = 3 | o  x  x  |
      |            | o  X  X  |
      +------------+----------+
      |SCSI ID = 4 | x  o  o  |
      |            | X  o  o  |
      +------------+----------+
      |SCSI ID = 5 | x  o  x  |
      |            | X  o  X  |
      +------------+----------+
      |SCSI ID = 6 | x  x  o  |
      |            | X  X  o  |
      +------------+----------+
      |SCSI ID = 7 | x  x  x  |
      |            | X  X  X  |
      +------------+----------+

 (2)  CLOSED  Parity checking by the WREN V HH is enabled.



 J4 Terminator Power/Test Seek
 -----------------------------

     Position A
    +--------------------------------------+
 (3)| o    o    xxxxxxx   o    o    o    o |
    +--------------------------------------+
        J3-26   TP  +5V        TST  GRD  M

     Position B
    +--------------------------------------+
 (3)| o    xxxxxxx   o    o    o    o    o |
    +--------------------------------------+
        J3-26   TP  +5V        TST  GRD  M

     Position C
    +--------------------------------------+
 (3)| xxxxxxx   o    o    o    o    o    o |
    +--------------------------------------+
        J3-26   TP  +5V        TST  GRD  M

 (3) Jumper in position A means terminator power (+5V) for the
     internal terminators is from the WREN V HH power connector.

     Jumper in position B means terminator power for the internal
     terminators is taken from the interface cable, pin 26. If the
     I/O cable is removed with a jumper in position B and with the
     internal terminators installed, the drive will not power up.

     If a jumper is installed in position C the WREN V HH will supply
     terminator power to pin 26 of the interface cable. [Note: If a
     jumper is installed in position C a jumper must also be installed
     in Position A to power the internal terminators.

 If unit is not to be terminated, remove the terminator resistor
 packs. Removal of terminator power source select jumper does not
 disconnect the terminator resistor from the circuit.


     Motor Start Option
    +--------------------------------------+
 (4)| o    o    o    o    o    o    xxxxxx |
    +--------------------------------------+
        J3-26   TP  +5V        TST  GRD  M

 (4) CLOSED   Enable Motor Start Option. In this mode of operation the
              drive will wait for a Start Unit Command from the Host
              before starting the Motor.
     OPEN     The Motor will starts as soon as DC power is applied to
              the unit.


     Test Seek Jumper
    +--------------------------------------+
 (5)| o    o    o    o    o    xxxxxxx   o |
    +--------------------------------------+
        J3-26   TP  +5V        TST  GRD  M

 (5) With the jumper in this position the unit will continuously
     perform test seeks to random cylinders. Motor starts as soon as
     DC power is applied.




 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


 Note: Pins on the drive select and configuration select header are
 provided to facilitate manual drive configuration. No devices other
 than jumpers should be connected to these pins. Connection
 to external devices (switches, connectors, etc.) could adversely
 affect drive performance. Exact location of these pins and headers
 may change without notice.



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                      I   N   S   T   A   L   L
**********************************************************************
SEAGATE  ST2125N/ST2209N  PRODUCT MANUAL 77765297-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!


 Drive Orientation
 -----------------
 Only two WREN V HH mounting orientations are permitted: disk in the
 horizontal plane and disks in the vertical plane. Horizontal
 mounting with the front  (non I/O cable end) raised as much as 15*
 above the horizontal is acceptable. Mounting with either end down
 (front or rear) or upside down is not permissible.

 WREN V HH is designed, manufactured, and tested with a "Plug-in and
 Play" installation philosophy. This minimizes the requirements for
 highly trained personnel to integrate the WREN 6 HH into an OEM's
 system, wether in a factory or field environment.

 Mounting Holes
 --------------
 Mounting Holes (6-32 UNC-28). Four on bottom, four on each side. Max.
 screw length into chassis 0.25 in. (6.35 mm).

 Cooling
 -------
 Cabinet cooling must be designed by the customer so that the ambient
 temperature immediately surrounding the WREN V HH will not exceed
 temperature conditions. Specific consideration should be given to
 make sure adequate air circulation is present around the PWAs at the
 rear of the drive.

 Service Tools
 -------------
 No special tools are required for site installation or recommended
 site maintenance. The depot repair philiosophy of WREN V HH precludes
 the necessity for special tools. If field repair of items external to
 the HDA is desired, a 6 point Torx T8 and T10 drivers are required.
 It may be purchased through most commercial tool catalogs.

