
J-MARK COMPUTER CORPORATION

486SX/DX VERSION II

Processor           80486SX/80487SX/80486DX/80486DX2
Processor Speed     16/20/25/33/50(internal)/50/66(internal) MHz
Chip Set            OPTI
Max. onboard DRAM   32MB
Cache               64/128/256KB
BIOS                AMI
Dimensions          240mm x 220mm
I/O Options         None
NPU Options         None

[Image]

                                CONNECTIONS

  Purpose                   Location   Purpose                   Location

  External battery            J1       Speaker                     J17

  Turbo switch                JP9      Power LED & keylock         J18

  Turbo LED                  JP10      Reset switch                SW1

                        USER CONFIGURABLE SETTINGS

                Function                     Jumper          Position

     CMOS memory normal operation             JP1           pins 1 & 2
                                                              closed

      CMOS memory clear                        JP1           pins 2 & 3
                                                              closed

     Monitor type select color                JP2            Closed

      Monitor type select monochrome           JP2             Open

              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          Bank 0         Bank 1       TAG (U39)      TAG (U40)

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

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

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

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

                        CACHE JUMPER CONFIGURATION

   Size       JP5        JP6        JP7       JP8      JP15        JP16

   64KB      Open       Open       Open      pins 2    Open        Open
                                              & 3

  128KB     Closed      Open      Closed     pins 1    Open       Closed
                                              & 2

  256KB     Closed     Closed     Closed     pins 2   closed      closed
                                              & 3

  Note:Pins designated should be in the closed postion.

                          CPU TYPE CONFIGURATION

     CPU type          JP17          JP18          JP19          JP20

   80486SX PQFP        Open          Open         Closed      pins 2 & 3
                                                                closed

   80486SX PGA        Closed         Open         Closed      pins 2 & 3
                                                                closed

     80487SX          Closed      pins 2 & 3      Closed      pins 1 & 2
                                    closed                      closed

   80486DX/DX2        Closed      pins 1 & 2      Closed      pins 1 & 2
                                    closed                      closed

               CPU SPEED CONFIGURATION

   Speed      JP11       JP12      JP13       JP14

   16MHz     Closed     Closed    Closed     Closed

   20MHz      Open      Closed    Closed      Open

   25MHz      Open      Closed     Open      Closed

   33MHz      Open       Open     Closed      Open

  50i MHz     Open      Closed     Open      Closed

   50MHz      Open       Open     Closed      Open

  66i MHz     Open       Open     Closed      Open

