VEXTREC TECHNOLOGY, INC.
========================

   GMB-486UN (VER. 3.00)

   Device Type            Mainboard                               
   Processor              80486SX/80486DX/80486DX2                
   Processor Speed        25/33/50/66MHz                          
   Chip Set               Unidentified                            
   Maximum Onboard Memory 32MB DRAM                               
   Cache                  32/64/128/256KB                         
   BIOS                   Acer                                    
   I/O Options            None                                    

<gopher://bitreich.org/I/th99/m/U-Z/35295-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   | External battery   |  JP1   | Turbo LED           |  JP16  |
   |--------------------+--------+---------------------+--------|
   | Reset switch       |  JP14  | Speaker             |  JP17  |
   |--------------------+--------+---------------------+--------|
   | Turbo switch       |  JP15  | Power LED & keylock |  JP18  |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 USER CONFIGURABLE SETTINGS                 |
   |------------------------------------------------------------|
   |             Function             | Label |    Position     |
   |----------------------------------+-------+-----------------|
   |>> | CMOS memory normal operation |  JP2  |   Pins 1 & 2    |
   |   |                              |       |     closed      |
   |---+------------------------------+-------+-----------------|
   |   | CMOS memory clear            |  JP2  |   Pins 2 & 3    |
   |   |                              |       |     closed      |
   |---+------------------------------+-------+-----------------|
   |>> | Hardware emulate KBGA20      | JP10  |   Pins 1 & 2    |
   |   |                              |       |     closed      |
   |---+------------------------------+-------+-----------------|
   |   | Keyboard controller 8042     | JP10  |   Pins 2 & 3    |
   |   |                              |       |     closed      |
   |---+------------------------------+-------+-----------------|
   |>> | Color display enabled        | JP12  |     Closed      |
   |---+------------------------------+-------+-----------------|
   |   | Monochrome display enabled   | JP12  |      Open       |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     DRAM CONFIGURATION                     |
   |------------------------------------------------------------|
   |       Size       |       Bank 0       |       Bank 1       |
   |------------------+--------------------+--------------------|
   |       1MB        |   (4) 256KB x 9    |        None        |
   |------------------+--------------------+--------------------|
   |       2MB        |   (4) 256KB x 9    |   (4) 256KB x 9    |
   |------------------+--------------------+--------------------|
   |       4MB        |    (4) 1MB x 9     |        None        |
   |------------------+--------------------+--------------------|
   |       5MB        |    (4) 1MB x 9     |   (4) 256KB x 9    |
   |------------------+--------------------+--------------------|
   |       8MB        |    (4) 1MB x 9     |    (4) 1MB x 9     |
   |------------------+--------------------+--------------------|
   |       16MB       |    (4) 4MB x 9     |        None        |
   |------------------+--------------------+--------------------|
   |       17MB       |    (4) 4MB x 9     |   (4) 256KB x 9    |
   |------------------+--------------------+--------------------|
   |       20MB       |    (4) 4MB x 9     |    (4) 1KB x 9     |
   |------------------+--------------------+--------------------|
   |       32MB       |    (4) 4MB x 9     |    (4) 4MB x 9     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                    CACHE CONFIGURATION                     |
   |------------------------------------------------------------|
   |   Size    |     Bank 0     |     Bank 1     |     TAG      |
   |-----------+----------------+----------------+--------------|
   |   32KB    |   (4) 8K x 8   |      None      |  (1) 8K x 8  |
   |-----------+----------------+----------------+--------------|
   |   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  |    JP22     |    JP23    |    JP25    |    JP26    |
   |-------+-------------+------------+------------+------------|
   | 32KB  | Pins 2 & 3  | Pins 2 & 3 | Pins 1 & 2 | Pins 2 & 3 |
   |       |   closed    |   closed   |   closed   |   closed   |
   |-------+-------------+------------+------------+------------|
   | 64KB  | Pins 2 & 3  | Pins 2 & 3 | Pins 2 & 3 | Pins 1 & 2 |
   |       |   closed    |   closed   |   closed   |   closed   |
   |-------+-------------+------------+------------+------------|
   | 128KB | Pins 2 & 3  | Pins 1 & 2 | Pins 2 & 3 | Pins 2 & 3 |
   |       |   closed    |   closed   |   closed   |   closed   |
   |-------+-------------+------------+------------+------------|
   | 256KB | Pins 1 & 2  | Pins 2 & 3 | Pins 2 & 3 | Pins 2 & 3 |
   |       |   closed    |   closed   |   closed   |   closed   |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |             CACHE JUMPER CONFIGURATION (CONT.)             |
   |------------------------------------------------------------|
   |   Size    |    JP27    |   JP28    |   JP29    |   JP30    |
   |-----------+------------+-----------+-----------+-----------|
   |   32KB    |   Closed   |   Open    |   Open    |   Open    |
   |-----------+------------+-----------+-----------+-----------|
   |   64KB    |    Open    |  Closed   |   Open    |   Open    |
   |-----------+------------+-----------+-----------+-----------|
   |   128KB   |    Open    |   Open    |  Closed   |   Open    |
   |-----------+------------+-----------+-----------+-----------|
   |   256KB   |    Open    |   Open    |   Open    |  Closed   |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                    CPU SPEED SELECTION                     |
   |------------------------------------------------------------|
   |    Speed     |   JP3    |   JP7   |     JP9      |  JP13   |
   |--------------+----------+---------+--------------+---------|
   |    25MHz     |  2 & 3   |  Open   |    2 & 3     |  2 & 3  |
   |--------------+----------+---------+--------------+---------|
   |    33MHz     |  1 & 2   |  1 & 2  | 1 & 2, 3 & 4 |  1 & 2  |
   |--------------+----------+---------+--------------+---------|
   |  50MHz (DX)  |  2 & 3   |  1 & 2  | 1 & 2, 3 & 4 |  1 & 2  |
   |--------------+----------+---------+--------------+---------|
   | 50MHz (DX2)  |  1 & 2   |  1 & 2  | 1 & 2, 3 & 4 |  1 & 2  |
   |--------------+----------+---------+--------------+---------|
   |    66MHz     |  1 & 2   |  1 & 2  | 1 & 2, 3 & 4 |  1 & 2  |
   +------------------------------------------------------------+