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# J-MARK COMPUTER CORPORATION
JET-486DX/SX 20/25 NON-CACHE
Processor 80486SX/80486DX
Processor Speed 20/25/33MHz
Chip Set ETEQ
Max. Onboard DRAM 32MB
Cache None
BIOS AMI
Dimensions 220mm x 220mm
I/O Options None
NPU Options 80487SX
IMG IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|-------------------+----------+------------------+----------|
| Reset switch | J1 | Turbo switch | J4 |
|-------------------+----------+------------------+----------|
| Power LED & | J2 | External battery | JP1 |
| keylock | | | |
|-------------------+----------+------------------+----------|
| Speaker | J3 | Turbo LED | JP5 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Jumper | Position |
|--------------------------------------+--------+------------|
| » | Monitor type select color | JP2 | Closed |
|---+----------------------------------+--------+------------|
| | Monitor type select monochrome | JP2 | Open |
|---+----------------------------------+--------+------------|
| » | CMOS memory normal operation | JP3 | Closed |
|---+----------------------------------+--------+------------|
| | CMOS memory clear | JP3 | Open |
|---+----------------------------------+--------+------------|
| » | Factory configured - do not | JP12 | Closed |
| | alter | | |
|---+----------------------------------+--------+------------|
| » | Oscillator speed select 25MHz | JP13 | pins 1 & 2 |
| | | | closed |
|---+----------------------------------+--------+------------|
| | Oscillator speed select 20MHz | JP13 | pins 2 & 3 |
| | | | 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) 1 M x 9 |
|------------------+--------------------+--------------------|
| 8MB | (4) 1M x 9 | (4) 1M x 9 |
|------------------+--------------------+--------------------|
| 16MB | (4) 4M x 9 | NONE |
|------------------+--------------------+--------------------|
| 32MB | (4) 4M x 9 | (4) 4M x 9 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU TYPE CONFIGURATION |
|------------------------------------------------------------|
| Type | JP8 | JP9 | JP10 | JP11 |
|---------+--------+--------+-------------------+------------|
| 80486SX | Open | Open | pins 1 & 2 closed | pins 1 & 2 |
| | | | | closed |
|---------+--------+--------+-------------------+------------|
| 80487SX | Closed | Open | Open | pins 2 & 3 |
| | | | | closed |
|---------+--------+--------+-------------------+------------|
| 80486DX | Closed | Closed | pins 2 & 3 closed | pins 1 & 2 |
| | | | | closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CHIPSET TYPE CONFIGURATION |
|------------------------------------------------------------|
| Type | JP6 | JP7 | JP14 | JP15 |
|--------+------------+------------+------------+------------|
| 82C493 | pins 1 & 2 | pins 2 & 3 | pins 2 & 3 | pins 1 & 2 |
| | closed | closed | closed | closed |
|--------+------------+------------+------------+------------|
| 82C492 | pins 2 & 3 | pins 1 & 2 | pins 1 & 2 | pins 2 & 3 |
| | closed | closed | closed | closed |
+------------------------------------------------------------+