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       # SILICON STAR INTERNATIONAL, INC.
       
          AH4/AH4T (REV. 1.2)
       
       Processor  80486SX/SL80486SX/CX486M7/80486DX/SL80486DX/CX486DX2/AM486DX2/80486DX2/SL80486DX2/AM486DX4/80486DX4 
       Processor  20/25/33/40/50(internal)/66(internal)/75(internal)/100(internal)MHz                                 
       Speed      
       Chip Set   Unidentifed                                                                                         
       Max.       128MB                                                                                               
       Onboard    
       DRAM       
       Cache      128/256/512KB                                                                                       
       BIOS       Award                                                                                               
       Dimensions 330mm x 218mm                                                                                       
       I/O        32-bit VESA local bus slots (3), green PC connector                                                 
       Options    
       NPU        None                                                                                                
       Options    
       
   IMG IMG 1
          
       
          +------------------------------------------------------------+
          |                        CONNECTIONS                         |
          |------------------------------------------------------------|
          | Purpose            | Location | Purpose         | Location |
          |--------------------+----------+-----------------+----------|
          | External battery   |    J1    | Reset switch    |   JW3    |
          |--------------------+----------+-----------------+----------|
          | Green PC connector |   JP45   | Turbo LED       |   JW4    |
          |                    | pins 7 - |                 |          |
          |                    |    8     |                 |          |
          |--------------------+----------+-----------------+----------|
          | Power LED &        |   JW1    | Turbo switch    |   JW5    |
          | keylock            |          |                 |          |
          |--------------------+----------+-----------------+----------|
          | Speaker            |   JW2    | 32-bit VESA     |  SL1 -   |
          |                    |          | local bus slots |   SL3    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 USER CONFIGURABLE SETTINGS                 |
          |------------------------------------------------------------|
          |               Function               | Jumper |  Position  |
          |--------------------------------------+--------+------------|
          | »  | CMOS memory normal operation    |  JP16  | pins 1 & 2 |
          |    |                                 |        |   closed   |
          |----+---------------------------------+--------+------------|
          |    | CMOS memory clear               |  JP16  | pins 2 & 3 |
          |    |                                 |        |   closed   |
          |----+---------------------------------+--------+------------|
          | »  | Factory configured - do not     |  JP17  |    N/A     |
          |    | alter                           |        |            |
          |----+---------------------------------+--------+------------|
          | »  | Factory configured - do not     |  JP19  | pins 1 & 2 |
          |    | alter                           |        |   closed   |
          |----+---------------------------------+--------+------------|
          | »  | Factory configured - do not     |  JP23  | pins 1 & 2 |
          |    | alter                           |        |   closed   |
          |----+---------------------------------+--------+------------|
          | »  | Factory configured - do not     |  JP26  |    Open    |
          |    | alter                           |        |            |
          |----+---------------------------------+--------+------------|
          | »  | Factory configured - do not     |  JP30  |    N/A     |
          |    | alter                           |        |            |
          |----+---------------------------------+--------+------------|
          | »  | Factory configured - do not     |  JP31  |    N/A     |
          |    | alter                           |        |            |
          |----+---------------------------------+--------+------------|
          | »  | Factory configured - do not     |  JP42  |   Closed   |
          |    | alter                           |        |            |
          |------------------------------------------------------------|
          | Note: The locations of JP19, JP23 & JP42 are unidentified. |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                     DRAM CONFIGURATION                     |
          |------------------------------------------------------------|
          | Size |    Bank 0     |   Bank 1    |   Bank 2   |  Bank 3  |
          |------+---------------+-------------+------------+----------|
          | 1MB  | (1) 256K x 36 |    NONE     |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 2MB  | (1) 256K x 36 | (1) 256K x  |    NONE    |   NONE   |
