M 8 4 2 5    MINISCRIBE

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                                                      Native|  Translation
                                                      ------+-----+-----+-----
Form                 3.5"/HH               Cylinders     615|     |     |
Capacity form/unform    21/   26 MB        Heads           4|     |     |
Seek time   / track  68.0/15.0 ms          Sector/track   17|     |     |
Controller           MFM / ST506           Precompensation 65535
Cache/Buffer               KB              Landing Zone      614
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         4 50    |    -40 60
Power: sleep              W     Humidity     %         8 80    |      5 95
       standby            W     Altitude    km    -0.061  3.048|        12.192
       idle               W     Shock        g        10       |     70
       seek          10.0 W     Rotation   RPM      3600
       read/write    11.2 W     Acoustic   dBA        45
       spin-up            W     ECC        Bit
                                MTBF         h      20000
                                Warranty Month
Lift/Lock/Park     YES          Certificates     FCC                          

**********************************************************************
                        L   A   Y   O   U   T
**********************************************************************
MINISC.  8212/8412/8425/8438  PRODUCT MANUAL P/N 1010 REV. T

  Universal I PCBA
  +---------------------------------------------------------+
  |                                                   SEL   |XX
  |                                         J19++     +-+   |XX
  |                                            ++     | |   |XX P2
  |                                   J18+--+         | |   |XX
  |                                      +--+   +-+   +-+   |XX
  |                                          J13| |         |
  |                                             +-+   ++    |XX
  |+--J16                                             ||    |XX P1
  |+--+                                            RP1||    |XX
  |                        J15---+          Terminator||    |XX
  |                 J17+-+   +---+                    ++    |XX
  |                    +-+                                  |XX
  |                                                         |XX
  |                                                         |XX
  |                                                         |
  +--------------------------------------------------xxxxxx-+
                                              Power  xxxxxx
 Earlier versions of PCBA do not contain J13, J15, J17, J18, J19, and
 the LED is soldered directly into PCBA.




  Universal II PCBA
  +---------------------------------------------------------+
  |                                                   SEL   |XX
  |                                         J19++     +-+   |XX
  |                                            ++     | |   |XX P2
  |                                   J18+--+         | |   |XX
  |                                      +--+   +-+   +-+   |XX
  |                                          J13| |         |
  |                                             +-+   ++    |XX
  |                                                   ||    |XX P1
  |                                                RP1||    |XX
  |                                         Terminator||    |XX
  |                 J17+-+                            ++    |XX
  |                    +-+                                  |XX
  |                                                         |XX
  |                                                         |XX
  |                                                         |
  +--------------------------------------------------xxxxxx-+
                                              Power  xxxxxx



**********************************************************************
                      J   U   M   P   E   R   S
**********************************************************************
MINISC.  8212/8412/8425/8438  PRODUCT MANUAL P/N 1010 REV. T

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

 x = Jumpers set at factory


 Customer options are limited to the drive select address (SEL) and
 burn-in mode on drives dhipped to mid-1986. On newer drives there are
 additional options which may be selected. On all drives normal opera-
 tion is achieved no jumper or trace modifications.


 SEL  Drive Select
 -----------------
 As shipped, the drive is preselected for drive select address 1. To
 change to another address, the two position jumper located in row 1
 of the SEL 1 header must be repositioned to one of the other three
 rows corresponding to the desired drive select number.( Row 1,
 corresponding with Drive Select 1, is the topmost row when the inter-
 connected column of pins is on the right.)
                   +----+
  x              1 |xxxx| Drive select 1.
                 2 |O  O|
                 3 |O  O|
                 4 |O  O|
                *5 |O  O|
                   +----+
 * Universal II PCBA does not contain position 5.


 Universal PCBA Jumper Functions
 -------------------------------
 On PCBA's with P/N 30085120X, the following jumpers are available:


  J13B  Low power option 1
  ------------------------
        OPEN   Current from stepper motor is removed after no activity
               for 30 seconds.

