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       # SCI SYSTEMS, INC.
       
          SCI 486SX/DX SYSTEM BOARD
       
          Processor    80486SX/80486DX                                   
          Processor    25/33MHz                                          
          Speed        
          Chip Set     OPTI                                              
          Max. Onboard 64MB                                              
          DRAM         
          Cache        64/256KB                                          
          BIOS         Unidentified                                      
          Dimensions   330mm x 218mm                                     
          I/O Options  Floppy drive interface, IDE interface, parallel   
                       port, PS/2 mouse port, serial ports (2), VGA port 
          NPU Options  None                                              
       
   IMG IMG 1
          
       
          +------------------------------------------------------------+
          |                        CONNECTIONS                         |
          |------------------------------------------------------------|
          | Purpose              | Location | Purpose       | Location |
          |----------------------+----------+---------------+----------|
          | PS/2 mouse port      |    J1    | IDE interface |   J23    |
          |                      |          | LED           |          |
          |----------------------+----------+---------------+----------|
          | IDE interface        |    J5    | Reset switch  |   J24    |
          |----------------------+----------+---------------+----------|
          | Floppy drive         |    J6    | Speaker       |   J25    |
          | interface            |          |               |          |
          |----------------------+----------+---------------+----------|
          | Parallel port        |    J8    | Power LED &   |   J26    |
          |                      |          | keylock       |          |
          |----------------------+----------+---------------+----------|
          | Serial port 2        |    J9    | VGA port      |   J27    |
          |----------------------+----------+---------------+----------|
          | Serial port 1        |   J10    |               |          |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 USER CONFIGURABLE SETTINGS                 |
          |------------------------------------------------------------|
          |           Function            | Jumper/Switch |  Position  |
          |-------------------------------+---------------+------------|
          | » | Monitor type select color |      W1       | pins 1 & 2 |
          |   |                           |               |   closed   |
          |---+---------------------------+---------------+------------|
          |   | Monitor type select       |      W1       | pins 2 & 3 |
          |   | monochrome                |               |   closed   |
          |---+---------------------------+---------------+------------|
          | » | CMOS memory normal        |      W2       | pins 1 & 2 |
          |   | operation                 |               |   closed   |
          |---+---------------------------+---------------+------------|
          |   | CMOS memory clear         |      W2       | pins 2 & 3 |
          |   |                           |               |   closed   |
          |---+---------------------------+---------------+------------|
          | » | SYSCLK enabled            |      W3       | pins 2 & 3 |
          |   |                           |               |   closed   |
          |---+---------------------------+---------------+------------|
          |   | SYSCLK/2 enabled          |      W3       | pins 1 & 2 |
          |   |                           |               |   closed   |
          |---+---------------------------+---------------+------------|
          | » | On board VGA enabled      |      W10      | pins 1 & 2 |
          |   |                           |               |   closed   |
          |---+---------------------------+---------------+------------|
          |   | On board VGA disabled     |      W10      | pins 2 & 3 |
          |   |                           |               |   closed   |
          |---+---------------------------+---------------+------------|
          | » | Video horizontal scan     |     SW1/5     |     On     |
          |   | rate select 31.5 kHz      |               |            |
          |---+---------------------------+---------------+------------|
          |   | Video horizontal scan     |     SW1/5     |    Off     |
          |   | rate select 40kHz         |               |            |
          |---+---------------------------+---------------+------------|
          | » | Video memory select 512KB |     SW1/6     |     On     |
          |---+---------------------------+---------------+------------|