          |      |               |     36      |            |          |
          |------+---------------+-------------+------------+----------|
          | 2MB  | (1) 512K x 36 |    NONE     |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 4MB  | (1) 512K x 36 | (1) 512K x  |    NONE    |   NONE   |
          |      |               |     36      |            |          |
          |------+---------------+-------------+------------+----------|
          | 4MB  |  (1) 1M x 36  |    NONE     |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 4MB  | (1) 256K x 36 | (1) 256K x  | (1) 512K x |   NONE   |
          |      |               |     36      |     36     |          |
          |------+---------------+-------------+------------+----------|
          | 5MB  | (1) 256K x 36 | (1) 1M x 36 |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 6MB  | (1) 256K x 36 | (1) 256K x  |  (1) 1M x  |   NONE   |
          |      |               |     36      |     36     |          |
          |------+---------------+-------------+------------+----------|
          | 6MB  | (1) 512K x 36 | (1) 1M x 36 |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 8MB  | (1) 256K x 36 | (1) 256K x  | (1) 512K x | (1) 1M x |
          |      |               |     36      |     36     |    36    |
          |------+---------------+-------------+------------+----------|
          | 8MB  | (1) 512K x 36 | (1) 512K x  |  (1) 1M x  |   NONE   |
          |      |               |     36      |     36     |          |
          |------+---------------+-------------+------------+----------|
          | 8MB  |  (1) 1M x 36  | (1) 1M x 36 |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 8MB  |  (1) 2M x 36  |    NONE     |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 10MB | (1) 256K x 36 | (1) 256K x  |  (1) 1M x  | (1) 1M x |
          |      |               |     36      |     36     |    36    |
          |------+---------------+-------------+------------+----------|
          | 12MB | (1) 512K x 36 | (1) 512K x  |  (1) 1M x  | (1) 1M x |
          |      |               |     36      |     36     |    36    |
          |------+---------------+-------------+------------+----------|
          | 12MB |  (1) 1M x 36  | (1) 1M x 36 |  (1) 1M x  |   NONE   |
          |      |               |             |     36     |          |
          |------+---------------+-------------+------------+----------|
          | 16MB |  (1) 2M x 36  | (1) 2M x 36 |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 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   |
          |------+---------------+-------------+------------+----------|
          | 17MB | (1) 256K x 36 | (1) 4M x 36 |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 18MB | (1) 256K x 36 | (1) 256K x  |  (1) 4M x  |   NONE   |
          |      |               |     36      |     36     |          |
          |------+---------------+-------------+------------+----------|
          | 20MB | (1) 512K x 36 | (1) 512K x  |  (1) 4M x  |   NONE   |
          |      |               |     36      |     36     |          |
          |------+---------------+-------------+------------+----------|
          | 20MB |  (1) 1M x 36  | (1) 4M x 36 |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 24MB |  (1) 2M x 36  | (1) 2M x 36 |  (1) 2M x  |   NONE   |
          |      |               |             |     36     |          |
          |------+---------------+-------------+------------+----------|
          | 24MB | (1) 512K x 36 | (1) 512K x  |  (1) 1M x  | (1) 4M x |
          |      |               |     36      |     36     |    36    |
          |------+---------------+-------------+------------+----------|
          | 24MB |  (1) 1M x 36  | (1) 1M x 36 |  (1) 4M x  |   NONE   |
          |      |               |             |     36     |          |
          |------+---------------+-------------+------------+----------|
          | 32MB |  (1) 2M x 36  | (1) 2M x 36 |  (1) 2M x  | (1) 2M x |
          |      |               |             |     36     |    36    |
          |------+---------------+-------------+------------+----------|
          | 32MB |  (1) 4M x 36  | (1) 4M x 36 |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 32MB |  (1) 8M x 36  |    NONE     |    NONE    |   NONE   |
          |------+---------------+-------------+------------+----------|
          | 36MB | (1) 512K x 36 | (1) 512K x  |  (1) 4M x  | (1) 4M x |
          |      |               |     36      |     36     |    36    |
          |------+---------------+-------------+------------+----------|
          | 36MB |  (1) 1M x 36  | (1) 4M x 36 |  (1) 4M x  |   NONE   |
          |      |               |             |     36     |          |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 DRAM CONFIGURATION (CON’T)                 |
          |------------------------------------------------------------|
          | Size  |   Bank 0    |   Bank 1   |   Bank 2   |   Bank 3   |
          |-------+-------------+------------+------------+------------|
          | 36MB  | (1) 1M x 36 |  (1) 8M x  |    NONE    |    NONE    |
          |       |             |     36     |            |            |
          |-------+-------------+------------+------------+------------|
          | 40MB  | (1) 1M x 36 |  (1) 1M x  |  (1) 4M x  |  (1) 4M x  |
