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       # UNIDENTIFIED
       
          50/33/25/20MHZ MAINBOARD
       
          Processor         80486SX/80487SX/80486DX/80486DX2             
          Processor Speed   20/25/33/40/50 (Internal) /50/66 (Internal)  
          Chip Set          C & T                                        
          Max. onboard DRAM 32MB                                         
          Cache             64/128/256KB                                 
          BIOS              AMI                                          
          Dimensions        330mm x 218mm                                
          I/O Options       None                                         
          NPU Options       None                                         
       
   IMG IMG 1
          
       
          +------------------------------------------------------------+
          |                        CONNECTIONS                         |
          |------------------------------------------------------------|
          | Purpose           | Location | Purpose          | Location |
          |-------------------+----------+------------------+----------|
          | Power LED &       |   J17    | External battery |   J20    |
          | keylock           |          |                  |          |
          |-------------------+----------+------------------+----------|
          | Speaker           |   J18    | Turbo switch     |   J21    |
          |-------------------+----------+------------------+----------|
          | Reset switch      |   J19    | Turbo LED        |   J22    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 USER CONFIGURABLE SETTINGS                 |
          |------------------------------------------------------------|
          |           Function            | Jumper/Switch |  Position  |
          |-------------------------------+---------------+------------|
          | » | Monitor type select       |      JP3      |    Open    |
          |   | monochrome                |               |            |
          |---+---------------------------+---------------+------------|
          |   | Monitor type select color |      JP3      |   Closed   |
          |---+---------------------------+---------------+------------|
          | » | CMOS memory normal        |      JP5      | Pins 1 & 2 |
          |   | operation                 |               |   closed   |
          |---+---------------------------+---------------+------------|
          |   | CMOS memory clear         |      JP5      | Pins 2 & 3 |
          |   |                           |               |   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     |
          |------------------+--------------------+--------------------|
          |       32MB       |     (4) 4M x 9     |     (4) 4M x 9     |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                    CACHE CONFIGURATION                     |
          |------------------------------------------------------------|
          | Size  |     Max     |   Bank 0   |   Bank 1   |    TAG     |
          |       |  Cachable   |            |            |            |
          |-------+-------------+------------+------------+------------|
          | 64KB  |    16MB     | (4) 8K x 8 | (4) 8K x 8 | (1) 8K x 8 |
          |-------+-------------+------------+------------+------------|
          | 128KB |    32MB     | (4) 32K x  |    NONE    | (1) 8K x 8 |
          |       |             |     8      |            |            |
          |-------+-------------+------------+------------+------------|
          | 256KB |    64MB     | (4) 32K x  | (4) 32K x  | (1) 32K x  |
          |       |             |     8      |     8      |     8      |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 CACHE JUMPER CONFIGURATION                 |
          |------------------------------------------------------------|
          |       Size       |        JP24        |        JP25        |
          |------------------+--------------------+--------------------|
          |       64KB       |        Open        |        Open        |
          |------------------+--------------------+--------------------|
          |      128KB       | Pins 1 & 2 closed  | Pins 1 & 2 closed  |
          |------------------+--------------------+--------------------|
          |      256KB       | Pins 2 & 3 closed  | Pins 2 & 3 closed  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                  CPU SPEED CONFIGURATION                   |
          |------------------------------------------------------------|
          |           Speed            |             JP21              |
          |----------------------------+-------------------------------|
          |       80486SX/20MHz        |       Pins 5 & 6 closed       |
          |----------------------------+-------------------------------|
          |       80486SX/25MHz        |   Pins 1 & 2, 5 & 6 closed    |
          |----------------------------+-------------------------------|
          |       80486SX/33MHz        |   Pins 1 & 2, 3 & 4 closed    |
          |----------------------------+-------------------------------|
          |       80487SX/20MHz        |       Pins 5 & 6 closed       |
          |----------------------------+-------------------------------|
          |       80486DX/25MHz        |   Pins 1 & 2, 5 & 6 closed    |
          |----------------------------+-------------------------------|
          |       80486DX/33MHz        |   Pins 1 & 2, 3 & 4 closed    |
          |----------------------------+-------------------------------|
          |       80486DX/40MHz        |       Pins 5 & 6 closed       |
          |----------------------------+-------------------------------|
          |       80486DX/50MHz        |       Pins 3 & 4 closed       |
          |----------------------------+-------------------------------|
          |      80486DX2/50i MHz      |   Pins 1 & 2, 5 & 6 closed    |
          |----------------------------+-------------------------------|
          |      80486DX2/66i MHz      |   Pins 1 & 2, 3 & 4 closed    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   CPU TYPE CONFIGURATION                   |
          |------------------------------------------------------------|
          |     TYPE      |    JP9    |  JP11  |   JP12    |   JP13    |
          |---------------+-----------+--------+-----------+-----------|
          | 80486SX/20MHz | Pins 2 &  |  Open  | Pins 2 &  | Pins 2 &  |
          |               | 3 closed  |        | 3 closed  | 3 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80486SX/25MHz | Pins 1 &  |  Open  | Pins 2 &  | Pins 2 &  |
          |               | 2 closed  |        | 3 closed  | 3 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80486SX/33MHz | Pins 1 &  |  Open  | Pins 2 &  | Pins 2 &  |
          |               | 2 closed  |        | 3 closed  | 3 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80487SX/20MHz | Pins 2 &  | Closed | Pins 2 &  | Pins 1 &  |
          |               | 3 closed  |        | 3 closed  | 2 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80486DX/25MHz | Pins 1 &  | Closed | Pins 1 &  | Pins 1 &  |
          |               | 2 closed  |        | 2 closed  | 2 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80486DX/33MHz | Pins 1 &  | Closed | Pins 1 &  | Pins 1 &  |
          |               | 2 closed  |        | 2 closed  | 2 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80486DX/40MHz | Pins 1 &  | Closed | Pins 1 &  | Pins 1 &  |
          |               | 2 closed  |        | 2 closed  | 2 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80486DX/50MHz | Pins 1 &  | Closed | Pins 1 &  | Pins 1 &  |
          |               | 2 closed  |        | 2 closed  | 2 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80486DX2/50i  | Pins 1 &  | Closed | Pins 1 &  | Pins 1 &  |
          |      MHz      | 2 closed  |        | 2 closed  | 2 closed  |
          |---------------+-----------+--------+-----------+-----------|
          | 80486DX2/66i  | Pins 1 &  | Closed | Pins 1 &  | Pins 1 &  |
          |      MHz      | 2 closed  |        | 2 closed  | 2 closed  |
          +------------------------------------------------------------+