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# ABIT COMPUTER CORPORATION
AS420/AS425/AS433/AS455
Processor 80486SX/80486DX
Processor Speed 20/25/33/40MHz
Chip Set SIS
Max. Onboard DRAM 32MB
Cache 32/64/128/256/512/1024KB
BIOS AMI
Dimensions 330mm x 214mm
I/O Options None
NPU Options 4167
IMG IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|------------------+----------+-------------------+----------|
| Turbo LED | D6 | Reset | JP20 |
|------------------+----------+-------------------+----------|
| External battery | JP15 | Speaker | JP21 |
|------------------+----------+-------------------+----------|
| Turbo switch | JP19 | Power LED & | JP22 |
| | | keylock | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Jumper | Position |
|--------------------------------------+--------+------------|
| » | Factory configured - do not | JP2 | Open |
| | alter | | |
|---+----------------------------------+--------+------------|
| » | Monitor type select monochrome | JP4 | Open |
|---+----------------------------------+--------+------------|
| | Monitor type select color | JP4 | Closed |
|---+----------------------------------+--------+------------|
| » | CMOS memory normal operation | JP5 | pins 1 & 2 |
| | | | closed |
|---+----------------------------------+--------+------------|
| | CMOS memory clear | JP5 | pins 2 & 3 |
| | | | closed |
|---+----------------------------------+--------+------------|
| » | Factory configured - do not | JP6 | pins 1 & 2 |
| | alter | | closed |
|---+----------------------------------+--------+------------|
| » | Factory configured - do not | JP8 | pins 1 & 2 |
| | alter | | closed |
|---+----------------------------------+--------+------------|
| » | Factory configured - do not | JP14 | pins 1 & 2 |
| | alter | | closed |
|---+----------------------------------+--------+------------|
| » | Factory configured - do not | JP17 | pins 1 & 2 |
| | alter | | 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 |
|------------------+--------------------+--------------------|
| 8MB | (4) 1M x 9 | (4) 1M x 9 |
|------------------+--------------------+--------------------|
| 16MB | (4) 4M x 9 | NONE |
|------------------+--------------------+--------------------|
| 32MB | (4) 4M x 9 | (4) 4M x 9 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CACHE CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 | TAG (U28 & | TAG (U30) |
| | | | U29) | |
|--------+------------+------------+------------+------------|
| 32KB | (4) 8K x 8 | NONE | (2) 16K x | NONE |
| | | | 4 | |
|--------+------------+------------+------------+------------|
| 32KB | (4) 8K x 8 | NONE | NONE | (1) 8K x 8 |
|--------+------------+------------+------------+------------|
| 64KB | (4) 8K x 8 | (4) 8K x 8 | (2) 16K x | NONE |
| | | | 4 | |
|--------+------------+------------+------------+------------|
| 64KB | (4) 8K x 8 | (4) 8K x 8 | NONE | (1) 8K x 8 |
|--------+------------+------------+------------+------------|
| 128KB | (4) 32K x | NONE | (2) 64K x | NONE |
| | 8 | | 4 | |
|--------+------------+------------+------------+------------|
| 128KB | (4) 32K x | NONE | NONE | (1) 32K x |
| | 8 | | | 8 |
|--------+------------+------------+------------+------------|
| 256KB | (4) 32K x | (4) 32K x | (2) 16K x | NONE |
| | 8 | 8 | 4 | |
|--------+------------+------------+------------+------------|
| 256KB | (4) 32K x | (4) 32K x | NONE | (1) 32K x |
| | 8 | 8 | | 8 |
|--------+------------+------------+------------+------------|
| 512KB | (4) 128K x | NONE | NONE | (1) 128K x |
| | 8 | | | 8 |
|--------+------------+------------+------------+------------|
| 1024KB | (4) 128K x | (4) 128K x | (2) 64K x | NONE |
| | 8 | 8 | 4 | |
|--------+------------+------------+------------+------------|
| 1024KB | (4) 128K x | (4) 128K x | NONE | (1) 128K x |
| | 8 | 8 | | 8 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CACHE JUMPER CONFIGURATION |
|------------------------------------------------------------|
| Size | JP28 | JP30 | JP31 | JPX1/JPX2 | JPX3 | JPX4 |
|--------+-------+--------+--------+-----------+------+------|
| 32KB | 2 & 3 | Open | Closed | 1 - 8 | Open | 1 - |
| | | | | | | 16 |
|--------+-------+--------+--------+-----------+------+------|
| 64KB | 1 & 2 | Closed | Open | 1 - 8 | 1 - | Open |
| | | | | | 16 | |
|--------+-------+--------+--------+-----------+------+------|
| 128KB | 1 & 2 | Closed | Closed | 3 - 10 | 1 - | Open |
| | | | | | 16 | |
|--------+-------+--------+--------+-----------+------+------|
| 256KB | 1 & 2 | Closed | Open | 5 - 12 | 1 - | Open |
| | | | | | 16 | |
|--------+-------+--------+--------+-----------+------+------|
| 512KB | 1 & 2 | Closed | Open | 7 - 14 | Open | 1 - |
| | | | | | | 16 |
|--------+-------+--------+--------+-----------+------+------|
| 1024KB | 1 & 2 | Closed | Closed | 9 - 18 | 1 - | Open |
| | | | | | 16 | |
|------------------------------------------------------------|
| Note: Jumpers JPX1-JPX4 are closed using one or two 8-pin |
| terminating resistors. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU TYPE CONFIGURATION |
|------------------------------------------------------------|
| Type | JP25 | JPX5 |
|--------------------+-------------------+-------------------|
| 80486SX | Closed | Open |
|--------------------+-------------------+-------------------|
| 80486DX | Open | Closed |
+------------------------------------------------------------+