M 8 4 5 0    MINISCRIBE

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                                                      Native|  Translation
Form                 3.5"/HH               Cylinders     771|     |     |
Capacity form/unform    41/   48 MB        Heads           4|     |     |
Seek time   / track  45.0/12.0 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 2/7                        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          10.7 W     Shock        g        10       |     70
       seek               W     Rotation   RPM      3600
       read/write         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

  |                                                         |XX
  |                                                  +-SEL1 |XX
  |                                                  | |    |XX P2
  |                                                  | |    |XX
  |                                              +J15+-+    |XX
  |                                              ++         |
  |                                            +J13         |XX
 ++ LED                                        ++           |XX
 ++                                                   ++    |XX P1
  |                                                RP1||    |XX
  |                                         Terminator||    |XX
  |                                                   ||    |XX
  |           ++                                      ++    |XX
  |           |J12                                          |XX
  |           ++                                            |XX
  |                                                         |
                                              Power  xxxxxx


                      J   U   M   P   E   R   S

 Jumper Setting

 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 of
 the SEL 1 header must be repositioned to one of the other three rows
 corresponding to the desired drive select number. Row 1, correspond-
 ing with Drive Select 1, is the topmost row when the interconnected
 column of pins is on the right.

 SEL 1

   +---+           +---+          +---+            +---+
 1 |xxx|          1|O O|         1|O O|           1|O O|
 2 |O O|          2|xxx|         2|O O|           2|O O|
 3 |O O|          3|O O|         3|xxx|           3|O O|
 4 |O O|          4|O O|         4|O O|           4|xxx|
   +---+           +---+          +---+            +---+
  Drive 1         Drive 2        Drive 3          Drive 4

 As shipped by MiniScribe with Drive Select 1 selected.

 Drive Exercise/Head Park Option
 When power is first applied, the drive performs power-on diagnostics.
 After the diagnostics, the status of jumper 13 is checked. It is
 open, the normal drive ready mode is entered. If jumper 13 is
 closed (jumpered), the drive enters the exercise mode where crescendo
 seeks are performed continually until power is removed. Any seek or
 spin failure occurring during this mode causes the drive diagnostic
 LED to flash a code indicating the type of failure.

 To park the heads, remove power and place a jumper in J13. Apply
 power. The heads will rezero (go to cylinder 0) and then to the
 shipping zone at cylinder 810 when power is removed. Remove the
 jumper immediately.

 Low Power/Head Park Option
 The jumper in J15 removed enables the low power option. With this
 option, whenever the drive has not been selected for 30 seconds the
 head assembly is automatically moved to the shipping cylinder (810)
 and current is removed from the stepper motor. In this mode the drive
 power consumption is reduced to 7 watts. Should power be removed
 from the drive at this point, the heads will land in the shipping
 zone. If power is not removed, the heads will remain over the
 shipping cylinder until told to go to the cylinder indicated by the
 next Read or Write command.

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

 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 13 to determine
 its state (open or closed). Briefly, Jumper 13 (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 13. If open, go to normal operation. If closed,
    continue to Step 4.

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

 5. Test Jumper 13. 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

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


                      I   N   S   T   A   L   L

 Notes on Installation

 Recommended Mounting Configuration
 The MiniScribe 8450 3 1/2 inch size drive is designed to be used in
 applications where the unit may experience shock and vibrations at
 greater levels than larger and heavier disk drives.

 Two features which allow greater shock tolerances are the use of
 rugged media and shock mounts. To take full advantage of the shock
 mounts, however, it is necessary to provide a 0.1 inch clearance on
 both the top and bottom of the drive. This clearance allows for move-
 ment of the drive during acceleration.

 The drive may be mounted in any attitude.

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

 Mechanically Isolated Mounting Points
 Four side mounting and four base mounting points are provided to the
 customer. Each mounting point is mechanically isolated from the head-
 disk assembly.

 Connect interface cables with connectors P1, P2, and P3 to J1,
 J2, and J3 respetively. Insure that connectors P1 and P2 have
 keys installed. If multiple drives are be interconnected, remove the
 terminator packs in all but the last drive in the daisy chain.

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

 Drive Mechanism
 A brushless DC direct drive motor rotates the spindle at 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 life a clean, above
 atmospheric pressure environment to the heads and disks.

 Head Positioning Mechanism
 Four read/write heads on the drive are supported by a carriage
 mechaism coupled to the stepper motor through a rack-and-pinion
 motion translator.

 Read/Write Heads and Disks
 Data is recorded on two (2) 95 mm diameter disk through four (4)
 Mini-Winchester type composite heads.

 Power Sequencing
 +5 volts DC and +12 volts DC may be applied in any order.