  J13C  Low power option 2
  ------------------------
        OPEN   Seek to ship zone is performed before stepper power is
               removed. Note that J13B has to be open also.

  J15  Seek complete
  ------------------
       OPEN    Delays seek complete by 3 milliseconds.

  J17  Daisy-Chained
  ------------------
       CLOSED  Allows data cable to be daisy-chained.

  J18  LED
  --------
       Normally 1 and 2 are jumpered. If 2 and 3 are jumpered, this
       connects the LED drive select.

  J19  UNSAFE/MOTOR ON
  --------------------
       CLOSED   Asserts -UNSAFE through +MOTOR ON.

  J21  Voltage
  ------------
       Normally 2 and 3 are jumpered. If 1 and 2 are jumpered, a
       voltage fault will occur at a higher voltage.



 The following table depicts how drives with Universal I PCBA and the
 Universal II PCBA are shipped from the factory.

                           UNIVERSAL I

 Module  J13A   J13B   J13C   J15    J17    J18 1-2  J18 2-3  J19
 ---------------------------------------------------------------------
 07      OPEN   CLOSE  CLOSE  CLOSE  CLOSE  CLOSE    OPEN     OPEN
 08      OPEN   CLOSE  CLOSE  CLOSE  CLOSE  CLOSE    OPEN     OPEN


                           UNIVERSAL II

 Module  J13A   J13B   J13C    J17    J19   J21 2-3  J21 1-2
 ------------------------------------------------------------
 05      OPEN   CLOSE  CLOSE  CLOSE  OPEN   CLOSE    OPEN
 22      OPEN   CLOSE  CLOSE  CLOSE  OPEN   CLOSE    OPEN
 23      OPEN   CLOSE  CLOSE  CLOSE  OPEN   OPEN     CLOSE
 24      OPEN   CLOSE  CLOSE  CLOSE  CLOSE  CLOSE    OPEN


 Diagnostic and Exercise Routines
 --------------------------------
 The microprocessor performs wake up diagnostics upon application of
 power. If an error is detected, the processor will flash a warning by
 blinking the activity LED. Some errors are fatal in that they do not
 return to the program until power is cycled.

 If no errors are detected, the processor tests Jumper A to determine
 its state (open or closed). Briefly, Jumper A (Drive Exercise
 Options) is as follows:

 The jumper is left open for normal (online) operations. If the
 jumper is closed, (and left closed) a burn-in (cresendo seeks)
 program will be run. If the jumper is closed and opened during the
 code level display, the sensor adjust routine is initiated.

 Power-up sequence of events is as follows:

 1. Apply power

 2. The microprocessor runs power on diagnostics and then allows motor
    spin up.

 3. Test Jumper A. If open, go to normal operation. If closed,
    continue to Step 4.

 4. Display code level (5 bits), e.g. 00001

 5. Test Jumper A level. If still closed, continue in cresendo seek
    exerciser mode. If open, run Track Zero sensor adjust.

 6. Recalibrate access, then seek to maximum cylinder.

 7. The LED will display seven zero's (flash code). At this time the
    heads are located over the shipping zone. If power is removed, the
    heads will land in the shipping zone.

 8. If the test is continued the drive will perform a seek to
    cylinder four, (test for seek error) and then seek to cylinder
    zero.

 9. At this point the sequential seek burn-in will begin.



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                      I   N   S   T   A   L   L
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MINISC.  8212/8412/8425/8438  PRODUCT MANUAL P/N 1010 REV. T

 Notes of installation
 =====================

 Installation direction
 ----------------------

     horizontally                           vertically
   +-----------------+             +--+                       +--+
   |                 |             |  +-----+           +-----+  |
   |                 |             |  |     |           |     |  |
 +-+-----------------+-+           |  |     |           |     |  |
 +---------------------+           |  |     |           |     |  |
                                   |  |     |           |     |  |
                                   |  |     |           |     |  |
 +---------------------+           |  +-----+           +-----+  |
 +-+-----------------+-+           +--+                       +--+
   |                 |
   |                 |
   +-----------------+

 Drive Orientation
 -----------------
 The drive may be mounted in any attitude.


