
W R E N   I I   9 4 1 5 5 - 1 2 0 P    IMPRIMIS
NO MORE PRODUCED                                      Native|  Translation
                                                      ------+-----+-----+-----
Form                 5.25"/FH              Cylinders     960|     |     |
Capacity form/unform   102/  120 MB        Heads           8|     |     |
Seek time   / track  28.0/ 5.0 ms          Sector/track   26|     |     |
Controller           RLL / ST506           Precompensation   128
Cache/Buffer               KB              Landing Zone
Data transfer rate    0.938 MB/S int       Bytes/Sector      512
                      0.938 MB/S ext
Recording method     RLL                            operating  | non-operating
                                                  -------------+--------------
Supply voltage     5/12 V       Temperature *C        10 45    |    -40 70
Power: sleep              W     Humidity     %        20 80    |      5 95
       standby            W     Altitude    km    -0.305  3.048| -0.304 12.192
       idle          28.0 W     Shock        g         2       |     32
       seek               W     Rotation   RPM      3564
       read/write         W     Acoustic   dBA
       spin-up            W     ECC        Bit
                                MTBF         h      40000
                                Warranty Month
Lift/Lock/Park     YES          Certificates     CSA,SDA,FCC,IEC380,IEC435,...

**********************************************************************
                        L   A   Y   O   U   T
**********************************************************************
SEAGATE  ST4135R  PRODUCT MANUAL 77765324-C


  REAR
    +------------------------------------------------------------+
    |                                                            |
    |                                                            |
    |Drive                                                       |
    |Select    Terminator                                        |
    | +----+   +--------+      Control Cable            Power  AC|
    +-+----+---+--------+------XXXXXXXXXXXXXXXXXXXX----XXXXXXX--x+
    |                                                            |
    |        Data Cable                                          |
    +--------XXXXXXXXXXXXXXX-------------------------x------x----+
    |                                              W3        W4  |
    +------------------------------------------------------------+


 AC = Quick Connect Terminal




**********************************************************************
                      J   U   M   P   E   R   S
**********************************************************************
SEAGATE  ST4135R  PRODUCT MANUAL 77765324-C

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

 x = Jumper setting at factory


 J1   WREN Interface
 -------------------
                  Signal Direction    Signal Direction
   +-----------+                                      +-------------+
   |           |                                      |Signal Ground|
   |           | Head Select  2(3)                    |No.    No.   |
   |           +------------------------------------->|  2     1    |
   |           | Head Select  2(2)                    |             |
   |           +------------------------------------->|  4     3    |
   |           | Write Gate                           |             |
   |           +------------------------------------->|  6     5    |
   |           | Seek Complete                        |             |
   |           |<-------------------------------------+  8     7    |
   |Controller/| Track 0                              |             |
   |Host       |<-------------------------------------+ 10     9    |
   |Interface  | Write Fault                          |             |
   |           |<-------------------------------------+ 12    11    |
   |           | Head Select  2(0)                    |             |
   |           +------------------------------------->| 14    13    |
   |           | Reserved  to J2 pin 7                |             |
   |           +--------------------------------------+ 16    15    |
   |           | Head Select  2(1)                    |             |
   |           +------------------------------------->| 18    17    |
   |           | Index                                |             |
   |           |<-------------------------------------+ 20    19    |
   |           | Ready                                |             |
   |           |<-------------------------------------+ 22    21    |
   |           | Step                                 |             |
   |           +------------------------------------->| 24    23    |
   |           | Drive Select 1                       |             |
   |           +------------------------------------->| 26    25    |
   |           | Drive Select 2                       |             |
   |           +------------------------------------->| 28    27    |
   |           | Drive Select 3                       |             |
   |           +------------------------------------->| 30    29    |
   |           | Drive Select 4                       |             |
   |           +------------------------------------->| 32    31    |
   |           | Direction In                         |             |
   |           +------------------------------------->| 34    33    |
   |           |                                      |             |
   +-----------+                                      +-------------+
                                                       WREN Control
                                                       Cable Connector

   All signals in the control cable are single ended signals.