          |       |             |     36     |     36     |     36     |
          |-------+-------------+------------+------------+------------|
          | 40MB  | (1) 1M x 36 |  (1) 1M x  |  (1) 8M x  |    NONE    |
          |       |             |     36     |     36     |            |
          |-------+-------------+------------+------------+------------|
          | 48MB  | (1) 4M x 36 |  (1) 4M x  |  (1) 4M x  |    NONE    |
          |       |             |     36     |     36     |            |
          |-------+-------------+------------+------------+------------|
          | 48MB  | (1) 4M x 36 |  (1) 8M x  |    NONE    |    NONE    |
          |       |             |     36     |            |            |
          |-------+-------------+------------+------------+------------|
          | 64MB  | (1) 4M x 36 |  (1) 4M x  |  (1) 4M x  |  (1) 4M x  |
          |       |             |     36     |     36     |     36     |
          |-------+-------------+------------+------------+------------|
          | 64MB  |  (1) 16M x  |    NONE    |    NONE    |    NONE    |
          |       |     36      |            |            |            |
          |-------+-------------+------------+------------+------------|
          | 64MB  | (1) 4M x 36 |  (1) 4M x  |  (1) 8M x  |    NONE    |
          |       |             |     36     |     36     |            |
          |-------+-------------+------------+------------+------------|
          | 64MB  | (1) 8M x 36 |  (1) 8M x  |    NONE    |    NONE    |
          |       |             |     36     |            |            |
          |-------+-------------+------------+------------+------------|
          | 65MB  | (1) 256K x  | (1) 16M x  |    NONE    |    NONE    |
          |       |     36      |     36     |            |            |
          |-------+-------------+------------+------------+------------|
          | 68MB  | (1) 1M x 36 | (1) 16M x  |    NONE    |    NONE    |
          |       |             |     36     |            |            |
          |-------+-------------+------------+------------+------------|
          | 68MB  | (1) 1M x 36 |  (1) 8M x  |  (1) 8M x  |    NONE    |
          |       |             |     36     |     36     |            |
          |-------+-------------+------------+------------+------------|
          | 72MB  | (1) 1M x 36 |  (1) 1M x  | (1) 16M x  |    NONE    |
          |       |             |     36     |     36     |            |
          |-------+-------------+------------+------------+------------|
          | 72MB  | (1) 1M x 36 |  (1) 1M x  |  (1) 8M x  |  (1) 8M x  |
          |       |             |     36     |     36     |     36     |
          |-------+-------------+------------+------------+------------|
          | 80MB  | (1) 4M x 36 | (1) 16M x  |    NONE    |    NONE    |
          |       |             |     36     |            |            |
          |-------+-------------+------------+------------+------------|
          | 80MB  | (1) 4M x 36 |  (1) 8M x  |  (1) 8M x  |    NONE    |
          |       |             |     36     |     36     |            |
          |-------+-------------+------------+------------+------------|
          | 96MB  | (1) 4M x 36 |  (1) 4M x  | (1) 16M x  |    NONE    |
          |       |             |     36     |     36     |            |
          |-------+-------------+------------+------------+------------|
          | 96MB  | (1) 4M x 36 |  (1) 4M x  |  (1) 8M x  |  (1) 8M x  |
          |       |             |     36     |     36     |     36     |
          |-------+-------------+------------+------------+------------|
          | 96MB  | (1) 8M x 36 |  (1) 8M x  |  (1) 8M x  |    NONE    |
          |       |             |     36     |     36     |            |
          |-------+-------------+------------+------------+------------|
          | 128MB |  (1) 16M x  | (1) 16M x  |    NONE    |    NONE    |
          |       |     36      |     36     |            |            |
          |-------+-------------+------------+------------+------------|
          | 128MB | (1) 8M x 36 |  (1) 8M x  |  (1) 8M x  |  (1) 8M x  |
          |       |             |     36     |     36     |     36     |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                    CACHE CONFIGURATION                     |
          |------------------------------------------------------------|
          |    Size    |    Bank 0     |    Bank 1     |      TAG      |
          |------------+---------------+---------------+---------------|
          |   128KB    |  (4) 32K x 8  |     NONE      |  (1) 8K x 8   |
          |------------+---------------+---------------+---------------|
          |   256KB    |  (4) 32K x 8  |  (4) 32K x 8  |  (1) 32K x 8  |
          |------------+---------------+---------------+---------------|
          |   256KB    |  (4) 64K x 8  |     NONE      |  (1) 32K x 8  |
          |------------+---------------+---------------+---------------|
          |   512KB    |  (4) 64K x 8  |  (4) 64K x 8  |  (1) 32K x 8  |
          |------------+---------------+---------------+---------------|
          |   512KB    | (4) 128K x 8  |     NONE      |  (1) 32K x 8  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 CACHE JUMPER CONFIGURATION                 |
          |------------------------------------------------------------|