 Mounting Configuration
 ----------------------
 The Miniscribe 8212, 8412, 8425 and 8438 quarter size drives are
 designed to be used in applications where the unit may experience
 shock and vibration at greater levels than larger and heavier disk
 drives.

 Two features which allow greater shock tolerance are the rugged media
 and shock mounts. To take full advantage of the shock mounts,
 however, it is necessary to provide a minimum of 0.1 inch clearence
 on both the top and sides of the drive. This clearence allows for
 movement of the drive during acceleration.

 The drive is mounted using 6-32 screws, 1/8 inch maximum penetration.
 The customer should allow adequate ventilation for the drive to en-
 sure reliable drive operation over the operating temperature range.


 Mechanically isolated mounting points
 -------------------------------------
 Four (4) side mounting and four (4) base mounting points are
 provided to the customer. Each mounting point is mechanically isola-
 ted from the head-disk assembly.


 Cabling
 -------
 Connect interface cables with connector P1, P2 and P3 to J1, J2 and
 J3 respectively. Iff multiple drives are to be interconnected, remove
 the terminator packs in all but the last drive of the daisy chain.


 Cable Interconnection - 4 Drive System
 --------------------------------------

       HOST
   +-----------+                                +-----------------+
   |           +---o---Control------------------+P1     Drive 1   |
   |           |   |    +-------Data------------+P2               |
   |           |   |    |             +-Power---+P3        ...    |
   |           |   |    |             |         +-----------------+
   |           |   |    |             |         +-----------------+
   |Controller |   o----+-------------+---------+P1     Drive 2   |
   |           |   |    | +-----------+---------+P2               |
   |           |   |    | |           o---------+P3        ...    |
   |           |   |    | |           |         +-----------------+
   |           |   |    | |           |         +-----------------+
   +-----------+   o----+-+-----------+---------+P1     Drive 3   |
   |           |   |    | | +---------+---------+P2               |
   |           +---+----+ | |         o---------+P3        ...    |
   |           +---+------+ |         |         +-----------------+
   |Data       +---+--------+         |         +-----------------+
   |Separator  |   +------------------+---------+P1     Drive 4   |
   |           +----------------------+---------+P2               |
   |           |                      o---------+P3        XXX    |
   +-----------+                      |         +-----------------+
                       DC voltages----+

 ... = Terminator Pack removed

 XXX = Terminator Pack installed


 Terminators
 -----------
 Each drive is shipped with a terminator pack providing the 220/330
 ohn termination for the Control Input Signals. If multiple drives are
 configured in a daisy chain configuration, the terminator pack must
 be removed from all except the last unit on the daisy chain.


 P1 Control Signal Connector
 ---------------------------
 Connection to P1 is through a 34 pin PCB edge connector. The pins are
 numbered 1 through 34 with the odd pins located on the circuit side
 of the Printed Circuit Board. A key slot is provided between pins 4
 and 6.

 The recommended mating connector (J1) is AMP Ribbon Connector, P/N
 88373-3.


 P2 Data Signals Connector
 -------------------------
 Connection to P2 is through a 20 pin edge connector. The pins are
 numbered 1 through 20 with the odd pins located on the circuit side
 of the Printed Circuit Board. A key slot is provided between pins 4
 and 6.

 The recommended mating connector (J2) is AMP Ribbon Connector,
 P/N 88373-6.


 P3 DC Power Connector
 ---------------------
 DC power connector (P3) is a 4 pin AMP Mate-N-Lok Connector, mounted
 on the PCB.

 The recommended mating connector (J3) is AMP P/N 1-480424-0 utilizing
 AMP pins P/N 350078-4.

