
ISA/EISA, INC.

486B

Processor         80486SX/80487SX/80486DX
Processor Speed   20/33MHz
Chip Set          OPTI
Max. Onboard DRAM 32MB
SRAM Cache        64/256KB
BIOS              AMI
Dimensions        330mm x 218mm
I/O Options       None
NPU Options       4167

[Image]

                                CONNECTIONS

  Purpose                   Location    Purpose                  Location

  Power LED & keylock          J1       Turbo switch               JP2

  Speaker                      J3       Turbo LED                 JP21

  External battery             J4       Cooling fan switch        JP25

  Reset switch                JP1       Cooling fan power         USP8

                        USER CONFIGURABLE SETTINGS

                 Function                     Jumper         Position

     Factory configured - do not alter        JP10           unknown

     CPU speed select switchable at           JP12          pins 1 & 2
      keyboard                                                closed

      CPU speed select switchable at           JP12          pins 2 & 3
      turbo switch                                            closed

     Factory configured - do not alter        JP26            open

     Video BIOS shadow before                 JP27          pins 1 & 2
      initialization                                          closed

      Video BIOS shadow after                  JP27          pins 2 & 3
      initialization                                          closed

                         CPU JUMPER CONFIGURATION

        CPU              JP22              JP23               JP24

  80486DX (33MHz)      pins 1 & 2       pins 1 & 2     pins 1 & 2 and 3 &
                        closed            closed            4 closed

  80487SX (20MHz)      pins 3 & 4       pins 2 & 3     pins 1 & 2 and 3 &
                        closed            closed            4 closed

  80486SX (20MHz)      pins 2 & 3       pins 2 & 3     pins 2 & 3 closed
                        closed            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) 1M x 9     (4) 256K x 9

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

      16MB        (4) 4M x 9         NONE

      17MB        (4) 4M x 9     (4) 256K x 9

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

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

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

                         SRAM JUMPER CONFIGURATION

      Size          JP6         JP7        JP8         JP9         JP20

      64KB        pins 1 &    pins 1 &   pins 1 &    pins 1 &    pins 1 &
                     2           2          2           2           2

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

    Disabled        N/A         N/A        N/A         N/A       pins 2 &
                                                                    3

  Note:Pins designated should be in the closed position.

             SRAM CONFIGURATION

     Size        Cache SRAM        TAG

     64KB        (8) 8K x 8    (1) 8K x 8

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

                    I/O BUS SPEED JUMPER CONFIGURATION

    Bus       JP3        JP4       JP5       JP13       JP14       JP15
   Speed

   CPU/8      open      open       open      open       open      closed

   CPU/6      open      open       open      open      closed      open

   CPU/5      open      open       open     closed      open       open

   CPU/4      open      open      closed     open       open       open

   CPU/3      open     closed      open      open       open       open

   CPU/2     closed     open       open      open       open       open

