
ABIT COMPUTER CORPORATION

AH4/AH4T (REV. 1.2)

Processor  80486SX/SL80486SX/CX486M7/80486DX/SL80486DX/CX486DX2/AM486DX2/80486DX2/SL80486DX2/AM486DX4/80486DX4
Processor  20/25/33/40/50(internal)/66(internal)/75(internal)/100(internal)MHz
Speed
Chip Set   Unidentifed
Max.       128MB
Onboard
DRAM
Cache      128/256/512KB
BIOS       Award
Dimensions 330mm x 218mm
I/O        32-bit VESA local bus slots (3), green PC connector
Options
NPU        None
Options

[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

  
      CMOS memory normal operation
                                              JP16
                                                            pins 1 & 2
                                                              closed


      CMOS memory clear
                                              JP16
                                                            pins 2 & 3
                                                              closed

  
      Factory configured - do not
      alter
                                              JP17
                                                               N/A

  
      Factory configured - do not
      alter
                                              JP19
                                                            pins 1 & 2
                                                              closed

  
      Factory configured - do not
      alter
                                              JP23
                                                            pins 1 & 2
                                                              closed

  
      Factory configured - do not
      alter
                                              JP26
                                                               Open

  
      Factory configured - do not
      alter
                                              JP30
                                                               N/A

  
      Factory configured - do not
      alter
                                              JP31
                                                               N/A

  
      Factory configured - do not
      alter
                                              JP42
                                                              Closed

  Note: The locations of JP19, JP23 & JP42 are unidentified.

                            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
                      36
                                 (1) 16M x
                                    36
                                                  NONE
                                                                 NONE

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

     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
                                                   36
                                                                 NONE

     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
                                    36
                                                  NONE
                                                                 NONE

     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
                                                   36
                                                                 NONE

     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
                                    36
                                                  NONE
                                                                 NONE

     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

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

    SL80486SX       2 & 3       Open        Open       3 & 4      2 & 3

     CX486M7        1 & 2      Closed       2 & 3      2 & 3     1 & 2, 3
                                                                   & 4

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

    SL80486DX       1 & 2      Closed       2 & 3      3 & 4      2 & 3

    CX486DX2        1 & 2      Closed       2 & 3      2 & 3     1 & 2, 3
                                                                   & 4

    AM486DX2        1 & 2      Closed       2 & 3      3 & 4      2 & 3

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

   SL80486DX2       1 & 2      Closed       2 & 3      3 & 4      2 & 3

    AM486DX4        1 & 2      Closed       2 & 3      3 & 4      2 & 3

    80486DX4        1 & 2      Closed       2 & 3      3 & 4      2 & 3

  Note: Pins designated should be in the closed position. SL80486DX/DX2
  is only available on the AH4T mainboard

                          CPU TYPE CONFIGURATION

      Type
                     JP15
                                JP21
                                            JP22
                                                       JP24
                                                                  JP25

     80486SX
                    4 & 5
                                2 & 3
                                           1 & 2
                                                       Open
                                                                  Open

    SL80486SX
                    4 & 5
                                2 & 3
                                           1 & 2
                                                       Open
                                                                  Open

     CX486M7
                    2 & 3
                                1 & 2
                                           2 & 3
                                                      2 & 3
                                                                  2 & 3

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

    SL80486DX
                    4 & 5
                                2 & 3
                                           1 & 2
                                                       Open
                                                                  Open

    CX486DX2
                    2 & 3
                                1 & 2
                                           2 & 3
                                                      2 & 3
                                                                  2 & 3

    AM486DX2
                    4 & 5
                                2 & 3
                                           1 & 2
                                                       Open
                                                                  Open

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

   SL80486DX2
                    4 & 5
                                2 & 3
                                           1 & 2
                                                       Open
                                                                  Open

    AM486DX4
                    4 & 5
                                2 & 3
                                           1 & 2
                                                       Open
                                                                  Open

    80486DX4
                    4 & 5
                                2 & 3
                                           1 & 2
                                                       Open
                                                                  Open

  Note: Pins designated should be in the closed position. SL80486DX/DX2
  is only available on the AH4T mainboard

                          CPU TYPE CONFIGURATION

      Type        JP32     JP46      JP48     JP49     JP50       JP62

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

   SL80486SX     1 & 2     2 & 3    2 & 3     Open     2 & 3      Open

    CX486M7      1 & 2     1 & 2    2 & 3     Open     2 & 3      Open

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

   SL80486DX     1 & 2     2 & 3    2 & 3     Open     2 & 3      Open

    CX486DX2     1 & 2     1 & 2    1 & 2     Open     1 & 2      Open

    AM486DX2     1 & 2     2 & 3    1 & 2     Open     1 & 2      Open

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

   SL80486DX2    1 & 2     2 & 3    2 & 3     Open     2 & 3      Open

    AM486DX4     1 & 2     2 & 3    1 & 2     1 & 2    1 & 2     Closed

    80486DX4      Open     2 & 3    1 & 2     1 & 2    1 & 2      Open

  Note: Pins designated should be in the closed position. SL80486DX/DX2
  is only available on the AH4T mainboard

          CPU SPEED CONFIGURATION

   Speed
              JP5
                         JP6
                                    JP7

   20MHz
             Closed
                         Open
                                  Closed

   25MHz
             Closed
                        Closed
                                   Open

   33MHz
              Open
                        Closed
                                  Closed

   40MHz
             Closed
                         Open
                                   Open

  50iMHz
             Closed
                        Closed
                                   Open

  66iMHz
              Open
                        Closed
                                  Closed

  75iMHz
             Closed
                        Closed
                                   Open

  100iMHz
              Open
                        Closed
                                  Closed

              CPU VOLTAGE CONFIGURATION

  Voltage     JP53       JP54      JP55       JP56

   3.3v      Closed      Open      Open       Open

   3.45v      Open      Closed     Open       Open

   3.6v       Open       Open     Closed      Open

    4v        Open       Open      Open      Closed

         BUS SPEED CONFIGURATION

      CPU speed
                             JP29

      <= 33MHz
                      pins 1 & 2 closed

       > 33MHz
                      pins 2 & 3 closed