       +------------+    1 = +12 Volts DC
       | 4  3  2  1 |    2 = +12 Volts Ground Return
       +------------+    3 = + 5 Volts Ground Return
                         4 = + 5 Volts DC


 Electrical Interface
 --------------------
 The interface to the MiniScribe 8212, 8412, 8425 and 8438 can be
 divided into three categories, each of which is physically separated:
 Control Signals, Data Signals and DC Power.

 All control Signals are digital in nature (open collector TTL), and
 provide signals either to the drive (input) or signals to the
 collector (output). The Data Signals are differential in nature and
 provide data either to (write) or from (read) the drive.

 The interconnect cable between the drive and controller may be flat
 ribbon or twisted pairs of a length not to exceed 20 feet. The signal
 return lines and ground lines for P1 and P2 should be grounded at the
 controller.



**********************************************************************
                      F   E   A   T   U   R   E  S
**********************************************************************
MINISC.  8212/8412/8425/8438  PRODUCT MANUAL P/N 1010, REV. T

 Introduction
 ------------
 The Miniscribe 8212, 8412, 8425 and 8438 are half-height random
 access 95 mm rigid media disk drives employing Winchester technology.
 The drives utilize a rack-and-pinion actuator, microprocessor
 control, and open stepper head positioning.

 The drives feature power up diagnostics and buffered seek. Models
 8212, 8412 and 8425 have a data transfer rate of 5 Megabit/Sec, while
 the 8438 features a 7.5 Megabit/Sec data transfer rate. D.C. voltages
 and physical form factor are the same as the 3-1/2 inch half height
 floppy disk drive.


 Seek time
 ---------
 (Including settling time)   |   8438    |          |
                             | 8212,8425 | 8412     |
 ----------------------------+-----------+----------+
 Average Single Track *      |  15 ms    |  15 ms   |
 Average                     |  68 ms    |  50 ms   |
 Maximum                     | 152 ms    | 120 ms   |
 Average Latency             |   8.33 ms |   8.33 ms|
 ----------------------------+-----------+----------+

 * Worst Case Single Track Seek: 15.4 ms.


 Reliability and Maintenance
 ---------------------------
 MTBF                     20,000 hours (continuous operation) at 35*C
 MTTR                     30 minutes
 Preventive Maintenance   None
 Component Design Life    5 years



 Media Defect Criteria
 ---------------------

 Models 8212 & 8412          Models 8425 & 8438
 --------------------        ---------------------
 6 defects/surface maximum   6 defects/surface maximum
 10 defects maximum          20 defects maximum
 2 bytes or less in length   2 bytes or less in length
 Cylinder Zero Defect Free   Cylinder Zero and one Defect Free


 Magnetic Field
 --------------
 The externally induced magnetic flux density may not exceed 3 Gauss
 as meaured at the disk surface.


 Drive Mechanism
 ---------------
 A brushless DC direct drive motor rotates the spindle a 3600 rpm.
 The motor/spindle assembly is dynamically balanced to provide minimal
 mechanical runout to the disks. A dynamic brake is used to provide a
 fast stop to the spindle motor when power is removed.


 Air Filtration System
 ---------------------
 Within the sealed enclosure, a 0.3 micron filter coupled with a
 breather filter, provides over the drive live, a clean, above
 atmospheric pressure environment for the heads and disks.


 Head Positioning Mechanism
 --------------------------
 Two (2) read/write heads on the Model 8212 and four (4) read/write
 heads on the Models 8412, 8425 and 8438 are supported by a carriage
 mechanism coupled to the stepper motor through a rack-and-pinion
 motion translator.


 Track Zero Detector
 -------------------
 The Track Zero Detector resides on the stepper motor. This optical
 sensor consists of a light source (activated only ehen a seek is
 initiated) and a receiver which when blocked by an interrupter on the
 motor shaft, indicates one of several logical Track Zero positions.
 The microprocessor determines the physical location of Track Zero
 from the redundant logical Track Zeros.