 Physical Description
 --------------------
 Model 94221 WREN V HH may be daisychained together or with other
 compatible SCSI devices using a common cable. Both ends of the cable
 must be terminated. The WREN V HH implements single ended drivers and
 receivers, which allow a maximum cable length of six metres
 (primarily for connection within a cabinet). All signals are common
 between all SCSI devices. The Model 94221 WREN V HH may be
 daisychained only with SCSI devices with single ended drivers and
 recovers. A maximum of 8 SCSI devices (including the Host) may be
 daisychained together. The SCSI Devices at both ends of the
 daisychain are to terminated. Intermediate SCSI devices shall not be
 terminated. For drives that are not to be terminated, remove the
 terminator resistor packs, not the terminator power source selector
 jumper.

 Cable Requirements
 ------------------
 Only nonshielded cable connectors are applicable. A 50 conductor flat
 cable or 25 twisted pair cable shall be used. The maximum total cable
 length shall be 6.0 metres. A stub length of no more than 0.1 metre
 is allowed off the mainline interconnection within any connected
 equipment. An ideal impedance match with cable terminators implies a
 cable characteristic impedance of 132 ohm (single ended option). In
 general, cables with this high of a characteristics impedance are not
 available; however, impedances that are somewhat lower are satis-
 factory. A characteristic impedance of 100 ohm   10% is recommended
 for unshielded flat or twisted pair ribbon cable. However, most
 available cables have a somewhat lower characteristic impedance. To
 minimize discontionuities and signal reflections, cables of different
 impedances should not be used in the same bus. Implementations may
 require trade-offs in shielding effectiveness, cable length, the
 number of loads, transfer rates, and cost to achieve satisfactory
 system operation. If shielded and unshielded cables are mixed within
 the same SCSI bus, the effect of impedance mismatch must be carefully
 considered.

 A minimum conductor size of 28 AWG should be used to minimize noise
 effects.

 Suggested nonshielded flat cable part numbers are:

    Flat cable     3M-3365-50
    Twisted pair   Spectra twist in flat 455-248-50

 Equivalent parts may be used.

 Connector Requirements
 ----------------------
 The nonshielded cable connector shall be a 50 conductor connector
 constisting of to rows of 25 female contacts with adjacent contacts
 100 mils apart.

 Recommended Mating Flat Cable Connector Part Numbers are:

 Closed end   3M-3425-7000      W/O Strain Relief, No Center Key
 (for cable   3M-3425-7050      With Strain Relief, No Center Key
 ends)        Dupont-66900-290  With Strain Relief, With Center Key

 Open end     3M-3425-6000      W/O Strain Relief, No Center Key
 (In Daisy-   3M-3425-6050      With Strain Relief, No Center Key
 chain)       Dupont-66900-250  With Strain Relief, With Center Key

 The Model 94221 WREN V HH device connector is a nonshielded 50
 conductor connector consisting of two row of 25 male pins with
 adjacent pins 100 mils apart. The connector is keyed.

 Drive Connector Part Number: DuPont 78963-001 or equivalent.


    +--------------SCSI-DEVICE-----------------+
    |       +--+ HOST ADAPTER/INITIATOR ***    |
    |       |T |                               |
    +-------++-+-------------------------------+
            *|
             |
             |                1 thru 8 SCSI devices
             +---------------+--------------+
           **|             **|              |*
    +--------+---+ +---------+--+ +--------++-++
    |WREN        | |WREN        | |WREN    | T||
    |or other    | |or other    | |or other+--+|
    |SCSI device | |SCSI device | |SCSI device |
    +------------+ +------------+ +------------+

 *    Closed end type connector used
 **   Open type (in-line application) Connector used.
 ***  Host need not be on the end of the daisy chain. Another device
      can be on the end with the terminator, the host having no
      terminator.

 T indicates termination required.

 DC Cable and Connector
 ----------------------
 The WREN V HH receives DC power through a 4 pin right angle connector
 mounted on the servo PWA. Recommended part number for the mating
 connector are listed below, but equivalent parts may be used.

 Type of cable:      14 AWG
 Connector:          AMP 1-480424-0
 Contacts:           AMP 60619-4 (Loose Piece); AMP 61117-4 (Strip)

 Electrical Description
 ----------------------
 All interface signals with the Model 94221 WREN V HH are single ended
 and must be terminated with 220 ohm to +5 V and 330 ohm to ground at
 each end of the total cable. All signals use open collector or three
 state drivers. Optional termination is available internal to the WREN
 V HH.

 Single Ended Drivers/Receivers
 ------------------------------
 Single ended drivers and receivers are used by the WREN V HH.

 Transmitter Characteristics
 ---------------------------
 The WREN VHH uses an ANSI SCSI compatible open collector single ended
 driver. This driver is capable of sinking a current of 48 mA with a
 low level output voltage of 0.4 volt.