          |   | Video memory select 1MB   |     SW1/6     |    Off     |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                     DRAM CONFIGURATION                     |
          |------------------------------------------------------------|
          | Size |   Bank 0    |   Bank 1    |   Bank 2   |   Bank 3   |
          |------+-------------+-------------+------------+------------|
          | 1MB  | (1) 256K x  |    NONE     |    NONE    |    NONE    |
          |      |     36      |             |            |            |
          |------+-------------+-------------+------------+------------|
          | 2MB  | (1) 256K x  | (1) 256K x  |    NONE    |    NONE    |
          |      |     36      |     36      |            |            |
          |------+-------------+-------------+------------+------------|
          | 4MB  | (1) 1M x 36 |    NONE     |    NONE    |    NONE    |
          |------+-------------+-------------+------------+------------|
          | 5MB  | (1) 256K x  | (1) 1M x 36 |    NONE    |    NONE    |
          |      |     36      |             |            |            |
          |------+-------------+-------------+------------+------------|
          | 6MB  | (1) 256K x  | (1) 256K x  |  (1) 1M x  |    NONE    |
          |      |     36      |     36      |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 8MB  | (1) 1M x 36 | (1) 1M x 36 |    NONE    |    NONE    |
          |------+-------------+-------------+------------+------------|
          | 9MB  | (1) 256K x  | (1) 1M x 36 |  (1) 1M x  |    NONE    |
          |      |     36      |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 10MB | (1) 256K x  | (1) 256K x  |  (1) 1M x  |  (1) 1M x  |
          |      |     36      |     36      |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 12MB | (1) 1M x 36 | (1) 1M x 36 |  (1) 1M x  |    NONE    |
          |      |             |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 13MB | (1) 256K x  | (1) 1M x 36 |  (1) 1M x  |  (1) 1M x  |
          |      |     36      |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 16MB | (1) 1M x 36 | (1) 1M x 36 |  (1) 1M x  |  (1) 1M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 16MB | (1) 4M x 36 |    NONE     |    NONE    |    NONE    |
          |------+-------------+-------------+------------+------------|
          | 20MB | (1) 1M x 36 | (1) 4M x 36 |    NONE    |    NONE    |
          |------+-------------+-------------+------------+------------|
          | 20MB | (1) 4M x 36 | (1) 1M x 36 |    NONE    |    NONE    |
          |------+-------------+-------------+------------+------------|
          | 24MB | (1) 1M x 36 | (1) 1M x 36 |  (1) 4M x  |    NONE    |
          |      |             |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 24MB | (1) 1M x 36 | (1) 4M x 36 |  (1) 1M x  |    NONE    |
          |      |             |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 24MB | (1) 4M x 36 | (1) 1M x 36 |  (1) 1M x  |    NONE    |
          |      |             |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 28MB | (1) 1M x 36 | (1) 1M x 36 |  (1) 4M x  |  (1) 1M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 28MB | (1) 1M x 36 | (1) 4M x 36 |  (1) 1M x  |  (1) 1M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 28MB | (1) 4M x 36 | (1) 1M x 36 |  (1) 1M x  |  (1) 1M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 32MB | (1) 4M x 36 | (1) 4M x 36 |    NONE    |    NONE    |
          |------+-------------+-------------+------------+------------|
          | 36MB | (1) 1M x 36 | (1) 1M x 36 |  (1) 1M x  |    NONE    |
          |      |             |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 36MB | (1) 1M x 36 | (1) 1M x 36 |  (1) 1M x  |    NONE    |
          |      |             |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 36MB | (1) 4M x 36 | (1) 4M x 36 |  (1) 1M x  |    NONE    |
          |      |             |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 40MB | (1) 1M x 36 | (1) 1M x 36 |  (1) 4M x  |  (1) 4M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 40MB | (1) 1M x 36 | (1) 4M x 36 |  (1) 4M x  |  (1) 1M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 40MB | (1) 4M x 36 | (1) 1M x 36 |  (1) 4M x  |  (1) 1M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 40MB | (1) 4M x 36 | (1) 4M x 36 |  (1) 1M x  |  (1) 1M x  |
          |      |             |             |     36     |     36     |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 DRAM CONFIGURATION (CON’T)                 |
          |------------------------------------------------------------|
          | Size |   Bank 0    |   Bank 1    |   Bank 2   |   Bank 3   |
          |------+-------------+-------------+------------+------------|
          | 48MB | (1) 4M x 36 | (1) 4M x 36 |  (1) 4M x  |    NONE    |
          |      |             |             |     36     |            |
          |------+-------------+-------------+------------+------------|
