ABIT COMPUTER CORPORATION
=========================

   AS420/AS425/AS433/AS455

   Processor          80486SX/80486DX                             
   Processor Speed    20/25/33/40MHz                              
   Chip Set           SIS                                         
   Max. Onboard DRAM  32MB                                        
   Cache              32/64/128/256/512/1024KB                    
   BIOS               AMI                                         
   Dimensions         330mm x 214mm                               
   I/O Options        None                                        
   NPU Options        4167                                        

<gopher://bitreich.org/I/th99/m/S-T/35052-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   | Purpose          | Location | Purpose           | Location |
   |------------------+----------+-------------------+----------|
   | Turbo LED        |    D6    | Reset             |   JP20   |
   |------------------+----------+-------------------+----------|
   | External battery |   JP15   | Speaker           |   JP21   |
   |------------------+----------+-------------------+----------|
   | Turbo switch     |   JP19   | Power LED &       |   JP22   |
   |                  |          | keylock           |          |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 USER CONFIGURABLE SETTINGS                 |
   |------------------------------------------------------------|
   |               Function               | Jumper |  Position  |
   |--------------------------------------+--------+------------|
   |>> | Factory configured - do not      |  JP2   |    Open    |
   |   | alter                            |        |            |
   |---+----------------------------------+--------+------------|
   |>> | Monitor type select monochrome   |  JP4   |    Open    |
   |---+----------------------------------+--------+------------|
   |   | Monitor type select color        |  JP4   |   Closed   |
   |---+----------------------------------+--------+------------|
   |>> | CMOS memory normal operation     |  JP5   | pins 1 & 2 |
   |   |                                  |        |   closed   |
   |---+----------------------------------+--------+------------|
   |   | CMOS memory clear                |  JP5   | pins 2 & 3 |
   |   |                                  |        |   closed   |
   |---+----------------------------------+--------+------------|
   |>> | Factory configured - do not      |  JP6   | pins 1 & 2 |
   |   | alter                            |        |   closed   |
   |---+----------------------------------+--------+------------|
   |>> | Factory configured - do not      |  JP8   | pins 1 & 2 |
   |   | alter                            |        |   closed   |
   |---+----------------------------------+--------+------------|
   |>> | Factory configured - do not      |  JP14  | pins 1 & 2 |
   |   | alter                            |        |   closed   |
   |---+----------------------------------+--------+------------|
   |>> | Factory configured - do not      |  JP17  | pins 1 & 2 |
   |   | alter                            |        |   closed   |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     DRAM CONFIGURATION                     |
   |------------------------------------------------------------|
   |       Size       |       Bank 0       |       Bank 1       |
   |------------------+--------------------+--------------------|
   |       1MB        |    (4) 256K x 9    |        NONE        |
   |------------------+--------------------+--------------------|
   |       2MB        |    (4) 256K x 9    |    (4) 256K x 9    |
   |------------------+--------------------+--------------------|
   |       4MB        |     (4) 1M x 9     |        NONE        |
   |------------------+--------------------+--------------------|
   |       8MB        |     (4) 1M x 9     |     (4) 1M x 9     |
   |------------------+--------------------+--------------------|
   |       16MB       |     (4) 4M x 9     |        NONE        |
   |------------------+--------------------+--------------------|
   |       32MB       |     (4) 4M x 9     |     (4) 4M x 9     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                    CACHE CONFIGURATION                     |
   |------------------------------------------------------------|
   |  Size  |   Bank 0   |   Bank 1   | TAG (U28 & | TAG (U30)  |
   |        |            |            |    U29)    |            |
   |--------+------------+------------+------------+------------|
   |  32KB  | (4) 8K x 8 |    NONE    | (2) 16K x  |    NONE    |
   |        |            |            |     4      |            |
   |--------+------------+------------+------------+------------|
   |  32KB  | (4) 8K x 8 |    NONE    |    NONE    | (1) 8K x 8 |
   |--------+------------+------------+------------+------------|
   |  64KB  | (4) 8K x 8 | (4) 8K x 8 | (2) 16K x  |    NONE    |
   |        |            |            |     4      |            |
   |--------+------------+------------+------------+------------|
   |  64KB  | (4) 8K x 8 | (4) 8K x 8 |    NONE    | (1) 8K x 8 |
   |--------+------------+------------+------------+------------|
   | 128KB  | (4) 32K x  |    NONE    | (2) 64K x  |    NONE    |
   |        |     8      |            |     4      |            |
   |--------+------------+------------+------------+------------|
   | 128KB  | (4) 32K x  |    NONE    |    NONE    | (1) 32K x  |
   |        |     8      |            |            |     8      |
   |--------+------------+------------+------------+------------|
   | 256KB  | (4) 32K x  | (4) 32K x  | (2) 16K x  |    NONE    |
   |        |     8      |     8      |     4      |            |
   |--------+------------+------------+------------+------------|
   | 256KB  | (4) 32K x  | (4) 32K x  |    NONE    | (1) 32K x  |
   |        |     8      |     8      |            |     8      |
   |--------+------------+------------+------------+------------|
   | 512KB  | (4) 128K x |    NONE    |    NONE    | (1) 128K x |
   |        |     8      |            |            |     8      |
   |--------+------------+------------+------------+------------|
   | 1024KB | (4) 128K x | (4) 128K x | (2) 64K x  |    NONE    |
   |        |     8      |     8      |     4      |            |
   |--------+------------+------------+------------+------------|
   | 1024KB | (4) 128K x | (4) 128K x |    NONE    | (1) 128K x |
   |        |     8      |     8      |            |     8      |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 CACHE JUMPER CONFIGURATION                 |
   |------------------------------------------------------------|
   |  Size  | JP28  |  JP30  |  JP31  | JPX1/JPX2 | JPX3 | JPX4 |
   |--------+-------+--------+--------+-----------+------+------|
   |  32KB  | 2 & 3 |  Open  | Closed |   1 - 8   | Open | 1 -  |
   |        |       |        |        |           |      |  16  |
   |--------+-------+--------+--------+-----------+------+------|
   |  64KB  | 1 & 2 | Closed |  Open  |   1 - 8   | 1 -  | Open |
   |        |       |        |        |           |  16  |      |
   |--------+-------+--------+--------+-----------+------+------|
   | 128KB  | 1 & 2 | Closed | Closed |  3 - 10   | 1 -  | Open |
   |        |       |        |        |           |  16  |      |
   |--------+-------+--------+--------+-----------+------+------|
   | 256KB  | 1 & 2 | Closed |  Open  |  5 - 12   | 1 -  | Open |
   |        |       |        |        |           |  16  |      |
   |--------+-------+--------+--------+-----------+------+------|
   | 512KB  | 1 & 2 | Closed |  Open  |  7 - 14   | Open | 1 -  |
   |        |       |        |        |           |      |  16  |
   |--------+-------+--------+--------+-----------+------+------|
   | 1024KB | 1 & 2 | Closed | Closed |  9 - 18   | 1 -  | Open |
   |        |       |        |        |           |  16  |      |
   |------------------------------------------------------------|
   | Note: Jumpers JPX1-JPX4 are closed using one or two 8-pin  |
   | terminating resistors.                                     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                   CPU TYPE CONFIGURATION                   |
   |------------------------------------------------------------|
   |        Type        |       JP25        |       JPX5        |
   |--------------------+-------------------+-------------------|
   |      80486SX       |      Closed       |       Open        |
   |--------------------+-------------------+-------------------|
   |      80486DX       |       Open        |      Closed       |
   +------------------------------------------------------------+