 Receiver Characteristics
 ------------------------
 The WREN V HH uses a ANSI SCSI single ended receiver with hysteresis
 gate or equivalent as a line receiver.

 Terminator Requirements
 -----------------------
 Internal WREN V HH I/O termination consist of three resistor modules
 which plug into sockets on the Main PWA. The WREN V HH may be ordered
 with or without these termination resistors to facilitate a
 particular application. All single initiator/single target (non-
 daisychain) applications require that the Initiator and WREN V HH be
 terminated. Daisychain applications require that only the unit at
 each end of the daisychain be terminated. All other peripherals on
 the chain should not be terminated.

 Note: Remove terminator resistor packs where terminators are not
 required. Removal of terminator power source selection jumper does
 not disconnect the terminator resistor from the circuit. The 330 ohm
 resistor to ground still affects the circuit operation.

 Drive Termination
 -----------------
 This option may be incorporated during manufacture at the request of
 the customer. Termination consists of three 220/330 ohm resistor
 modules which are installed on the Main PWA via sockets. The user
 may install or remove these as desired.


 Terminator Power
 ----------------
 The WREN V HH may be configured to accept terminator power via Pin 26
 of the SCSI bus or to provide terminator power for optional internal
 termination resistors via the WREN V HH power connector.The WREN V HH
 can also be configured to supply terminator power to Pin 26 o the
 SCSI bus via an isolation diode.
 Single ended SCSI devices providing termination power (TERMPWR) shall
 have the following characteristics:

     V TERM = 4.0V to 5.25V
     800 mA min source drive capability
     1.0 A maximum


 AC/DC Ground Separation
 -----------------------
 The 94221 WREN V HH is provided with the DC/HDA logic ground and
 chassis tied together. An option is provided permitting the user to
 isolate the ground planes by repositioning the "U" shaped grounding
 washer. This option may be beneficial in reducing ground induced
 noise in some system applications.



**********************************************************************
                      F   E   A   T   U   R   E  S
**********************************************************************
SEAGATE  ST2125N/2209N  PRODUCT MANUAL 77765297-D

 General Description
 -------------------
 The WREN V HH is a member of a family of low cost, high performance,
 highly reliable, random access storage devices designed to meet the
 needs of the OEM marketplace.

 Standards
 ---------
 The WREN V HH has been developed as a system peripherals to the
 highest standards of design and construction. The WREN V HH depends
 upon its host equipment to provide adequate power and environment in
 order to achieve optimum performance and compliance with applicable
 industry and governmental regualations. Special attention must be
 given in the areas of safety, power distribution, shielding, audible
 noise control, and temperature regulation.

 The WREN V HH complies with Seagate standards.

 The WREN V HH is a UL Recognized component per UL 478 and a CSA
 Certified component per CSA C22.2 No. 154-M1983. It also meets the
 requirements of DIN IEC 380/VDE 0806/8.81.

 The WREN V HH as delivered, is designed for system integration before
 use. It is supplied as a Class A Computing Device per the FCC Rules
 and the Regulations, Part 15, Subpart J governing EMI of computing
 devices and the Radio Interference Regulations of the Canadian
 Department of Communications.

 The Head/Disc/Actuator Assembly (HDA) is environmentally sealed at
 the factory. Air is recirculated within the HDA through a nonreplace-
 able filter to maintain a contamination free disc/actuator
 environment.

 The WREN V HH uses a dedicated landing zone at the innermost radius
 of the media thus eliminating the possibility of destroying or
 degrading data by landing in the data zone.

 The WREN V HH incorporates an automatic shipping look which prevents
 potential damage to the heads and discs caused by movements during
 shipping and handling. The shipping lock is automatically disengaged
 when power is applied to the drive.

 The WREN V HH decodes Track 0 location from the dedicated servo
 surface thereby eliminating mechanical transducer adjustments and
 related reliability concerns.

 The WREN V HH uses a high performance actuator assembly
 consisting of a low inertia, balanced, patented, straight arm design
 which provides excellent performance with minimum power dissipation.

 The WREN V HH uses the Zone Bit Recording (ZBR TM) version of
 variable track capacity recording, an advanced recording technique
 that oprimize the recording media utilization. The ZBR technology
 results in increased performance due to the higher transfer rates
 associated with the outer data tracks. Reliability is also improved
 by reducing the number of disks necessary to obtain the required
 capacity.


 Media Description
 -----------------
 The media used on the WREN V HH has a diameter of approximately 5
 inches (130 mm). The aluminum substrate is coated with a thin film
 magnetic material, overcoated with a proprietary protective layer for
 improved durability and environmental protection.

