
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

[Image]

                                CONNECTIONS

  Purpose                   Location   Purpose                   Location

  Power LED & keylock         J1       Reset switch                J4

  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    (1) 16K x 4    (1) 8K x 8

     128KB      (4) 32K x 8       Bank 0      (1) 16K x 4    (1) 32K x 8

     256KB      (8) 32K x 8    Banks 0 & 1    (1) 16K x 4    (1) 32K x 8

                         CPU JUMPER CONFIGURATION

        CPU            Jumper W10          Jumper W11        Jumper W14

      80486DX          pins 1 & 2      pins 1 & 2 and 3 &       open
                         closed             4 closed

      80487SX          pins 2 & 3      pins 1 & 2 and 3 &      closed
                         closed             4 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 closed
            256K x
              9

   1MB      NONE       NONE     (1) 256K    NONE      pins 2 & 3 closed
                                 x 36

   2MB       (4)        (4)      NONE       NONE      pins 1 & 2 closed
            256K x    256K x
              9         9

   2MB      NONE       NONE     (1) 256K   (1) 256K   pins 2 & 3 closed
                                 x 36       x 36

   3MB       (4)        (4)     (1) 256K    NONE      pins 1 & 2 closed
            256K x    256K x     x 36
              9         9

   4MB       (4)        (4)     (1) 256K   (1) 256K   pins 1 & 2 closed
            256K x    256K x     x 36       x 36
              9         9

   4MB      (4) 1M     NONE      NONE       NONE      pins 1 & 2 closed
             x 9

   4MB      NONE       NONE     (1) 1M x    NONE      pins 2 & 3 closed
                                  36

   5MB       (4)      (4) 1M     NONE       NONE      pins 1 & 2 closed
            256K x     x 9
              9

   8MB      (4) 1M    (4) 1M     NONE       NONE      pins 1 & 2 closed
             x 9       x 9

   8MB      NONE       NONE     (1) 1M x   (1) 1M x   pins 2 & 3 closed
                                  36         36

  12MB      (4) 1M    (4) 1M    (1) 1M x    NONE      pins 1 & 2 closed
             x 9       x 9        36

  16MB      (4) 1M    (4) 1M    (1) 1M x   (1) 1M x   pins 1 & 2 closed
             x 9       x 9        36         36

  16MB      (4) 4M     NONE      NONE       NONE      pins 1 & 2 closed
             x 9

  16MB      NONE       NONE     (1) 4M x    NONE      pins 2 & 3 closed
                                  36

  20MB      (4) 1M    (4) 4M     NONE       NONE      pins 1 & 2 closed
             x 9       x 9

  32MB      (4) 4M    (4) 4M     NONE       NONE      pins 1 & 2 closed
             x 9       x 9

  32MB      NONE       NONE     (1) 4M x   (1) 4M x   pins 2 & 3 closed
                                  36         36

  48MB      (4) 4M    (4) 4M    (1) 4M x    NONE      pins 1 & 2 closed
             x 9       x 9        36

  64MB      (4) 4M    (4) 4M    (1) 4M x   (1) 4M x   pins 1 & 2 closed
             x 9       x 9        36         36

  Note:The locations of jumpers W12, W13, W15,and W16 are unknown.

