ADAPTEC, INC.
=============

   ACB-4000A, ACB-4070

   +------------------------------------------------------------+
   |------------------------------------------------------------|
   | Data bus:                | None (SCSI to ST506 interface)  |
   |--------------------------+---------------------------------|
   | Size:                    | Drive card                      |
   |--------------------------+---------------------------------|
   | Hard drives supported:   | SCSI to two RLL ST506 drives    |
   |--------------------------+---------------------------------|
   | Floppy drives supported: | None                            |
   +------------------------------------------------------------+

<gopher://bitreich.org/I/th99/c/A-B/20022-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   |                   Function                   |  Location   |
   |----------------------------------------------+-------------|
   | 20-pin data cable connector-drive 0          |     CN0     |
   |----------------------------------------------+-------------|
   | 20-pin data cable connector-drive 1          |     CN1     |
   |----------------------------------------------+-------------|
   | 34-pin control cable connector-hard drive(s) |     CN2     |
   |----------------------------------------------+-------------|
   | 4-pin connector-DC power                     |     CN3     |
   |----------------------------------------------+-------------|
   | 50-pin SCSI connector-to host adapter        |     CN4     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                        SCSI ADDRESS                        |
   |------------------------------------------------------------|
   |  SCSI ID   | JP5/Jumper 1  | JP5/Jumper 2  | JP5/Jumper 3  |
   |------------+---------------+---------------+---------------|
   |    |   0   |     open      |     open      |     open      |
   |----+-------+---------------+---------------+---------------|
   |    |   1   |    closed     |     open      |     open      |
   |----+-------+---------------+---------------+---------------|
   |    |   2   |     open      |    closed     |     open      |
   |----+-------+---------------+---------------+---------------|
   |    |   3   |    closed     |    closed     |     open      |
   |----+-------+---------------+---------------+---------------|
   |    |   4   |     open      |     open      |    closed     |
   |----+-------+---------------+---------------+---------------|
   |    |   5   |    closed     |     open      |    closed     |
   |----+-------+---------------+---------------+---------------|
   |    |   6   |     open      |    closed     |    closed     |
   |----+-------+---------------+---------------+---------------|
   |>>  |   7   |    closed     |    closed     |    closed     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 USER CONFIGURABLE SETTINGS                 |
   |------------------------------------------------------------|
   |             Function             |  Location  |  Setting   |
   |----------------------------------+------------+------------|
   |>> | Write precomp. disabled      |    JP2     | pins 1 & 2 |
   |   | (ACB-4000A only)             |            |   closed   |
   |---+------------------------------+------------+------------|
   |   | Write precomp. same as       |    JP2     | pins 2 & 3 |
   |   | R.W.C. (ACB-4000A only)      |            |   closed   |
   |---+------------------------------+------------+------------|
   |   | Write precomp. to all tracks |    JP2     | pins 2 & 4 |
   |   | enabled (ACB-4000A only)     |            |   closed   |
   |---+------------------------------+------------+------------|
   |>> | DMA transfer rate is         | JP5/jumper |   closed   |
   |   | SYSCLOCK/4                   |     4      |            |
   |---+------------------------------+------------+------------|
   |   | DMA transfer rate is         | JP5/jumper |    open    |
   |   | DATACLOCK/2                  |     4      |            |
   |---+------------------------------+------------+------------|
   |>> | Extended command set enable  | JP5/jumper |   closed   |
   |   | - SASI compatible            |     5      |            |
   |---+------------------------------+------------+------------|
   |   | Extended command set         | JP5/jumper |    open    |
   |   | disabled                     |     5      |            |
   |---+------------------------------+------------+------------|
   |>> | Not used                     | JP5/jumper |    open    |
   |   |                              |     6      |            |
   |---+------------------------------+------------+------------|
   |>> | Supports the SEEK COMPLETE   | JP5/jumper |   closed   |
   |   | line during head switches    |     7      |            |
   |---+------------------------------+------------+------------|
   |   | SEEK COMPLETE Cmd. not       | JP5/jumper |    open    |
   |   | supported                    |     7      |            |
   |---+------------------------------+------------+------------|
   |>> | Self-diagnostics enabled     | JP5/jumper |   closed   |
   |   |                              |     8      |            |
   |---+------------------------------+------------+------------|
   |   | Normal operation             | JP5/jumper |    open    |
   |   |                              |     8      |            |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |               MISCELLANEOUS TECHNICAL NOTES                |
   |------------------------------------------------------------|
   |  The function of JP1 is to determine the select technique  |
   |            used to interface the host adapter.             |
   |                                                            |
   |  Soldering Pin 2 to Pin "P" allows for the "pulse" select  |
   |   that is used by controllers designed to work with SASI   |
   |  hosts. Soldering Pin 2 to Pin "H" or "L" allows for the   |
   |     "level" select signal used in accordance with SCSI     |
   |                         standards.                         |
   +------------------------------------------------------------+