
ABIT COMPUTER CORPORATION

AH4

Processor        80486SX/80486DX/CX486DX2/80486DX2
Processor Speed  20/25/33/40/50(internal)/66(internal)MHz
Chip Set         SIS
Max. Onboard DRAM128MB
Cache            128/256/512KB
BIOS             Award
Dimensions       330mm x 218mm
I/O Options      32-bit VESA local bus slots (2), green PC connector
NPU Options      None

[Image]

                                CONNECTIONS

  Purpose                 Location      Purpose               Location

  External battery           J1         Reset switch             JW3

  Green PC connector     JP45 (pins 7   Turbo LED                JW4
                            - 8)

  Power LED & keylock        JW1        Turbo switch             JW5

  Speaker                    JW2        32-bit VESA local     SL1 - SL3
                                        bus slots

                        USER CONFIGURABLE SETTINGS

                Function                     Jumper          Position

     Factory configured - do not              J2              Open
      alter

     CMOS memory normal operation            JP16          pins 1 & 2
                                                              closed

      CMOS memory clear                       JP16          pins 2 & 3
                                                              closed

     Monitor type select color               JP17            Closed

      Monitor type select monochrome          JP17             Open

     Factory configured - do not             JP19             Open
      alter

     Factory configured - do not             JP26             Open
      alter

     Factory configured - do not             JP30             Open
      alter

     Factory configured - do not             JP31             Open
      alter

     Factory configured - do not             JP42             Open
      alter

                            DRAM CONFIGURATION

     Size         Bank 0         Bank 1         Bank 2          Bank 3

     1MB         (1) 256K x       NONE           NONE            NONE
                    36

     2MB         (1) 256K x     (1) 256K x       NONE            NONE
                    36             36

     2MB         (1) 512K x       NONE           NONE            NONE
                    36

     4MB         (1) 512K x     (1) 512K x       NONE            NONE
                    36             36

     4MB        (1) 1M x 36       NONE           NONE            NONE

     4MB         (1) 256K x     (1) 256K x     (1) 512K x        NONE
                    36             36             36

     5MB         (1) 256K x    (1) 1M x 36       NONE            NONE
                    36

     6MB         (1) 256K x     (1) 256K x    (1) 1M x 36        NONE
                    36             36

     6MB         (1) 512K x    (1) 1M x 36       NONE            NONE
                    36

     8MB         (1) 256K x     (1) 256K x     (1) 512K x    (1) 1M x 36
                    36             36             36

     8MB         (1) 512K x     (1) 512K x    (1) 1M x 36        NONE
                    36             36

     8MB        (1) 1M x 36    (1) 1M x 36       NONE            NONE

     8MB        (1) 2M x 36       NONE           NONE            NONE

     10MB        (1) 256K x     (1) 256K x    (1) 1M x 36    (1) 1M x 36
                    36             36

     12MB        (1) 512K x     (1) 512K x    (1) 1M x 36    (1) 1M x 36
                    36             36

     12MB       (1) 1M x 36    (1) 1M x 36    (1) 1M x 36        NONE

     16MB       (1) 2M x 36    (1) 2M x 36       NONE            NONE

     16MB       (1) 1M x 36    (1) 1M x 36    (1) 1M x 36    (1) 1M x 36

     16MB       (1) 4M x 36       NONE           NONE            NONE

     17MB        (1) 256K x    (1) 4M x 36       NONE            NONE
                    36

     18MB        (1) 256K x     (1) 256K x    (1) 4M x 36        NONE
                    36             36

     20MB        (1) 512K x     (1) 512K x    (1) 4M x 36        NONE
                    36             36

     20MB       (1) 1M x 36    (1) 4M x 36       NONE            NONE

     24MB       (1) 2M x 36    (1) 2M x 36    (1) 2M x 36        NONE

     24MB        (1) 512K x     (1) 512K x    (1) 1M x 36    (1) 4M x 36
                    36             36

     24MB       (1) 1M x 36    (1) 1M x 36    (1) 4M x 36        NONE

     32MB       (1) 2M x 36    (1) 2M x 36    (1) 2M x 36    (1) 2M x 36

     32MB       (1) 4M x 36    (1) 4M x 36       NONE            NONE

     32MB       (1) 8M x 36       NONE           NONE            NONE

     36MB        (1) 512K x     (1) 512K x    (1) 4M x 36    (1) 4M x 36
                    36             36

     36MB       (1) 1M x 36    (1) 4M x 36    (1) 4M x 36        NONE

                        DRAM CONFIGURATION (CONT)

