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# FOREX COMPUTER CORPORATION
FOREX 486 (REV. VL3H)
Processor 80486SX/80487SX/80486DX/80486DX2/P23T/P24T
Processor Speed 20/25/33/40/50(internal)/50/66(internal)MHz
Chip Set Forex
Video Chip Set None
Maximum Onboard 32MB
Memory
Maximum Video None
Memory
Cache 64/128/256KB
BIOS AMI
Dimensions 260mm x 220mm
I/O Options 32-bit VESA local bus slots (3), green PC
connector
NPU Options None
(IMG) IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|---------------+----------+----------------------+----------|
| Turbo LED | J6 | External battery | JP1 |
|---------------+----------+----------------------+----------|
| Speaker | J7 | Green PC connector | JP14 |
|---------------+----------+----------------------+----------|
| Turbo switch | J8 | Green PC LED | JP15 |
|---------------+----------+----------------------+----------|
| Power LED & | J9 | 32-bit VESA local | SL1 – |
| keylock | | bus slots | SL3 |
|---------------+----------+----------------------+----------|
| Reset switch | J10 | | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Label | Position |
|------------------------------------+-------+---------------|
| | PQFP CPU enabled | JP5 | Open |
|---+--------------------------------+-------+---------------|
| | PQFP CPU disabled | JP5 | Closed |
|---+--------------------------------+-------+---------------|
| » | CMOS memory normal operation | JP6 | Unidentified |
|---+--------------------------------+-------+---------------|
| | CMOS memory clear | JP6 | Unidentified |
|---+--------------------------------+-------+---------------|
| | Green PC disabled | JP13 | Open |
|---+--------------------------------+-------+---------------|
| | Green PC enabled | JP13 | Closed |
|---+--------------------------------+-------+---------------|
| | Green clock speed select 8MHz | JP16 | Pins 2 & 3 |
| | | | closed |
|---+--------------------------------+-------+---------------|
| | Green clock speed select 16MHz | JP16 | Pins 1 & 2 |
| | | | 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 | Bank 0 | Bank 1 | TAG |
|----------+---------------+---------------+-----------------|
| 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) 16K/32K x 8 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CACHE JUMPER CONFIGURATION |
|------------------------------------------------------------|
| Size | JP8A | JP8B | JP8C |
|-------+-----------------+-----------------+----------------|
| 64KB | Pins 2 & 3 | Pins 1 & 2 | Pins 2 & 3 |
| | closed | closed | closed |
|-------+-----------------+-----------------+----------------|
| 128KB | Pins 1 & 2 | Pins 2 & 3 | Pins 1 & 2 |
| | closed | closed | closed |
|-------+-----------------+-----------------+----------------|
| 256KB | Pins 1 & 2 | Pins 1 & 2 | Pins 1 & 2 |
| | closed | closed | closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU SPEED SELECTION |
|------------------------------------------------------------|
| Speed | JP7A | JP7B | JP7C |
|---------------+--------------+--------------+--------------|
| 20MHz | Open | Closed | Closed |
|---------------+--------------+--------------+--------------|
| 25MHz | Closed | Open | Open |
|---------------+--------------+--------------+--------------|
| 33MHz | Open | Open | Open |
|---------------+--------------+--------------+--------------|
| 40MHz | Closed | Closed | Open |
|---------------+--------------+--------------+--------------|
| 50iMHz | Closed | Open | Open |
|---------------+--------------+--------------+--------------|
| 50MHz | Open | Closed | Open |
|---------------+--------------+--------------+--------------|
| 66iMHz | Open | Open | Open |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU TYPE SELECTION |
|------------------------------------------------------------|
| Type | JP2 | JP3 | JP4 | JP12 |
|-----------+------------+-----------+-----------+-----------|
| 80486SX | Pins 2 & 3 | Pins 2 & | Pins 2 & | Pins 1 & |
| | closed | 3 closed | 3 closed | 2 closed |
|-----------+------------+-----------+-----------+-----------|
| 80487SX | Pins 2 & 3 | Pins 1 & | Pins 1 & | Pins 1 & |
| | closed | 2 closed | 2 closed | 2 closed |
|-----------+------------+-----------+-----------+-----------|
| 80486DX | Pins 2 & 3 | Pins 2 & | Pins 2 & | Pins 1 & |
| (PQFP) | closed | 3 closed | 3 closed | 2 closed |
|-----------+------------+-----------+-----------+-----------|
| 80486DX | Pins 1 & 2 | Pins 1 & | Pins 1 & | Pins 1 & |
| (PGA) | closed | 2 closed | 2 closed | 2 closed |
|-----------+------------+-----------+-----------+-----------|
| 80486DX2 | Pins 1 & 2 | Pins 1 & | Pins 1 & | Pins 1 & |
| | closed | 2 closed | 2 closed | 2 closed |
|-----------+------------+-----------+-----------+-----------|
| P23T | Pins 2 & 3 | Pins 1 & | Pins 1 & | Pins 1 & |
| | closed | 2 closed | 2 closed | 2 closed |
|-----------+------------+-----------+-----------+-----------|
| P24T | Pins 1 & 2 | Pins 1 & | Pins 1 & | Pins 2 & |
| | closed | 2 closed | 2 closed | 3 closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU TYPE SELECTION (CYRIX ONLY) |
|------------------------------------------------------------|
| Type | JP20 |
|-------------------------------+----------------------------|
| CX486DX | Open |
|-------------------------------+----------------------------|
| CX486DX2 | Closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| VL BUS WAIT STATE SELECTION |
|------------------------------------------------------------|
| Setting | JP10 |
|----------------------------+-------------------------------|
| 0 | Pins 1 & 2 closed |
|----------------------------+-------------------------------|
| 1 | Pins 2 & 3 closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| VL BUS SPEED SELECTION |
|------------------------------------------------------------|
| Speed | JP11 |
|----------------------------+-------------------------------|
| <= 33MHz | Pins 1 & 2 closed |
|----------------------------+-------------------------------|
| >33 MHz | Pins 2 & 3 closed |
+------------------------------------------------------------+