          |   Size   |   JP1    |   JP2    |   JP4   |  JP40  |  JP41  |
          |----------+----------+----------+---------+--------+--------|
          |  128KB   |  1 & 2   |  1 & 2   |  1 & 2  | 1 & 2  | 1 & 2  |
          |----------+----------+----------+---------+--------+--------|
          |  256KB   |  2 & 3   |  2 & 3   |  1 & 2  | 2 & 3  | 2 & 3  |
          |----------+----------+----------+---------+--------+--------|
          |  256KB   |  1 & 2   |  2 & 3   |  1 & 2  | 1 & 2  | 1 & 2  |
          |----------+----------+----------+---------+--------+--------|
          |  512KB   |  2 & 3   |  2 & 3   |  2 & 3  | 2 & 3  | 2 & 3  |
          |----------+----------+----------+---------+--------+--------|
          |  512KB   |  1 & 2   |  2 & 3   |  2 & 3  | 1 & 2  | 1 & 2  |
          |------------------------------------------------------------|
          | Note: Pins designated should be in the closed position.    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   CPU TYPE CONFIGURATION                   |
          |------------------------------------------------------------|
          |    Type     |   JP8   |   JP9   |  JP11  |  JP12  |  JP14  |
          |-------------+---------+---------+--------+--------+--------|
          |   80486SX   |  2 & 3  |  Open   |  Open  | 3 & 4  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |  SL80486SX  |  2 & 3  |  Open   |  Open  | 3 & 4  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |   CX486M7   |  1 & 2  | Closed  | 2 & 3  | 2 & 3  | 1 & 2, |
          |             |         |         |        |        | 3 & 4  |
          |-------------+---------+---------+--------+--------+--------|
          |   80486DX   |  1 & 2  | Closed  | 2 & 3  | 3 & 4  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |  SL80486DX  |  1 & 2  | Closed  | 2 & 3  | 3 & 4  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |  CX486DX2   |  1 & 2  | Closed  | 2 & 3  | 2 & 3  | 1 & 2, |
          |             |         |         |        |        | 3 & 4  |
          |-------------+---------+---------+--------+--------+--------|
          |  AM486DX2   |  1 & 2  | Closed  | 2 & 3  | 3 & 4  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |  80486DX2   |  1 & 2  | Closed  | 2 & 3  | 3 & 4  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          | SL80486DX2  |  1 & 2  | Closed  | 2 & 3  | 3 & 4  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |  AM486DX4   |  1 & 2  | Closed  | 2 & 3  | 3 & 4  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |  80486DX4   |  1 & 2  | Closed  | 2 & 3  | 3 & 4  | 2 & 3  |
          |------------------------------------------------------------|
          |      Note: Pins designated should be in the closed         |
          |      position. SL80486DX/DX2 is only available on the AH4T |
          |      mainboard                                             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   CPU TYPE CONFIGURATION                   |
          |------------------------------------------------------------|
          |    Type     |  JP15   |  JP21   |  JP22  |  JP24  |  JP25  |
          |-------------+---------+---------+--------+--------+--------|
          |   80486SX   |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |-------------+---------+---------+--------+--------+--------|
          |  SL80486SX  |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |-------------+---------+---------+--------+--------+--------|
          |   CX486M7   |  2 & 3  |  1 & 2  | 2 & 3  | 2 & 3  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |   80486DX   |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |-------------+---------+---------+--------+--------+--------|
          |  SL80486DX  |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |-------------+---------+---------+--------+--------+--------|
          |  CX486DX2   |  2 & 3  |  1 & 2  | 2 & 3  | 2 & 3  | 2 & 3  |
          |-------------+---------+---------+--------+--------+--------|
          |  AM486DX2   |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |-------------+---------+---------+--------+--------+--------|
          |  80486DX2   |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |-------------+---------+---------+--------+--------+--------|
          | SL80486DX2  |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |-------------+---------+---------+--------+--------+--------|
          |  AM486DX4   |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |-------------+---------+---------+--------+--------+--------|
          |  80486DX4   |  4 & 5  |  2 & 3  | 1 & 2  |  Open  |  Open  |
          |------------------------------------------------------------|
          |      Note: Pins designated should be in the closed         |
          |      position. SL80486DX/DX2 is only available on the AH4T |
          |      mainboard                                             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   CPU TYPE CONFIGURATION                   |
          |------------------------------------------------------------|
          |    Type    | JP32  | JP46  | JP48  | JP49  | JP50 |  JP62  |
          |------------+-------+-------+-------+-------+------+--------|
          |  80486SX   | 1 & 2 | 2 & 3 | 2 & 3 | Open  | 2 &  |  Open  |
          |            |       |       |       |       |  3   |        |
