
DELL COMPUTER CORPORATION

Precision 486SX/25, Precision 486DX/33

Processor         80486SX/80487SX/80486DX
Processor Speed   25/33MHz
Chip Set          OPTI
Max. Onboard DRAM 32MB
Cache             64/256KB
BIOS              AMI
Dimensions        330mm x 218mm
I/O Options       None
NPU Options       None

[Image]

                                CONNECTIONS

  Purpose                Location      Purpose                 Location

  Reset switch              J9         Speaker                   J21

  External battery          J18        Power LED & keylock       J22

  Turbo switch              J20

  Note:Although there is a 4167 socket on the board, it is not supported.
  (As per the manufacturer)

                        USER CONFIGURABLE SETTINGS

                Function                     Jumper          Position

     Battery select internal                  W1             Closed

      Battery select external                  W1              Open

     CMOS memory normal operation             W2            pins 1 & 2
                                                              closed

      CMOS memory clear                        W2            pins 2 & 3
                                                              closed

     CPU speed select ATCLK/4                 W3            pins 2 & 3
                                                              closed

      CPU speed select ATCLK/6                 W3            pins 1 & 2
                                                              closed

     Factory configured - do not alter        W8              Open

     Factory configured - do not alter        W9              Open

     Factory configured - do not alter        W10             Open

     Monitor type select color                W12           pins 1 & 2
                                                              closed

      Monitor type select monochrome           W12           pins 2 & 3
                                                              closed

     Factory test disabled                    W13             Open

      Factory test enabled                     W13           pins 1 & 2
                                                              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

      20MB        (4) 4M x 9     (4) 256K x 9

      32MB        (4) 4M x 9      (4) 1M x 9

     CACHE CONFIGURATION

     Size          Bank 0

     64KB        (8) 8K x 8

     256KB      (8) 32K x 8

                        CACHE JUMPER CONFIGURATION

      Size               W8                 W9                 W18

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

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

                          CPU TYPE CONFIGURATION

       Type               W5                 W6                 W7

     80486SX           pins 2 & 3        pins 2 & 3            Open
                        closed             closed

     80487SX           pins 1 & 2        pins 1 & 2         pins 1 & 2
                        closed             closed             closed

     80486DX           pins 1 & 2        pins 1 & 2         pins 2 & 3
                        closed             closed             closed

