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# UNIDENTIFIED
STC-SIS486C-DX/SX
Processor 80486SX/80487SX/80486DX
Processor Speed 20/25/33/50MHz
Chip Set SIS
Max. onboard DRAM 32MB
Cache 32/64/128/256KB
BIOS AMI
Dimensions 218mm x 218mm
I/O Options None
NPU Options None
(IMG) IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|---------------------+----------+----------------+----------|
| External battery | J1 | Turbo LED | J6 |
|---------------------+----------+----------------+----------|
| Power LED & keylock | J3 | Turbo switch | J7 |
|---------------------+----------+----------------+----------|
| Speaker | J4 | Reset switch | J8 |
|---------------------+----------+----------------+----------|
| Unknown | J5 | | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Jumper | Position |
|--------------------------------------+--------+------------|
| » | CMOS memory normal operation | J1 | pins 2 & 3 |
| | (internal battery) | | closed |
|---+----------------------------------+--------+------------|
| | CMOS memory normal operation | J1 | pins 1 & 4 |
| | (external battery) | | closed |
|---+----------------------------------+--------+------------|
| | CMOS memory clear | J1 | Open |
|---+----------------------------------+--------+------------|
| » | Monitor type select color | J2 | Closed |
|---+----------------------------------+--------+------------|
| | Monitor type select monochrome | J2 | Open |
|---+----------------------------------+--------+------------|
| » | CPU speed select iOSC/1 | J9 | pins 1 & 2 |
| | | | closed |
|---+----------------------------------+--------+------------|
| | CPU speed select iOSC/2 | J9 | pins 2 & 3 |
| | | | closed |
|---+----------------------------------+--------+------------|
| » | Turbo switch enabled | J10 | Closed |
|---+----------------------------------+--------+------------|
| | Turbo switch disabled | J10 | Open |
+------------------------------------------------------------+
+------------------------------------------------------------+
| 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 |
|------------------+--------------------+--------------------|
| 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 (U26 | Bank 1 (U22 - | Tag | Dirty Bit |
| | - 29) | U25) | | |
|-------+--------------+---------------+---------+-----------|
| 32KB | (4) 8K x 8 | NONE | 8K x 8 | 16K x 4 |
|-------+--------------+---------------+---------+-----------|
| 64KB | (4) 8K x 8 | (4) 8K x 8 | 8K x 8 | 16K x 4 |
|-------+--------------+---------------+---------+-----------|
| 128KB | (4) 32K x 8 | NONE | 32K x 8 | 16K x 4 |
|-------+--------------+---------------+---------+-----------|
| 256KB | (4) 32K x 8 | (4) 32K x 8 | 32K x 8 | 16K x 4 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CACHE JUMPER CONFIGURATION |
|------------------------------------------------------------|
| Size | J11 | J12 | J13 | J14 | J15 | J16 | J17 | J18 | J19 |
|------+-----+-----+-----+-----+-----+-----+-----+-----+-----|
| 32KB |1 & 2|Open |1 & 2|1 & 2|1 & 2|1 & 2|1 & 2|1 & 2|1 & 2|
|------+-----+-----+-----+-----+-----+-----+-----+-----+-----|
| 64KB |2 & 3|Open |1 & 2|2 & 3|1 & 2|1 & 2|2 & 3|1 & 2|1 & 2|
|------+-----+-----+-----+-----+-----+-----+-----+-----+-----|
|128KB |1 & 2|1 & 2|2 & 3|2 & 3|2 & 3|1 & 2|2 & 3|2 & 3|1 & 2|
|------+-----+-----+-----+-----+-----+-----+-----+-----+-----|
|256KB |2 & 3|2 & 3|2 & 3|2 & 3|2 & 3|2 & 3|2 & 3|2 & 3|2 & 3|
|------------------------------------------------------------|
|Note:Pins designated should be in the closed position. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU TYPE CONFIGURATION |
|------------------------------------------------------------|
| Type | J20 | J21 | J22 |
|----------+---------+-------------------+-------------------|
| 80486SX | Closed | pins 1 & 2 closed | pins 1 & 2 closed |
|----------+---------+-------------------+-------------------|
| 80487SX | Closed | pins 1 & 2 closed | pins 2 & 3 closed |
|----------+---------+-------------------+-------------------|
| 80486DX | Open | pins 2 & 3 closed | Open |
+------------------------------------------------------------+