          | 52MB | (1) 1M x 36 | (1) 4M x 36 |  (1) 4M x  |  (1) 4M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 52MB | (1) 4M x 36 | (1) 1M x 36 |  (1) 4M x  |  (1) 4M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 52MB | (1) 4M x 36 | (1) 4M x 36 |  (1) 4M x  |  (1) 1M x  |
          |      |             |             |     36     |     36     |
          |------+-------------+-------------+------------+------------|
          | 64MB | (1) 4M x 36 | (1) 4M x 36 |  (1) 4M x  |  (1) 4M x  |
          |      |             |             |     36     |     36     |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                    CACHE CONFIGURATION                     |
          |------------------------------------------------------------|
          |    Size    |    Bank 0     |    Bank 1     |      TAG      |
          |------------+---------------+---------------+---------------|
          |    64KB    |  (4) 8K x 8   |  (4) 8K x 8   |  (2) 16K x 4  |
          |------------+---------------+---------------+---------------|
          |   256KB    |  (4) 32K x 8  |  (4) 32K x 8  |  (2) 16K x 4  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 CACHE JUMPER CONFIGURATION                 |
          |------------------------------------------------------------|
          | Size  |     W4      |     W5     |     W9     |    W11     |
          |-------+-------------+------------+------------+------------|
          | 64KB  | pins 2 & 3  | pins 2 & 3 | pins 2 & 3 | pins 2 & 3 |
          |       |   closed    |   closed   |   closed   |   closed   |
          |-------+-------------+------------+------------+------------|
          | 256KB | pins 1 & 2  | pins 1 & 2 | pins 1 & 2 | pins 2 & 3 |
          |       |   closed    |   closed   |   closed   |   closed   |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   CPU TYPE CONFIGURATION                   |
          |------------------------------------------------------------|
          | Type  |       W6        |       W7        |       W8       |
          |-------+-----------------+-----------------+----------------|
          | 486SX |   pins 2 & 3    |   pins 2 & 3    |      N/A       |
          |       |     closed      |     closed      |                |
          |-------+-----------------+-----------------+----------------|
          | 487SX |   pins 1 & 2    |   pins 1 & 2    |   pins 1 & 2   |
          |       |     closed      |     closed      |     closed     |
          |-------+-----------------+-----------------+----------------|
          | 486DX |   pins 1 & 2    |   pins 1 & 2    |   pins 2 & 3   |
          |       |     closed      |     closed      |     closed     |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |              VIDEO CONFIGURATION (800 X 600)               |
          |------------------------------------------------------------|
          |      Refresh rate       |      SW1/1      |     SW1/2      |
          |-------------------------+-----------------+----------------|
          | »    |       60Hz       |       Off       |       On       |
          |------+------------------+-----------------+----------------|
          |      |       56Hz       |       Off       |      Off       |
          |------+------------------+-----------------+----------------|
          |      |       56Hz       |       On        |       On       |
          |------+------------------+-----------------+----------------|
          |      |       72Hz       |       On        |      Off       |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |              VIDEO CONFIGURATION (1024 X 768)              |
          |------------------------------------------------------------|
          |      Refresh rate       |      SW1/3      |     SW1/4      |
          |-------------------------+-----------------+----------------|
          | »  |     Interlaced     |       Off       |      Off       |
          |----+--------------------+-----------------+----------------|
          |    |        60Hz        |       Off       |       On       |
          |----+--------------------+-----------------+----------------|
          |    |        70Hz        |       On        |      Off       |
          |----+--------------------+-----------------+----------------|
          |    |        72Hz        |       On        |       On       |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 VIDEO MEMORY CONFIGURATION                 |
          |------------------------------------------------------------|
          |     Size      |        Bank 0        |       Bank 1        |
          |---------------+----------------------+---------------------|
          |     512KB     |     (4) 256K x 4     |        NONE         |
          |---------------+----------------------+---------------------|
          |      1MB      |     (4) 256K x 4     |    (4) 256K x 4     |
          |------------------------------------------------------------|
          | Note: Bank 0 is factory installed and is not configurable. |
          +------------------------------------------------------------+