Drives

                                    Drives

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* Pin-outs for ST3144A 120M IDE hard disk (included with stock A4000):

                           Seagate ST3144A Jumpers

                 |       1  3  5  7  9
                 |      ---------------
                 |     | o  o  o  o  o |
                 |     |               |   Front Of Drive -->
                 |     | o  o  o  o  o |
                 |      ---------------
                 |       2  4  6  8  10
                 |
                  -------------------------------------------------------

   Single drive:     Pins 3-4 jumpered.
   Two-drive master: Pins 3-4 jumpered and pins 5-6 jumpered.
   Two-drive slave:  Pins 3-4 open and pins 5-6 open.
   LED connected:    Pins 9-10 must be jumpered to connect to an activity LED
                     on the controller. Without this jumper, the drive will
                     work, but there will be no activity light (unless you
                     connect an LED to the connector on the front of the
                     drive itself).

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* Pin connections for external SCSI-2 half-pitch connector:

  NOTE: Connector is VIEWED     |\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/|
  FROM THE BACK, or inside      |  1                       49  |
  of the computer.  All odd-    |  --------------------------  |
  numbered wires go to the      |  \\                        /  |
  top of the connector, and     |   ------------------------   |
  all even-numbered wires go    |  2                       50  |
  to the bottom.                |/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\/\\|

  Procedure: split the 50-pin SCSI ribbon cable connectors back a couple of
  inches. Start with pin 1, lay it in the crimp-on pins at the upper left of
  the connector (again, viewed from the back of the connector). By placing
  the two sides of a small pair of needle-nose pliers on the wire on either
  side of the crimp pins, you can gently force the wire down into the V-
  shaped gap between them. Locate wire #2, then use the same procedure to
  connect it to the other side of the connector. Repeat for all 50 wires,
  then clip the plastic retaining clips onto the connector and give it a
  final squeeze to make sure all wires are making contact.

  You can cut a hole in the A4000's "Expansion" port cover on the back of the
  machine to hold this new connector (a "nibbling" tool works well for this).

  Don't forget proper SCSI termination: the devices at both ends of the chain
  should be terminated. If the internal SCSI device on the bus before this
  connector is not terminated--and it shouldn't be if you want this connector
  to be functional--external devices plugged into this port should be
  terminated.  You could also plug a half-pitch terminator directly into this
  new external port.

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