 Pin 2 in the control cable is defined as Reduced Write Current in the
 Seagate ST412 interface. The WREN 2 controls write current internally
 and thus the line is not needed for this function and is used instead
 for the fourth head select line.

 Note that this is a potential incompatibility with existing drives
 and controllers and applies to the WREN 2 (RLL) in its full capacity
 versions only: Models 94155-135 (9 Data Heads, 135 MB). Reduced
 capacity WREN 2 (RLL) models ignore the Reduced Write Current/Head
 Select 2(3) signal line, pin 2.



 J2   DC 506 Interface
 ---------------------
                  Signal Direction    Signal Direction
   +-----------+                                      +-------------+
   |           |                                      |Pin No. Type*|
   |           | Drive Selected                       |             |
   |           |<-------------------------------------+  1      SE  |
   |           | Ground                               |             |
   |           +--------------------------------------+  2          |
   |           | Reserved                             |             |
   |           +--------------------------------------+  3      SE  |
   |           | Ground                               |             |
   |           +--------------------------------------+  4          |
   |Controller/| Motor On (OPTION)                    |             |
   |Host       +--------------------------------------+  5      SE  |
   |Interface  | Ground                               |             |
   |           +--------------------------------------+  6          |
   |           | Reserved  to J4 Pin 16               |             |
   |           +--------------------------------------+  7          |
   |           | Ground                               |             |
   |           +--------------------------------------+  8          |
   |           | Reserved                             |             |
   |           +--------------------------------------+  9          |
   |           | Reserved                             |             |
   |           +--------------------------------------+ 10          |
   |           | Ground                               |             |
   |           +--------------------------------------+ 11          |
   |           | Ground                               |             |
   |           +--------------------------------------+ 12          |
   |           | +RLL Write Data                      |             |
   |           +------------------------------------->| 13      DIFF|
   |           | -RLL Write Data                      |             |
   |           +------------------------------------->| 14      DIFF|
   |           | Ground                               |             |
   |           +--------------------------------------+ 15          |
   |           | Ground                               |             |
   |           +--------------------------------------+ 16          |
   |           | +RLL Read Data                       |             |
   |           |<-------------------------------------+ 17      DIFF|
   |           | -RLL Read Data                       |             |
   |           |<-------------------------------------+ 18      DIFF|
   |           | Ground                               |             |
   |           +--------------------------------------+ 19          |
   |           | Ground                               |             |
   |           +--------------------------------------+ 20          |
   |           |                                      |             |
   +-----------+                                      +-------------+
                                                       Data Cable
                                                       Connector

 * SE   = Single Ended Signal
   DIFF = Differential Signal


 Remote Motor Start
 ------------------
 The WREN 2 (RLL) will support remote start control capability via a
 user specified option. This option utilized a reserved line on the
 data cable (pin number 5) to enable the motor ON routine in the
 drive. If this option is not selected, Pin 5 will be open and non-
 functional. If this option is installed, Pin 5 will start the spindle
 concurrent with an asserted (high) low level.


 Drive Select Jumper
 -------------------

           +---+---+---+---+---+
           | o | o | o | o | o |
           | o | o | o | o | o |
           +-+-+-+-+-+-+-+-+-+-+
             |   |   |   |   +------  Radial Select Option
             |   |   |   +----------  Drive Select 4
             |   |   +--------------  Drive Select 3
             |   +------------------  Drive Select 2
             +----------------------  Drive Select 1


 Drive Select 1-2-3-4
 --------------------
 The following characteristics apply to the Drive Select lines:

  1.   Logical unit designation is established at the time of
       installation by setting the jumper plug located on the Servo
       PWA.

  2.   All control cable lines are gated with Drive Select. No data
       cable signal lines are gated with Drive Select.

  3.   Drive Select must remain active during any communication with
       the host controller.

  4.   When the radial select jumper is installed, the drive will be
       selected all the time.

  5.   The drive should not be selected until 1 second after DC power
       is applied. The Drive Ready input will be valid within 500 ns
       after the drive is selected (Drive Selected true) and after the
       35 seconds power on delay.