     Size          Bank 0         Bank 1         Bank 2         Bank 3

     36MB        (1) 1M x 36    (1) 8M x 36       NONE           NONE

     40MB        (1) 1M x 36    (1) 1M x 36    (1) 4M x 36   (1) 4M x 36

     40MB        (1) 1M x 36    (1) 1M x 36    (1) 8M x 36       NONE

     48MB        (1) 4M x 36    (1) 4M x 36    (1) 4M x 36       NONE

     48MB        (1) 4M x 36    (1) 8M x 36       NONE           NONE

     64MB        (1) 4M x 36    (1) 4M x 36    (1) 4M x 36   (1) 4M x 36

     64MB        (1) 16M x 36      NONE           NONE           NONE

     64MB        (1) 4M x 36    (1) 4M x 36    (1) 8M x 36       NONE

     64MB        (1) 8M x 36    (1) 8M x 36       NONE           NONE

     65MB         (1) 256K x     (1) 16M x        NONE           NONE
                     36             36

     68MB        (1) 1M x 36     (1) 16M x        NONE           NONE
                                    36

     68MB        (1) 1M x 36    (1) 8M x 36    (1) 8M x 36       NONE

     72MB        (1) 1M x 36    (1) 1M x 36     (1) 16M x        NONE
                                                   36

     72MB        (1) 1M x 36    (1) 1M x 36    (1) 8M x 36   (1) 8M x 36

     80MB        (1) 4M x 36     (1) 16M x        NONE           NONE
                                    36

     80MB        (1) 4M x 36    (1) 8M x 36    (1) 8M x 36       NONE

     96MB        (1) 4M x 36    (1) 4M x 36     (1) 16M x        NONE
                                                   36

     96MB        (1) 4M x 36    (1) 4M x 36    (1) 8M x 36   (1) 8M x 36

     96MB        (1) 8M x 36    (1) 8M x 36    (1) 8M x 36       NONE

     128MB       (1) 16M x 36    (1) 16M x        NONE           NONE
                                    36

     128MB       (1) 8M x 36    (1) 8M x 36    (1) 8M x 36   (1) 8M x 36

                      CACHE CONFIGURATION

      Size          Bank 0          Bank 1           TAG

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

     256KB        (4) 32K x 8     (4) 32K x 8    (1) 32K x 8

     256KB        (4) 64K x 8        NONE        (1) 32K x 8

     512KB        (4) 64K x 8     (4) 64K x 8    (1) 32K x 8

     512KB       (4) 128K x 8        NONE        (1) 32K x 8

                 CACHE JUMPER CONFIGURATION

   Size       JP1       JP2       JP4       JP40      JP41

  128KB      1 & 2     1 & 2     1 & 2     1 & 2     1 & 2

  256KB      2 & 3     2 & 3     1 & 2     2 & 3     2 & 3

  256KB      1 & 2     2 & 3     1 & 2     1 & 2     1 & 2

  512KB      2 & 3     2 & 3     2 & 3     2 & 3     2 & 3

  512KB      1 & 2     2 & 3     2 & 3     1 & 2     1 & 2

  Note: Pins designated should be in the closed position.

                          CPU TYPE CONFIGURATION

     Type       JP8        JP9       JP11      JP12     JP14       JP15

   80486SX     2 & 3      Open       Open     3 & 4     2 & 3     4 & 5

   CX486DX     1 & 2     Closed     2 & 3     2 & 3     1 & 2,    2 & 3
                                                        3 & 4

   80486DX     1 & 2     Closed     2 & 3     3 & 4     2 & 3     4 & 5

   80486DX2    1 & 2     Closed     2 & 3     3 & 4     2 & 3     4 & 5

  Note: Pins designated should be in the closed position.

                   CPU TYPE CONFIGURATION (CONT)

    Type       JP21        JP22       JP24        JP25       JP46

  80486SX      2 & 3      1 & 2       Open        Open       2 & 3

  CX486DX      1 & 2      2 & 3       2 & 3       2 & 3      1 & 2

  80486DX      2 & 3      1 & 2       Open        Open       2 & 3

  80486DX2     2 & 3      1 & 2       Open        Open       2 & 3

  Note: Pins designated should be in the closed position.

                          CPU SPEED CONFIGURATION

     Speed          JP5            JP6           JP7            JP20

     20MHz         Closed         Open          Closed        pins 1 & 2
                                                               closed

     25MHz         Closed        Closed          Open         pins 1 & 2
                                                               closed

     33MHz          Open         Closed         Closed        pins 1 & 2
                                                               closed

     40MHz         Closed         Open           Open         pins 2 & 3
                                                               closed

    50iMHz         Closed        Closed          Open         pins 1 & 2
                                                               closed

    66iMHz          Open         Closed         Closed        pins 1 & 2
                                                               closed

          BUS SPEEDCONFIGURATION

      CPU speed              JP29

       <=33MHz        pins 1 & 2 closed

       >33MHz         pins 2 & 3 closed

      VESA WAIT STATE CONFIGURATION

     Wait states             JP28

    0 wait states     pins 1 & 2 closed

    1 wait state      pins 2 & 3 closed

