AST RESEARCH, INC.

PREMIUM II 486SX/20 & 486SX/25

MODELS 202373-001 & 202373-002

Processor                  80486SX/80487SX (on external CPU/Memory module)
Processor Speed            20/25MHz
Chip Set                   AST
Max. Onboard DRAM          None (16MB on external CPU/Memory module)
Cache                      None
BIOS                       AST
Dimensions                 344mm x 250mm
I/O Options                32-bit external CPU/Memory module slot

                           32-bit external Memory module slot (2)

                           bus mouse port, floppy drive interface

                           IDE interface, parallel port, serial port (2),
                           SVGA port
NPU Options                4167 (on external CPU/Memory module)

[Image]

                                CONNECTIONS

  Purpose                    Location   Purpose                  Location

  SVGA port                    CN1      Front panel switches       P5
                                        & LEDs

  Bus mouse port               CN2      Speaker                    P6

  Serial port 1 (COM1)         CN3      External battery           P8

  Parallel port                CN4      IDE interface              P11

  Serial port 2 (COM2)         J15      Fan power                 P101

  VGA pass-through             J18      32-bit external            S1
                                        CPU/Memory module

  Floppy drive interface       P3       32-bit external            S2
                                        Memory module slot

  Third floppy drive           P4       32-bit external            S3
  interface                             Memory module slot

                        USER CONFIGURABLE SETTINGS

                 Function                   Switch SW1       Position

  »   VGA port enabled                       switch 1         closed

      VGA port disabled                      switch 1          open

  »   Password check enabled                 switch 2          open

      Password check disabled                switch 2         closed

  »   Factory configured - do not alter      switch 3          open

  »   Factory configured - do not alter      switch 4          open

  »   Factory configured - do not alter      switch 5         closed

  »   Factory configured - do not alter      switch 6         closed

  »   Monitor type select PS/2 style         switch 7         closed

      Monitor type select AT style           switch 7          open

  »   Monitor type select VGA or             switch 8          open
      fixed-frequency

      Monitor type select                    switch 8         closed
      multi-frequency

[Image]

                        USER CONFIGURABLE SETTINGS

                Function                     Jumper          Position

  »   Parity check enabled                     E1             closed

      Parity check disabled                    E1              open

  »   Factory configured - do not alter        E2             closed

  Note:AST CPU/Memory module part number is 202436-001.

                            DRAM CONFIGURATION

          Size                    Bank 0                   Bank 1

           2MB                  (2) 1M x 9                  NONE

           4MB                  (2) 1M x 9               (2) 1M x 9

           8MB                  (2) 4M x 9                  NONE

          10MB                  (2) 1M x 9               (2) 4M x 9

          16MB                  (2) 4M x 9               (2) 4M x 9

  Notes:128KB of DRAM is reserved for System and VGA BIOS shadowing and
  cannot be disabled.

  Up to two of the following memory boards may be installed in addition
  to the CPU/Memory

  module: AST part numbers 202275-004, 202275-006, 202387-001, or
  202387-005.