  6.   The drive will be selected within 1 us after the activation of
       Drive Select, if the power on sequence is complete. The drive
       will be the deselected within 1-us after the deactivation of
       Drive Select.

  7.   The drive will activate the Drive Selected signal within 1 us
       after receipt of Drive Select if the drive is selected. The
       drive will deactivate Drive Selected within 1 us after the
       Drive Select signal is deactivated.

  8.   Drive Select must be valid 100 ns minimum before the first step
       pulse is received and 100 ns minimum after the last step pulse
       is received.

  9.   At the completion of a write operation, Drive select must
       remain active for 1 us.

 10.   When the Drive Select line is activated, a ead change will
       occur, thus requiring a delay before a read or write operation
       can be initiated.


 DC Power Connector
 ------------------

          +---+---+---+---+
          | 1 | 2 | 3 | 4 |
          +--++--++--++--++
             |   |   |   +---------- + 5V
             |   |   +-------------- + 5V Return
             |   +------------------ +12V Return
             +---------------------- +12V




 Signal/Chassis Ground
 ---------------------
 The WREN 2 (RLL) Disc Drives are manufactured with the signal and
 chassis grounds common. Zero ohm resistors (designated W3 and W4) on
 the Data board allows modification of this relationship at the
 customer's option. The customer can select any of these grounding
 options by removing W3 and/or W4.

   W4         W3        Result
   -----------------------------------------------------------
 x X         X         Grounds common, quick connect terminal tied to
                       common ground

   X         O         Grounds separate, quick connect terminal tied
                       to chassis ground

   O         X         Ground separate, quick connect terminal tied to
                       signal ground

   O         O         Grounds separate, quick connect terminal float-
                       ing

 X = Connected
 O = Not Connected

 (W4/W3 are located on the upperside of the printed circuit board)

 W3 and W4 zero ohm resistors are on the Data Boards of drives which
 are Series Code Five and above. The series code of the drive is
 indicated by the first two digits of the serial number, ie, 05000001.



**********************************************************************
                      I   N   S   T   A   L   L
**********************************************************************
SEAGATE  ST4135R  PRODUCT MANUAL 77765324-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!


 Drive Orientation
 -----------------
 Only two drive mounting orientations are permitted: discs in the
 horizontal plane and discs in the vertical plane. The uppermost
 surface must be maintained in a level position or drive performance
 may be adversely affected. In the vertical plane, the drive may be
 mounted on either side, but not on either end. The drive may be not
 mounted inverted (upside down) in the horizontal orientation. It is
 recommended for optimum performance that data written in a given
 orientation be read in that same orientation.


 WREN 2 (RLL) 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 2 into an OEM's
 system, wether in a factory or field environment.


 Cooling
 -------
 Cabinet cooling must be designed by the customer so that the ambient
 temperature immediately surrounding the WREN 2 (RLL) will not exceed
 temperature limits. Specific consideration should be given to ensure
 adequate air circulation around the heat sinks on the circuit board
 on the rear of the drive.


 Interface Cabling Options
 -------------------------

 View A
    +---------------------Host-Controller---------------------+
    |                                                         |
    |Data Control   Data Control  Data Control   Data Control |
    +--+-----+--------+-----+--------+-----+--------+-----+---+
       |     |        |     |        |     |        |     |
       |     |        |     |        |     |        |     |
       |     |        |     |        |     |        |     |
       |     |        |     |        |     |        |     |
    +-++-+--++-+-+ +-++-+--++-+-+ +-++-+--++-+-+ +-++-+--++-+-+
    | |T |  |*T| | | |T |  |*T| | | |T |  |*T| | | |T |  |*T| |
    | +--+  +--+ | | +--+  +--+ | | +--+  +--+ | | +--+  +--+ |
    |    WREN    | |   WREN     | |   WREN     | |   WREN     |
    +------------+ +------------+ +------------+ +------------+

    Each control cable length must not exceed 20 feet (6.10m). Each
    data cable length must not exceed 20 feet (6.10m).


