
UNIDENTIFIED

50/33/25/20MHZ MAINBOARD

Processor         80486SX/80487SX/80486DX/80486DX2
Processor Speed   20/25/33/40/50 (Internal) /50/66 (Internal)
Chip Set          C & T
Max. onboard DRAM 32MB
Cache             64/128/256KB
BIOS              AMI
Dimensions        330mm x 218mm
I/O Options       None
NPU Options       None

[Image]

                                CONNECTIONS

  Purpose                   Location   Purpose                   Location

  Power LED & keylock         J17      External battery            J20

  Speaker                     J18      Turbo switch                J21

  Reset switch                J19      Turbo LED                   J22

                        USER CONFIGURABLE SETTINGS

              Function                  Jumper/Switch         Position

     Monitor type select                    JP3                Open
      monochrome

      Monitor type select color              JP3               Closed

     CMOS memory normal operation           JP5             Pins 1 & 2
                                                               closed

      CMOS memory clear                      JP5             Pins 2 & 3
                                                               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

      5MB         (4) 256K x 9    (4) 1M x 9

      8MB         (4) 1M x 9      (4) 1M x 9

      16MB        (4) 4M x 9         NONE

      20MB        (4) 1M x 9      (4) 4M x 9

      32MB        (4) 4M x 9      (4) 4M x 9

                            CACHE CONFIGURATION

     Size        Max Cachable      Bank 0        Bank 1          TAG

     64KB            16MB        (4) 8K x 8    (4) 8K x 8     (1) 8K x 8

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

     256KB           64MB        (4) 32K x 8   (4) 32K x 8    (1) 32K x 8

                  CACHE JUMPER CONFIGURATION

        Size                 JP24                 JP25

        64KB                 Open                 Open

        128KB          Pins 1 & 2 closed   Pins 1 & 2 closed

        256KB          Pins 2 & 3 closed   Pins 2 & 3 closed

                CPU SPEED CONFIGURATION

           Speed                       JP21

       80486SX/20MHz             Pins 5 & 6 closed

       80486SX/25MHz         Pins 1 & 2, 5 & 6 closed

       80486SX/33MHz         Pins 1 & 2, 3 & 4 closed

       80487SX/20MHz             Pins 5 & 6 closed

       80486DX/25MHz         Pins 1 & 2, 5 & 6 closed

       80486DX/33MHz         Pins 1 & 2, 3 & 4 closed

       80486DX/40MHz             Pins 5 & 6 closed

       80486DX/50MHz             Pins 3 & 4 closed

      80486DX2/50i MHz       Pins 1 & 2, 5 & 6 closed

      80486DX2/66i MHz       Pins 1 & 2, 3 & 4 closed

                          CPU TYPE CONFIGURATION

        TYPE              JP9         JP11         JP12          JP13

    80486SX/20MHz      Pins 2 & 3     Open       Pins 2 & 3    Pins 2 & 3
                        closed                    closed        closed

    80486SX/25MHz      Pins 1 & 2     Open       Pins 2 & 3    Pins 2 & 3
                        closed                    closed        closed

    80486SX/33MHz      Pins 1 & 2     Open       Pins 2 & 3    Pins 2 & 3
                        closed                    closed        closed

    80487SX/20MHz      Pins 2 & 3    Closed      Pins 2 & 3    Pins 1 & 2
                        closed                    closed        closed

    80486DX/25MHz      Pins 1 & 2    Closed      Pins 1 & 2    Pins 1 & 2
                        closed                    closed        closed

    80486DX/33MHz      Pins 1 & 2    Closed      Pins 1 & 2    Pins 1 & 2
                        closed                    closed        closed

    80486DX/40MHz      Pins 1 & 2    Closed      Pins 1 & 2    Pins 1 & 2
                        closed                    closed        closed

    80486DX/50MHz      Pins 1 & 2    Closed      Pins 1 & 2    Pins 1 & 2
                        closed                    closed        closed

  80486DX2/50i MHz     Pins 1 & 2    Closed      Pins 1 & 2    Pins 1 & 2
                        closed                    closed        closed

  80486DX2/66i MHz     Pins 1 & 2    Closed      Pins 1 & 2    Pins 1 & 2
                        closed                    closed        closed

