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

[Image]

                                CONNECTIONS

  Purpose                   Location   Purpose                   Location

  Turbo LED                   D6       Reset                      JP20

  External battery           JP15      Speaker                    JP21

  Turbo switch               JP19      Power LED & keylock        JP22

                        USER CONFIGURABLE SETTINGS

                Function                     Jumper          Position

  »   Factory configured - do not alter        JP2             Open

  »   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 alter        JP6           pins 1 & 2
                                                              closed

  »   Factory configured - do not alter        JP8           pins 1 & 2
                                                              closed

  »   Factory configured - do not alter       JP14           pins 1 & 2
                                                              closed

  »   Factory configured - do not alter       JP17           pins 1 & 2
                                                              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 4       NONE

     32KB        (4) 8K x 8        NONE          NONE        (1) 8K x 8

     64KB        (4) 8K x 8     (4) 8K x 8    (2) 16K x 4       NONE

     64KB        (4) 8K x 8     (4) 8K x 8       NONE        (1) 8K x 8

     128KB       (4) 32K x 8       NONE       (2) 64K x 4       NONE

     128KB       (4) 32K x 8       NONE          NONE        (1) 32K x 8

     256KB       (4) 32K x 8    (4) 32K x 8   (2) 16K x 4       NONE

     256KB       (4) 32K x 8    (4) 32K x 8      NONE        (1) 32K x 8

     512KB        (4) 128K x       NONE          NONE       (1) 128K x 8
                      8

    1024KB        (4) 128K x    (4) 128K x    (2) 64K x 4       NONE
                      8             8

    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 - 16    Open

   128KB     1 & 2     Closed     Closed      3 - 10      1 - 16    Open

   256KB     1 & 2     Closed      Open       5 - 12      1 - 16    Open

   512KB     1 & 2     Closed      Open       7 - 14      Open     1 - 16

  1024KB     1 & 2     Closed     Closed      9 - 18      1 - 16    Open

  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