   *T  indicates removable terminator resistor pack.
    T  indicates terminator resistor pack.
    WREN data cables are permanently terminated.


 Radial Configuration
 --------------------
 View A shows each drive interfaced to its own control cable, which
 allows interfacing an arbitrary number of drives and a variety of
 system operational techniques. Each drive has its data cable and
 control cable radially connected to the host controller. The length
 of each individual cable must not exceed 20 feet (6.10 meters).
 Terminator resistors must be installed in the host controller for
 each data cable and for each control cable.



 View B
    +---------------------Host-Controller---------------------+
    |                                                         |
    |Data Control   Data          Data           Data         |
    +-+------+-------+--------------+--------------+----------+
      |      |       |              |              |
      |      |       |              |              |
      |      |       |              |              |
      |      +-------+Control+------+Control+------+Control+
    +++-+----+---+ +++-+-----+--+ +++-+-----+--+ +++-+----++-++
    ||T |        | ||T |        | ||T |        | ||T |    |*T||
    |+--+        | |+--+        | |+--+        | |+--+    +--+|
    |    WREN    | |    WREN    | |    WREN    | |    WREN    |
    +------------+ +------------+ +------------+ +------------+

    Total control cable length must not exceed 20 feet (6.10m). Each
    data cable length must not exceed 20 feet (6.10m).

   *T  indicates removable terminator resistor pack.
    T  indicates terminator resistor pack.
    WREN data cables are permanently terminated.

 Daisychain Configuration
 ------------------------
 A daisychain configuration incorporates a maximum of four drives in
 parallel on a common control cable. Only the drive selected by the
 host system has its control and data signals enabled through this
 common interface. View B shouws four WREN Disc Drives only. A
 terminator resistor pack is required in the host controller for each
 data cable. Only the last WREN 2 (RLL) in the daisychain requires a
 terminator resistor pack for the control cable. Terminator resistor
 packs for the control cable or other drives must be removed. The
 total combined control cable length (from the controller to the first
 drive, to the second and subsequent drives) must not be more than 20
 feet (6.1 meters).


 DC Cable and connector
 ----------------------
 The WREN 2 (RLL) receives DC power through a 4 pin right angle
 connector mounted on the servo circuit board. Recommended part number
 for the mating connector are provided, but equivalent parts may be
 used.

 Type of cable:      18 AWG
 Connector:          AMP 1-480424-0
 Contacts:           AMP 60619-4 (Loose Piece); AMP 61117-4 (Strip)


 Data Cable and Connector
 ------------------------
 The I/O connector for the data interface is a 20 pin board edge
 connector. The odd pins are located on the noncomponent side of the
 printed circuit board. The even pins are on the component side of the
 printed circuit board. A key slot is provided between pins 3 and 5.
 Seagate recommends keying this connector to prevent installing it
 upside down.

 Recommended part numbers for the mating connector are included below,
 but equivalent parts may be used.

 Connector:          20 pin, 3M-3461-0001, AMP 88373-6
 Cable:              Flat Cable (Stranded AWG 28) 3M-3365-20
                     Flat Cable (Stranded AWG 28) 3M-3517-20 (Shielded
                     Cable)
 Key:                AMP 583274-1, 3M-3439-0000


 Control Cable and Connector
 ---------------------------
 The I/O connector for the control interface is a 34 pin board edge
 connector. The odd pins are located on the component side of the
 printed circuit board and are connected to the ground plane. The even
 pins are on the noncomponent side of the printed circuit board. A key
 slot is provided between pin 3 and 5. Seagate recommends keying this
 connector to prevent installing it upside down.

 Recommended part numbers for the mating connector are included below,
 but equivalent parts may be used.

 Connector:          34 pin, 3M-3463-0001, AMP 88373-3
 Key:                AMP 583274-1, 3M-3439-0000
 Cable:              Flat cable (Stranded AWG 28) 3M-3365-34
                     Flat cable (Stranded AWG 28) 3M-3517-34 (Shielded
                     Cable)
                     Spectra Strip Twist'n Flat 455-248-34 (Stranded
                     AWG 28 Twisted Pair)


 Interface Drivers/Receivers
 ---------------------------
 The WREN 2 (RLL)  uses two types of signals -- single ended and
 balanced differential. The data and clock signals use balanced
 differential drivers and receivers. All other signals use single
 ended drivers and receivers.

