UNIDENTIFIED

486SX/DX/DX2-MAINBOARD

Processor              80486SX/80486DX/80486DX2
Processor Speed        20/25/33/50(internal)/50/66(internal)MHz
Chip Set               UNI
Video Chip Set         None
Maximum Onboard Memory 32MB
Maximum Video Memory   None
Cache                  64/128/256KB
BIOS                   AMI
Dimensions             260mm x 220mm
I/O Options            32-bit VESA local bus slots (3)
NPU Options            None

[Image]

                                CONNECTIONS

  Purpose                  Location    Purpose                  Location

  Turbo switch                H1       Reset switch                H5

  Turbo LED                   H2       External battery            J1

  Power LED & keylock         H3       32-bit VESA local bus   SL1 - SL3
                                       slots

  Speaker                     H4

                        USER CONFIGURABLE SETTINGS

                Function                     Label           Position

  »   Turbo enabled                            H1             Closed

      Turbo enabled through keyboard           H1              Open
      (CTRL, ALT, +)

      Turbo disabled through keyboard          H1              Open
      (CTRL, ALT, -)

  »   CMOS memory normal operation             J1           Pins 2 & 3
                                                              closed

      CMOS memory clear                        J1           Pins 3 & 4
                                                              closed

      Battery type select external             J1             Closed

  »   Monitor type select color                J3             Closed

      Monitor type select monochrome           J3              Open

  »   VL-BUS clock normal operation           JP43          Pins 2 & 3
                                                              closed

      VL-BUS clock adjusted                   JP43          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) 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

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

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

                    CACHE CONFIGURATION

     Size          Bank 0         Bank 1          TAG

     64KB        (4) 8K x 8     (4) 8K x 8    (1) 8K x 8

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

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

                        CACHE JUMPER CONFIGURATION

    Size          JP6            JP7            JP8             JP9

    64KB          Open         Closed          Open          Pins 1 & 2
                                                              closed

    128KB         Open         Closed         Closed      Pins 1 & 2, 3 &
                                                             4 closed

    256KB        Closed        Closed         Closed      Pins 1 & 2, 4 &
                                                             5 closed

           CPU SPEED SELECTION

  Speed      JP29      JP30      JP31

  20MHz      Open     Closed     Open

  25MHz     Closed     Open     Closed

  33MHz     Closed    Closed     Open

  50iMHz    Closed     Open     Closed

  50MHz      Open     Closed     Open

  66iMHz    Closed    Closed     Open

                          CPU TYPE SELECTION

               Type                               JP4

              80486SX                      Pins 5 & 6 closed

              80486DX               Pins 1 & 2, 4 & 5, 6 & 7 closed

             80486DX2               Pins 1 & 2, 4 & 5, 6 & 7 closed

                        VL BUS WAIT STATE SELECTION

               Setting                                JP20

                     0                                Open

  »                  1                               Closed

                          VL BUS SPEED SELECTION

                 Speed                                 JP19

                  <= 33MHz                             Open

  »               >33 MHz                             Closed