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# 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
IMG IMG 1
+------------------------------------------------------------+
| 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 |
+------------------------------------------------------------+