 Single Ended Drivers/Receivers
 -------------------------------
 Transmitter Characteristics
 The WREN 2 (RLL) uses the 7438 open collector quad-2-input driver to
 transmit status to the host. This driver is capable of sinking a
 current of 48 mA with a low-level output voltage of 0.4V.

 Receiver Characteristics
 The WREN 2 (RLL) uses the 74LS14 Hex Inverter with hysteresis gate as
 a line receiver. The input of each receiver is terminated in a
 220ohm/330 ohm resistor network.

 Terminator Characteristics
 The terminator is a resistor module that plugs into a socket in the
 last drive in a daisychain. Each drive is furnished with a
 terminator. Terminators must be removed from all except the last
 drive on the cable prior to daisychain operation. An equivalent
 terminator must be provided in the controller on each input signal
 line from the drive to the controller. Only the control cable
 resistor module is removable.


 Balanced Differential Drivers/Receivers
 ---------------------------------------
 Transmitter Characteristics
 The WREN 2 (RLL) uses 26LS31 type balanced differential driver. Logic
 1 on the interface is defined when the "+" output is more positive
 than the "-" output.

 Receiver Characteristics
 ------------------------
 The WREN 2 (RLL)  uses 26LS32 type balanced differential receivers. A
 logic one on the interface is defined when the "+" input is more
 positive than the "-" input.

 Terminator Requirements
 -----------------------
 Each differential receiver in the drive is terminated with a 100 ohm
 resistor. An equivalent terminator must be provided in the controller
 on each input signal line from the drive to the controller.



**********************************************************************
                      F   E   A   T   U   R   E  S
**********************************************************************
SEAGATE  ST4135R  PRODUCT MANUAL 77765324-C

 Standards
 ---------
 The 94155-120/135 WREN 2 (RLL) has been developed as a system
 peripherals to the highest standards of design and construction. The
 WREN depends upon its 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 2 (RLL) complies with Seagate standards.

 The WREN 2 (RLL) is a UL Recognized component per UL478 and a CSA
 Certified product per CSA C22.2, No. 220-M1986. It also meets the
 requirements of DIN IEC380/VDE0806/8.81, DIN IEC 435/VDE 0805/11.84
 and EN60950/09.87.

 The WREN 2 (RLL), as delivered, is designed for system integration
 before use. It is supplied as a Class A Computing Device per the FCC
 Rules and Regulations, Part 15, Subpart J governing EMI of computing
 devices and the Radio Interference Regulations of the Canadian
 Department of Communications. However, the WREN 2 (RLL) has been
 tested and found to comply with the Class B requirements of the
 referenced FCC Rules and Regulations when installed in a typical
 commercial computing system.


 Media Description
 -----------------
 The media used in the WREN has a diameter of approximately 5
 inches (130 mm). The aluminum substrate is coated with lubricated
 ferrous oxide to permit the heads to contact the surface when start-
 ing and stopping.

 Each data surface has total of 960 tracks and is capable of record-
 ing 14,999,040 bytes of unformatted data.

 Media defects are characterized as correctable or uncorrectable de-
 pending on the type and magnitude of the media flaw. Various error
 correction codes may be implemented, but the code chosen should be
 consistent with Seagate Technology media testing and certification
 methods. In the WREN 2 (RLL) media certification is performed using
 the following standards:

            An error burst of 11 bits or less is a correctable error.

            An error burst greater than 11 bits in length is an un-
            correctable error.

 Host systems using the WREN 2 (RLL) should have, as a minimum,
 resident capabilities to recognize and map defective tracks and
 perform track reallocation routines.

 At the time of shipment from the point of manufacture, the WREN 2
 (RLL) recording surfaces will meet the following requirements.