 +12 VDC powers the spindle drive motor. The microprocessor verifies
 that the disks are spinning at 3600 rpm and then activates the
 automatic Track Zero positioning. -TRACK ZERO, -SEEK COMPLETE, and
 -READY will beome true upon completion of the Track Zero positioning

 Electrical Interface
 The interface to the MiniScribe 8450 can be divided into three
 categories, each of which are physically separated: Comtrol Signals,
 Data Signals and DC Power.

 All Control Signals are digital in nature (open collector TTL) and
 either provide signals to the drive (input) or signals to the
 controller (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

 The voltage return lines of P3 should only be grounded at the power

 Cable Interconnection - 4 Drive System

   +-----------+                                +-----------------+
   |           +---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

 P1 Connector - Control Signals
 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 componet side
 of the printed circuit board. A key slot is provided betweeen pins 4
 and 6.

 The recommended mating connector (J1) is AMP Ribbon Connector, P/N

 P2 Connector - Data Signals
 Connection to P2 is through a 20 pin edge connector. The pins are
 numbered 1 through 20 with the odd pins located on the component 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

 P3 Connector - DC Power
 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.

      +-----P3-----+   pin 1    +12 VDC
      | 4  3  2  1 |   pin 2    +12 Ground Return
      +------------+   pin 3    + 5 Ground Return
                       pin 4    + 5 VDC

 The Miniscribe drive is a precision product weighing 1.8 pounds.
 During handling the unit must not be dropped, jarred or bumped.
 Otherwise, damage to the heads and disks may occur. When the drive is
 removed from the Miniscribe shipping container and not immediately
 secured within a chassis through its shock mounts, it must be stored
 on a soft padded surface.

 Failure to comply with the above procedure will render null and void
 all warranties.

 When removing the PCBA, a grounded wirst strap must be worn to
 prevent esd damage.


                      F   E   A   T   U   R   E  S

 The MiniScribe 8450 is a half-height reandom access 95 mm rigid
 media disk drive employing Winchester technology. The drive utilizes
 a rack-and-pinion actuator, microprocessor control, and open loop
 stepper head positioning.

 The Model 8450 features power up diagnostics, buffered seek and 7.5
 Megabit/Sec. 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)
       |                                  | 8450   |
       |Track-to-Track         msec. typ. |  12    |
       |Average                msec. typ. |  45    |
       |                       msec. max. |  96    |
       |Latency                msec. avg. |   8.33 |

 Media Defect Criteria (as shipped from MiniScribe)
 Model 8450   10 defects surface/maximum
              20 defects maximum
              2 bytes or less in length
              Cylinder Zero and One Defect Free

 Error Messages
 The microprocessor performs wake up diagnostics on power up.
 Additionally, some operations are monitored during normal operations.
 If an error is detected, the microprocessor will flash a warning by
 blinking the activity LED.

 Error codes may be generated by the microprocessor to indicate hard-
 ware failures or warnings that are detected during power-on
 diagnostics, burn-in mode, or normal operation. Error codes are
 diaplayed in a "morse-code" type manner. Bits may be interpreted and
 converted into hexadecimal error codes. "Zeros" are indicated by
 a short (1/2 second) flashingn mode. "Ones" are indicated by a short
 (1/2 second) continuous ON mode. Error "Words" are separated by a one
 second LED off time.

    Zero                  = 0.5 second flashing mode
    One                   = 0.5 second continuous ON mode
    Between Bits          = 0.5 second Off
    Between Repeat Cycles = 1.0 second Off

 Listed Below are the binary to hexadecimal conversion values:

  0 = 0000   4 = 0100   8 = 1000   C = 1100
  1 = 0001   5 = 0101   9 = 1001   D = 1101
  2 = 0010   6 = 0110   A = 1010   E = 1110
  3 = 0011   7 = 0111   B = 1011   F = 1111

 Message Definitions
 Code 0 - Microprocessor RAM error
 Code 1 - Microprocessor ROM checksum error
 Code 2 - Interface chip diagnostic failure
 Code 3 - Write Fault latch will not reset
 Code 4 - Index pulse not detected during spinup
 Code 5 - Unable to reach 3600 rpm in 30 seconds
 Code 6 - Unable to stabilize spin speed in 10 seconds
 Code 7 - Unable to maintain spin speed to 0.5%
 Code 8 - Unable to uncover Track Zero sensor
 Code 9 - Unable to cover Track Zero sensor
 Code A - Track Zero interrupter misadjusted
 Code B - Shipping zone error, crash stop misadjusted
 Code C - Carriage stuck during recal error
 Code D - Seek errror during burn-in or recal
 Code E - No hall transitions during spin-up
 Code F - Unexpected interrupt from processor

 Write Data
 In recording, to optimize data integrity and meet the error rate
 specified, the write data presented by the controller must be pre-
 compensated from Track 128 to Track 770.

 Track Accessing
 A seek to cylinder 810 will position the read/write heads over the
 shipping zone.

 A seek to a higher cylinder than 810 will cause a recalibration
 sequence in the drive, which will position the read/write heads at
 Track Zero.