          |------------+-------+-------+-------+-------+------+--------|
          | SL80486SX  | 1 & 2 | 2 & 3 | 2 & 3 | Open  | 2 &  |  Open  |
          |            |       |       |       |       |  3   |        |
          |------------+-------+-------+-------+-------+------+--------|
          |  CX486M7   | 1 & 2 | 1 & 2 | 2 & 3 | Open  | 2 &  |  Open  |
          |            |       |       |       |       |  3   |        |
          |------------+-------+-------+-------+-------+------+--------|
          |  80486DX   | 1 & 2 | 2 & 3 | 2 & 3 | Open  | 2 &  |  Open  |
          |            |       |       |       |       |  3   |        |
          |------------+-------+-------+-------+-------+------+--------|
          | SL80486DX  | 1 & 2 | 2 & 3 | 2 & 3 | Open  | 2 &  |  Open  |
          |            |       |       |       |       |  3   |        |
          |------------+-------+-------+-------+-------+------+--------|
          |  CX486DX2  | 1 & 2 | 1 & 2 | 1 & 2 | Open  | 1 &  |  Open  |
          |            |       |       |       |       |  2   |        |
          |------------+-------+-------+-------+-------+------+--------|
          |  AM486DX2  | 1 & 2 | 2 & 3 | 1 & 2 | Open  | 1 &  |  Open  |
          |            |       |       |       |       |  2   |        |
          |------------+-------+-------+-------+-------+------+--------|
          |  80486DX2  | 1 & 2 | 2 & 3 | 2 & 3 | Open  | 2 &  |  Open  |
          |            |       |       |       |       |  3   |        |
          |------------+-------+-------+-------+-------+------+--------|
          | SL80486DX2 | 1 & 2 | 2 & 3 | 2 & 3 | Open  | 2 &  |  Open  |
          |            |       |       |       |       |  3   |        |
          |------------+-------+-------+-------+-------+------+--------|
          |  AM486DX4  | 1 & 2 | 2 & 3 | 1 & 2 | 1 & 2 | 1 &  | Closed |
          |            |       |       |       |       |  2   |        |
          |------------+-------+-------+-------+-------+------+--------|
          |  80486DX4  | Open  | 2 & 3 | 1 & 2 | 1 & 2 | 1 &  |  Open  |
          |            |       |       |       |       |  2   |        |
          |------------------------------------------------------------|
          |      Note: Pins designated should be in the closed         |
          |      position. SL80486DX/DX2 is only available on the AH4T |
          |      mainboard                                             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                  CPU SPEED CONFIGURATION                   |
          |------------------------------------------------------------|
          |     Speed     |     JP5      |     JP6      |     JP7      |
          |---------------+--------------+--------------+--------------|
          |     20MHz     |    Closed    |     Open     |    Closed    |
          |---------------+--------------+--------------+--------------|
          |     25MHz     |    Closed    |    Closed    |     Open     |
          |---------------+--------------+--------------+--------------|
          |     33MHz     |     Open     |    Closed    |    Closed    |
          |---------------+--------------+--------------+--------------|
          |     40MHz     |    Closed    |     Open     |     Open     |
          |---------------+--------------+--------------+--------------|
          |    50iMHz     |    Closed    |    Closed    |     Open     |
          |---------------+--------------+--------------+--------------|
          |    66iMHz     |     Open     |    Closed    |    Closed    |
          |---------------+--------------+--------------+--------------|
          |    75iMHz     |    Closed    |    Closed    |     Open     |
          |---------------+--------------+--------------+--------------|
          |    100iMHz    |     Open     |    Closed    |    Closed    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                 CPU VOLTAGE CONFIGURATION                  |
          |------------------------------------------------------------|
          |  Voltage  |    JP53    |   JP54    |   JP55    |   JP56    |
          |-----------+------------+-----------+-----------+-----------|
          |   3.3v    |   Closed   |   Open    |   Open    |   Open    |
          |-----------+------------+-----------+-----------+-----------|
          |   3.45v   |    Open    |  Closed   |   Open    |   Open    |
          |-----------+------------+-----------+-----------+-----------|
          |   3.6v    |    Open    |   Open    |  Closed   |   Open    |
          |-----------+------------+-----------+-----------+-----------|
          |    4v     |    Open    |   Open    |   Open    |  Closed   |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                  BUS SPEED CONFIGURATION                   |
          |------------------------------------------------------------|
          |         CPU speed          |             JP29              |
          |----------------------------+-------------------------------|
          |          <= 33MHz          |       pins 1 & 2 closed       |
          |----------------------------+-------------------------------|
          |          > 33MHz           |       pins 2 & 3 closed       |
          +------------------------------------------------------------+