40 MB Internal Hard Drive  (250-4061)  Settings        Faxback Doc. # 4975

* The 40 MB Hard Disk Drive is a half-height Winchester fixed-disk drive.

* The 40 MB Hard Disk Drive interface is compatible with the Seagate
  ST506/ST412 standard interface.

* The 40 MB Hard Disk Drive features an automatic shipping lock that
  disengages when the drive is powered on.

* Can operate at temperatures from 50 to 122`F with 8 to 80% non-condensing
  humidity.

* The standard Drive Select setting set at the factory configures the 40 MB
  Hard Disk Drive as the first (primary) disk drive.  The standard
  Terminator setting configures the Hard Disk Drive as the terminal disk
  drive.

* Possible pin/switch settings for the 40 MB Hard Disk Drive are shown in
  the following chart.

──────────────────────────────────────┬────────────────────────────────────
CONTROL DATA                          │MICROSCIENCE
MODEL 94205-51                        │MODEL HH 1050
──────────────────────────────────────┼────────────────────────────────────
Starting from the left, the first four│Switches 1-4 are for drive selection
pairs of pins are for drive selection.│Set one of these switches in the ON
Jumper one of these sets to configure │position to configure the hard disk
the hard disk as Drive 1,2,3, or 4 (C,│as Drive 1,2,3,or 4 (C,D,E, or F),
D,E, or F), respectively.             │respectively.
                                      │
NOTE: The third and fourth sets       │NOTE: Switches 3 and 4 provide
of pins provide hardware              │hardware support for a third and
support for a third and fourth        │fourth hard disk. The Hard Disk
hard disk. The Hard Disk              │Controller board (25-4060) for your
Controller board (25-4060)            │computer does not support more than
for your computer does not            │two hard disk drives.
support more than two hard            │
disk drives.                          │Switches 5-9 are for drive
                                      │termination. Set all these switches
The last three pairs of pins are not  │in the ON position to configure the
used.                                 │hard disk drive as the terminal
                                      │drive. Otherwise, set ALL these
This drive includes a resistor for    │switches in the OFF position.
drive termination. Be sure the        │
resistor is installed to configure the│Switch 10 is not used.
hard disk as the terminal drive.      │
Otherwise, remove the resistor with   │
tweezers or needle-nosed pliers.      │
                                      │
NOTE: Re-installing the terminator    │
resistor requires partial disassembly │
of the hard disk drive. Never attempt │
to disassemble the hard disk drive.   │
Servicing the hard disk drive requires│
special facilities. Take the drive to │
an authorized Radio Shack Service     │
Center for servicing.                 │
──────────────────────────────────────┴────────────────────────────────────

    Drive Select / Termination Information:

    CDC: 94205-51

  \ \\<----->Terminator Resister is located on the
   \ \\ |    right rear side of the Hard Drive
    \ \||                                                        |
     \  |                                                        |
      \ |                                                        |
       \|          1 ____                1 _ _ _ _ _ _ _         |
        |_______||__|    |____________||__| : : : : : : |________|
           20 Pin              34 Pin      Drive Select    Power
         Connector            Connector      Jumpers

                        Drive Select Jumper Options
                            o  o  o  o  o  o  o
                            o  o  o  o  o  o  o
                            |  |  |  |  |  |  |
         Drive Select 1_____|  |  |  |  |  |  |_____Reserved
         Drive Select 2________|  |  |  |  |________Reserved
         Drive Select 3___________|  |  |___________Radial Select 
         Drive Select 4______________|              Option

    Rodime: /A 3055

          |                 o o o o                   |
          |                 o o o o                   |
          |   =========     | |_____Drive Select 2    |
          |   ^             |_______Drive Select 1    |
          |   |__Terminator     ________            __|
          |____________________|        |__________|

    Microscience HH-1050

    |                    _____________                        |
    |                   |_____________| SW 1                  |
    |                                                         |
    |_____          ___                _________           ___|
          |   J2   |   |      J1      |         |    P3   |
          |________|   |______________|         |_________|

                     ___________________SW PINS (1-4)
                  __|__
                 /_____\ ____________
                |1 2 3 4 5 6 7 8 9 10|
                |____________________|  SW1
                         \_________/
                              |_________SW PINS (5-10) Termination

        SW1(1-4)   1    2    3    4         SW1(5-10)
  Drive Select 1   ON   OFF  OFF  OFF     Termination     All ON
  Drive Select 2   OFF  ON   OFF  OFF     No Termination  All OFF
  Drive Select 3   OFF  OFF  ON   OFF
  Drive Select 4   OFF  OFF  OFF  ON

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