ABC COMPUTER COMPANY, LTD.
==========================

   A4879

   Processor          80486SX/80487SX/80486DX                     
   Processor Speed    25/50MHz                                    
   Chip Set           UMC                                         
   Max. Onboard DRAM  64MB                                        
   SRAM Cache         64/128/256KB                                
   BIOS               AMI                                         
   Dimensions         220mm x 330mm                               
   I/O Options        None                                        
   NPU Options        4167                                        

<gopher://bitreich.org/I/th99/m/A-B/31282-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   | Purpose           | Location | Purpose          | Location |
   |-------------------+----------+------------------+----------|
   | Power LED &       |    J1    | Reset switch     |    J4    |
   | keylock           |          |                  |          |
   |-------------------+----------+------------------+----------|
   | Speaker           |    J2    | Turbo LED        |    J5    |
   |-------------------+----------+------------------+----------|
   | Turbo switch      |    J3    | External battery |    J6    |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 USER CONFIGURABLE SETTINGS                 |
   |------------------------------------------------------------|
   |               Function               | Jumper  | Position  |
   |--------------------------------------+---------+-----------|
   |>> | Monitor type select color        |   W18   |  closed   |
   |---+----------------------------------+---------+-----------|
   |   | Monitor type select monochrome   |   W18   |   open    |
   |---+----------------------------------+---------+-----------|
   |>> | Battery type select internal     |   W22   |  closed   |
   |---+----------------------------------+---------+-----------|
   |   | Battery type select external     |   W22   |   open    |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 SRAM JUMPER CONFIGURATION                  |
   |------------------------------------------------------------|
   | Jumper |      64KB       |     128KB      |     256KB      |
   |--------+-----------------+----------------+----------------|
   |   W2   |   pins 1 & 2    |   pins 2 & 3   |   pins 2 & 3   |
   |        |     closed      |     closed     |     closed     |
   |--------+-----------------+----------------+----------------|
   |   W3   |   pins 1 & 2    |   pins 1 & 2   |   pins 2 & 3   |
   |        |     closed      |     closed     |     closed     |
   |--------+-----------------+----------------+----------------|
   |   W4   |      open       |   pins 2 & 3   |   pins 2 & 3   |
   |        |                 |     closed     |     closed     |
   |--------+-----------------+----------------+----------------|
   |   W5   |   pins 1 & 2    |   pins 1 & 2   |   pins 1 & 2   |
   |        |     closed      |     closed     |     closed     |
   |--------+-----------------+----------------+----------------|
   |   W6   |      open       |     closed     |     closed     |
   |--------+-----------------+----------------+----------------|
   |   W7   |      open       |      open      |     closed     |
   |--------+-----------------+----------------+----------------|
   |   W8   |      open       |      open      |     closed     |
   |--------+-----------------+----------------+----------------|
   |   W9   |      open       |     closed     |     closed     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     SRAM CONFIGURATION                     |
   |------------------------------------------------------------|
   | Size  | Cache SRAM  |  Location  | TAG (U10)  | TAG (U11)  |
   |-------+-------------+------------+------------+------------|
   | 64KB  | (8) 8K x 8  | Banks 0 &  | (1) 16K x  | (1) 8K x 8 |
   |       |             |     1      |     4      |            |
   |-------+-------------+------------+------------+------------|
   | 128KB | (4) 32K x 8 |   Bank 0   | (1) 16K x  | (1) 32K x  |
   |       |             |            |     4      |     8      |
   |-------+-------------+------------+------------+------------|
   | 256KB | (8) 32K x 8 | Banks 0 &  | (1) 16K x  | (1) 32K x  |
   |       |             |     1      |     4      |     8      |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                  CPU JUMPER CONFIGURATION                  |
   |------------------------------------------------------------|
   |   CPU   | Jumper W10  |        Jumper W11        | Jumper  |
   |         |             |                          |   W14   |
   |---------+-------------+--------------------------+---------|
   | 80486DX | pins 1 & 2  |   pins 1 & 2 and 3 & 4   |  open   |
   |         |   closed    |          closed          |         |
   |---------+-------------+--------------------------+---------|