       1. 960 total tracks per surface.

       2. Track 0 to be error free on each data surface.

       3. 30 defects per surface maximum.

       4. Cumulative defects not to exceed 1 1/2 per megabyte, based
          on total available unformatted drive capacity.

       5. Unidentified correctable errors shall not exceed two per
          surface.


 Driver/Receiver Characteristics
 -------------------------------
 Logic Level                   Drive Output         Receiver Input
 --------------------------------------------------------------------
 High (false/negated) (0)     2.5 V;   5.25 V      2.0 V;   5.25 V
 Low (true/asserted)  (1)     0.4 V;   0.0 V       0.5 V;   0.0 V

 The difference in the voltages between input and output signals is
 due to the losses in the cable.


 Seek Time
 ---------

                                          | WREN 2 |
        ----------------------------------+--------+
        Track-to-Track         msec. typ. |   5    |
                               msec. max. |   7    |
                       Average msec. typ. |  28    |
                       Average msec. max. |  32    |
        Maximum Seek Time      msec.      |  65    |
        Latency                msec. avg. |   8.34 |
        ----------------------------------+--------+

 Seek time is defined as the elapsed time from the receipt of a seek
 command by the WREN 2 (RLL) until the drive signals the controller
 that it is ready to perform another seek, or a read/write function on
 the new cylinder. Average seek time is determined by dividing the sum
 of the time for all possible movements by the total number of
 movements.


 Spindle Speed and Latency
 -------------------------
 The spindle speed is 3597   0.5% r/min. The speed tolerance includes
 motor performance and motor control circuit tolerances.

 The average latency time is 8.34 milliseconds, based on a nominal
 disc speed of 3597 r/min. The maximum latency time is 16.76 milli-
 seconds based on a maximum disc speed of 3579 r/min.


 Read Data Transfer Rate
 -----------------------
 The nominal read serial data transfer rate is 7.5 Mbits per second.


 Start/Stop Time
 ---------------
 The WREN 2 (RLL) will become ready less than 35 seconds after
 application of DC power or assertion of Motor Start I/O line. Stop
 time will be less than 30 seconds after removal of DC power.

 There is no power control switch on the WREN 2 (RLL).


 Heat/Power Dissipation
 ----------------------
 Each WREN 2 (RLL) will dissipate no more than 33.5 watts (116 BTU's
 per hour) of DC power average. Typical power dissipation under
 nominal conditions is less than 28 watts.


 Air Cleanliness
 ---------------
 The WREN 2 (RLL) is designed to operate in a typical office
 environment with minimum environmental control.

 Power Sequencing
 ----------------
 Power sequencing is not required for the WREN 2 (RLL). It protects
 against inadvertent writing during power up and down. Daisychain
 operation requires that power be maintained on the terminated unit to
 insure proper termination of the peripheral I/O cables.


 Temperature
 -----------
 50* to 113* F (10* to 45* 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 95* F (35* C)
 at 10,000 feet (3048 metres). Cabinet packaging designs must provide
 ample air circulation around the WREN 2 (RLL) 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 2 (RLL).
 The temperature of the base casting should not be allowed to exceed
 135*F (57* C) at the hottest point. The hottest point may vary
 between different applications.


 Write Precompensation
 ---------------------
 Write precompensation is recommended on all tracks, however, write
 precompensation MUSTT be performed on tracks greater than Track 128.


 Precompensation Operation
 -------------------------
 An optional 94155-120/135 configuration is available at the users
 request which requires write precompensation. This configuration must
 be specified at time of order.


 Reliability
 -----------
 The following reliability specifications assume correct host/drive
 operational interface implementation, including all interface
 timings, power supply voltages, environmental conditions, and
 appropriate data handling circuits in the host system.

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



**********************************************************************
                      G   E   N   E   R   A   L
**********************************************************************
IMPRIMIS  WREN 2 94155-120P/94155-135P PRODUCT MANUAL 77765324-C

 "P" is for marketing identification and is not shown in association
 with the model number on the drive label. Use eigth digit part number
 for identification of precompensated drives.


