
SCI SYSTEMS, INC.

SCI 486SX/DX SYSTEM BOARD

Processor             80486SX/80486DX
Processor Speed       25/33MHz
Chip Set              OPTI
Max. Onboard DRAM     64MB
Cache                 64/256KB
BIOS                  Unidentified
Dimensions            330mm x 218mm
I/O Options           Floppy drive interface, IDE interface, parallel
                      port, PS/2 mouse port, serial ports (2), VGA port
NPU Options           None

[Image]

                                CONNECTIONS

  Purpose                   Location   Purpose                   Location

  PS/2 mouse port             J1       IDE interface LED           J23

  IDE interface               J5       Reset switch                J24

  Floppy drive interface      J6       Speaker                     J25

  Parallel port               J8       Power LED & keylock         J26

  Serial port 2               J9       VGA port                    J27

  Serial port 1               J10

                        USER CONFIGURABLE SETTINGS

              Function                  Jumper/Switch        Position

     Monitor type select color              W1              pins 1 & 2
                                                              closed

      Monitor type select                    W1              pins 2 & 3
      monochrome                                              closed

     CMOS memory normal operation           W2              pins 1 & 2
                                                              closed

      CMOS memory clear                      W2              pins 2 & 3
                                                              closed

     SYSCLK enabled                         W3              pins 2 & 3
                                                              closed

      SYSCLK/2 enabled                       W3              pins 1 & 2
                                                              closed

     On board VGA enabled                   W10             pins 1 & 2
                                                              closed

      On board VGA disabled                  W10             pins 2 & 3
                                                              closed

     Video horizontal scan rate            SW1/5               On
      select 31.5 kHz

      Video horizontal scan rate            SW1/5               Off
      select 40kHz

     Video memory select 512KB             SW1/6               On

      Video memory select 1MB               SW1/6               Off

                            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

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

     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

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

     9MB         (1) 256K x    (1) 1M x 36     (1) 1M x 36       NONE
                    36

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

     13MB        (1) 256K x    (1) 1M x 36     (1) 1M x 36   (1) 1M x 36
                    36

     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

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

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

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

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

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

     28MB       (1) 1M x 36    (1) 1M x 36     (1) 4M x 36   (1) 1M x 36

     28MB       (1) 1M x 36    (1) 4M x 36     (1) 1M x 36   (1) 1M x 36

     28MB       (1) 4M x 36    (1) 1M x 36     (1) 1M x 36   (1) 1M x 36

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

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

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

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

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

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

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

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

                       DRAM CONFIGURATION (CONT)

     Size         Bank 0         Bank 1         Bank 2        Bank 3

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

     52MB       (1) 1M x 36   (1) 4M x 36    (1) 4M x 36    (1) 4M x 36

     52MB       (1) 4M x 36   (1) 1M x 36    (1) 4M x 36    (1) 4M x 36

     52MB       (1) 4M x 36   (1) 4M x 36    (1) 4M x 36    (1) 1M x 36

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

                    CACHE CONFIGURATION

     Size          Bank 0         Bank 1          TAG

     64KB        (4) 8K x 8     (4) 8K x 8    (2) 16K x 4

     256KB      (4) 32K x 8    (4) 32K x 8    (2) 16K x 4

                        CACHE JUMPER CONFIGURATION

    Size          W4              W5             W9              W11

    64KB       pins 2 & 3     pins 2 & 3      pins 2 & 3      pins 2 & 3
                closed          closed         closed          closed

   256KB       pins 1 & 2     pins 1 & 2      pins 1 & 2      pins 2 & 3
                closed          closed         closed          closed

                          CPU TYPE CONFIGURATION

      Type               W6                 W7                 W8

      486SX           pins 2 & 3        pins 2 & 3             N/A
                       closed             closed

      487SX           pins 1 & 2        pins 1 & 2      pins 1 & 2 closed
                       closed             closed

      486DX           pins 1 & 2        pins 1 & 2      pins 2 & 3 closed
                       closed             closed

                      VIDEO CONFIGURATION (800 X 600)

       Refresh rate                 SW1/1                   SW1/2

             60Hz                   Off                     On

              56Hz                   Off                     Off

              56Hz                    On                     On

              72Hz                    On                     Off

                     VIDEO CONFIGURATION (1024 X 768)

         Refresh rate                  SW1/3                 SW1/4

            Interlaced                 Off                   Off

                60Hz                    Off                   On

                70Hz                     On                   Off

                72Hz                     On                   On

                  VIDEO MEMORY CONFIGURATION

        Size                Bank 0               Bank 1

        512KB            (4) 256K x 4             NONE

         1MB             (4) 256K x 4         (4) 256K x 4

  Note: Bank 0 is factory installed and is not configurable.