 Defect and Error Management
 ---------------------------
 WREN V HH, as delivered, complies with this specification. The read
 error rate and specified storage capacity are not dependent upon use
 of defect management routines by the host (initiator).

 Defect and error management in the SCSI system involves WREN V HH
 internal defect/error management and SCSI systems error
 considerations (errors in communications between Initiator and WREN
 V HH). Tools for use in designing a defect/error management plan are
 briefly outlined in this section, with references to other sections
 where further details are given.


 WREN V HH Internal Defects/Errors
 ---------------------------------
 Identified defects are recorded on the WREN V HH defects list tracks
 (referred to as the promary or ETF defect list). It is recommended
 that these known defects be reallocated during the initial WREN V HH
 format operation. The WREN V HH internal retries and data correction
 by ECC should be enabled to recover data from additional flaws if
 they occur. If data correction by ECC is required to recover data,
 the host should immediately reallocate this sector by use of the
 Reassign Blocks command. If the WREN V HH automatic retries and data
 correction by ECC features are not used, defects are usually un-
 recoverable and need to be reallocated as they are diacovered. For
 reallocation of bad sectors, the number of spare sectors per track or
 cylinder and the number of spare tracks per volume is programmable.
 After formatting, defects can be automatically reallocated by the
 WREN V HH, or can be reallocated when the host sends the Reassign
 Blocks Command.


 Seek Time
 ---------
                    Without Controller Overhead

                                          | 209 MB  | 184 MB  |
        ----------------------------------+---------+---------+
        Track-to-Track         msec. typ. |   4     |    4    |
                               msec. max. |   6     |    6    |
                       Average msec. typ. |  18     |   16.5  |
                       Average msec. max. |  20     |   18.5  |
                               msec. max. |  40     |   38    |
        Latency                msec. avg. |   8.33  |    8.33 |
        ----------------------------------+---------+---------+


                    Including Controller Overhead

                                          | 209 MB  | 184 MB  |
        ----------------------------------+---------+---------+
        Track-to-Track         msec. typ. |   4.6   |    4.6  |
                               msec. max. |   6.6   |    6.6  |
                       Average msec. typ. |  18.6   |   17.1  |
                       Average msec. max. |  20.6   |   19.1  |
                               msec. max. |  40.7   |   38.7  |
        Latency                msec. avg. |   8.33  |    8.33 |
        ----------------------------------+---------+---------+


 Read Look-Ahead/Cache Control
 -----------------------------
 The WREN V HH Model 94221 provides a selectable Read Look-ahead
 buffering algorithm which can in may cases enhance
 system performance. This feature may be selected by issuing a Mode
 Select Command with the Enable/Disable Cache bit set in the Cache
 Control page.


 Power Sequencing
 ----------------
 Power sequencing is not required for the WREN V HH. The WREN V HH
 protects against inadvertent writing during power up and down.
 Daisychain operation requires that power be maintained on the
 terminated WREN V HH to ensure proper termination of the peripheral
 I/O cables.


 Start/Stop Time
 ---------------
 After DC power has been applied, the WREN V HH will become ready
 within 20 seconds if the Motor Start Option is disabled. During this
 time, the drive will respond to the SCSI interface. Stop time will be
 less than 25 seconds from removal of DC power.

 If the Motor Start Option is enabled, the internal controller will
 accept a Motor Start, Test Unit Ready, Inquiry or Request Sense
 Command via the sCSI interface 3 seconds after DC power has been
 applied.

 After the Motor Start Command has been received the WREN V HH will
 become ready for normal operations within 20 seconds. During this
 time the drive will respond to the SCSI interface.

 There is no power control switch on the drive.


 Temperature
 -----------
 50* to 122* F (10* to 50* C) Operating Ambient with a maximum
 gradient of 18* F (10* C) per hour. Above 1000 feet (305 metres)
 altitude the maximum temperature is derated linearly to 112*F
 (44.4*C) at 10,000 feet (3048 metres). Cabinet packaging designs must
 provide ample air circulation around the WREN V HH to ensure
 environmental limits are not exceeded as a result of heat transfer
 from other system components. Operating Ambient for specification
 purposes is defined as the environment immediately surrounding the
 WREN V HH. The temperature of the HDA is restricted to a maximum of
 142*F (61.4* C) during operation.

 Air Cleanliness
 ---------------
 The WREN V HH is designed to operate in a typical office environment
 with minimal environmental control.

 Reliability
 -----------
 The following reliability specifications assume correct host/drive
 operational interface, including all interface timings, power supply
 voltages, environmental conditions and environmental requirements.

 MTBF                     40,000 hours
 Service Life             5 years
 Preventive Maintenance   None required