   | 80487SX | pins 2 & 3  |   pins 1 & 2 and 3 & 4   | closed  |
   |         |   closed    |          closed          |         |
   |---------+-------------+--------------------------+---------|
   | 80486SX |    open     |    pins 2 & 3 closed     | closed  |
   |------------------------------------------------------------|
   | Note:The location of W14 is unknown.                       |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     DRAM CONFIGURATION                     |
   |------------------------------------------------------------|
   | Size | Bank 0 | Bank 1 | Bank 2 | Bank 3 |     Jumpers     |
   |      |        |        |        |        |                 |
   |      |        |        |        |        | W12,W13,W15,W16 |
   |------+--------+--------+--------+--------+-----------------|
   | 1MB  |  (4)   |  NONE  |  NONE  |  NONE  |   pins 1 & 2    |
   |      | 256K x |        |        |        |     closed      |
   |      |   9    |        |        |        |                 |
   |------+--------+--------+--------+--------+-----------------|
   | 1MB  |  NONE  |  NONE  |  (1)   |  NONE  |   pins 2 & 3    |
   |      |        |        | 256K x |        |     closed      |
   |      |        |        |   36   |        |                 |
   |------+--------+--------+--------+--------+-----------------|
   | 2MB  |  (4)   |  (4)   |  NONE  |  NONE  |   pins 1 & 2    |
   |      | 256K x | 256K x |        |        |     closed      |
   |      |   9    |   9    |        |        |                 |
   |------+--------+--------+--------+--------+-----------------|
   | 2MB  |  NONE  |  NONE  |  (1)   |  (1)   |   pins 2 & 3    |
   |      |        |        | 256K x | 256K x |     closed      |
   |      |        |        |   36   |   36   |                 |
   |------+--------+--------+--------+--------+-----------------|
   | 3MB  |  (4)   |  (4)   |  (1)   |  NONE  |   pins 1 & 2    |
   |      | 256K x | 256K x | 256K x |        |     closed      |
   |      |   9    |   9    |   36   |        |                 |
   |------+--------+--------+--------+--------+-----------------|
   | 4MB  |  (4)   |  (4)   |  (1)   |  (1)   |   pins 1 & 2    |
   |      | 256K x | 256K x | 256K x | 256K x |     closed      |
   |      |   9    |   9    |   36   |   36   |                 |
   |------+--------+--------+--------+--------+-----------------|
   | 4MB  | (4) 1M |  NONE  |  NONE  |  NONE  |   pins 1 & 2    |
   |      |  x 9   |        |        |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 4MB  |  NONE  |  NONE  | (1) 1M |  NONE  |   pins 2 & 3    |
   |      |        |        |  x 36  |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 5MB  |  (4)   | (4) 1M |  NONE  |  NONE  |   pins 1 & 2    |
   |      | 256K x |  x 9   |        |        |     closed      |
   |      |   9    |        |        |        |                 |
   |------+--------+--------+--------+--------+-----------------|
   | 8MB  | (4) 1M | (4) 1M |  NONE  |  NONE  |   pins 1 & 2    |
   |      |  x 9   |  x 9   |        |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 8MB  |  NONE  |  NONE  | (1) 1M | (1) 1M |   pins 2 & 3    |
   |      |        |        |  x 36  |  x 36  |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 12MB | (4) 1M | (4) 1M | (1) 1M |  NONE  |   pins 1 & 2    |
   |      |  x 9   |  x 9   |  x 36  |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 16MB | (4) 1M | (4) 1M | (1) 1M | (1) 1M |   pins 1 & 2    |
   |      |  x 9   |  x 9   |  x 36  |  x 36  |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 16MB | (4) 4M |  NONE  |  NONE  |  NONE  |   pins 1 & 2    |
   |      |  x 9   |        |        |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 16MB |  NONE  |  NONE  | (1) 4M |  NONE  |   pins 2 & 3    |
   |      |        |        |  x 36  |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 20MB | (4) 1M | (4) 4M |  NONE  |  NONE  |   pins 1 & 2    |
   |      |  x 9   |  x 9   |        |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 32MB | (4) 4M | (4) 4M |  NONE  |  NONE  |   pins 1 & 2    |
   |      |  x 9   |  x 9   |        |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 32MB |  NONE  |  NONE  | (1) 4M | (1) 4M |   pins 2 & 3    |
   |      |        |        |  x 36  |  x 36  |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 48MB | (4) 4M | (4) 4M | (1) 4M |  NONE  |   pins 1 & 2    |
   |      |  x 9   |  x 9   |  x 36  |        |     closed      |
   |------+--------+--------+--------+--------+-----------------|
   | 64MB | (4) 4M | (4) 4M | (1) 4M | (1) 4M |   pins 1 & 2    |
   |      |  x 9   |  x 9   |  x 36  |  x 36  |     closed      |
   |------------------------------------------------------------|
   | Note:The locations of jumpers W12, W13, W15,and W16 are    |
   | unknown.                                                   |
   +------------------------------------------------------------+