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# J-MARK COMPUTER CORPORATION
J-646B
Processor Pentium
Processor Speed 75/90/100/120/133/150/166MHz
Chip Set SIS
Video Chip Set None
Maximum Onboard 128MB (EDO supported)
Memory
Maximum Video None
Memory
Cache 256/512/1024KB
BIOS Award
Dimensions 330mm x 218mm
I/O Options 32-bit PCI slots (3), floppy drive interface,
IDE interfaces (2), parallel port, PS/2 mouse
interface, serial ports (2)
NPU Options None
IMG IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|-------------------+----------+------------------+----------|
| Speaker | CN1 | Serial port 2 | J8 |
|-------------------+----------+------------------+----------|
| Reset switch | CN2 | Serial port 1 | J9 |
|-------------------+----------+------------------+----------|
| Turbo LED | CN3 | Parallel port | J10 |
|-------------------+----------+------------------+----------|
| Power LED & | CN4 | Floppy drive | J11 |
| keylock | | interface | |
|-------------------+----------+------------------+----------|
| Turbo switch | CN5 | IDE interface 1 | J12 |
|-------------------+----------+------------------+----------|
| IDE interface LED | CN6 | IDE interface 2 | J13 |
|-------------------+----------+------------------+----------|
| BK LED | CN7 | External battery | J15 |
|-------------------+----------+------------------+----------|
| PS/2 mouse | J2 | 32-bit PCI slots | PC1 – |
| interface | | | PC3 |
|-------------------+----------+------------------+----------|
| VGA feature | J7 | | |
| connector | | | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Label | Position |
|-------------------------------------+-------+--------------|
| » | Factory configured - do not | J6 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP4 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP5 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP6 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP7 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP9 | Open |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP15 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | CPU write select write back | JP16 | Pins 1 & 2 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| | CPU write select write through | JP16 | Pins 2 & 3 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| » | CPU pipeline enabled | JP17 | Pins 2 & 3 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| | CPU pipeline disabled | JP17 | Pins 1 & 2 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| » | Suspend mode disabled | JP20 | Open |
|---+---------------------------------+-------+--------------|
| | Suspend mode enabled | JP20 | Closed |
|---+---------------------------------+-------+--------------|
| » | Break switch for suspend mode | JP24 | Pins 2 & 3 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| | 8042 RC enabled | JP24 | Pins 1 & 2 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| » | Monitor type select monochrome | JP25 | Open |
|---+---------------------------------+-------+--------------|
| | Monitor type select color | JP25 | Closed |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP26 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP27 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP28 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP29 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP30 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP31 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP32 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP33 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP34 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP35 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP36 | Unidentified |
| | alter | | |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP37 | Unidentified |
| | alter | | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS (CON’T) |
|------------------------------------------------------------|
| Function | Label | Position |
|-------------------------------------+-------+--------------|
| » | CMOS memory normal operation | JP38 | Pins 1 & 2 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| | CMOS memory clear | JP38 | Pins 2 & 3 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| » | PCICLK speed select 1/2 CPU CLK | JP39 | Closed |
|---+---------------------------------+-------+--------------|
| | PCICLK speed select = 32MHz | JP39 | Open |
|---+---------------------------------+-------+--------------|
| » | PS/2 IRQ12 enabled | JP41 | Closed |
|---+---------------------------------+-------+--------------|
| | PS/2 IRQ12 disabled | JP41 | Open |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | JP42 | Unidentified |
| | alter | | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| DRAM CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 | Bank 2 | Bank 3 |
|--------+------------+------------+------------+------------|
| 4MB | (1) 1M x | None | None | None |
| | 36 | | | |
|--------+------------+------------+------------+------------|
| 8MB | (1) 2M x | None | None | None |
| | 36 | | | |
|--------+------------+------------+------------+------------|
| 8MB | (1) 1M x | (1) 1M x | None | None |
| | 36 | 36 | | |
|--------+------------+------------+------------+------------|
| 16MB | (1) 4M x | None | None | None |
| | 36 | | | |
|--------+------------+------------+------------+------------|
| 16MB | (1) 2M x | (1) 2M x | None | None |
| | 36 | 36 | | |
|--------+------------+------------+------------+------------|
| 16MB | (1) 1M x | (1) 1M x | (1) 1M x | (1) 1M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 24MB | (1) 1M x | (1) 1M x | (1) 2M x | (1) 2M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 32MB | (1) 8M x | None | None | None |
| | 36 | | | |
|--------+------------+------------+------------+------------|
| 32MB | (1) 4M x | (1) 4M x | None | None |
| | 36 | 36 | | |
|--------+------------+------------+------------+------------|
| 32MB | (1) 2M x | (1) 2M x | (1) 2M x | (1) 2M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 40MB | (1) 4M x | (1) 4M x | (1) 1M x | (1) 1M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 48MB | (1) 4M x | (1) 4M x | (1) 2M x | (1) 2M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 64MB | (1) 4M x | (1) 4M x | (1) 4M x | (1) 4M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 72MB | (1) 8M x | (1) 8M x | (1) 1M x | (1) 1M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 80MB | (1) 8M x | (1) 8M x | (1) 2M x | (1) 2M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 96MB | (1) 8M x | (1) 8M x | (1) 4M x | (1) 4M x |
| | 36 | 36 | 36 | 36 |
|--------+------------+------------+------------+------------|
| 128MB | (1) 8M x | (1) 8M x | (1) 8M x | (1) 8M x |
| | 36 | 36 | 36 | 36 |
|------------------------------------------------------------|
| Note: Board accepts EDO memory. Board also accepts x 32 |
| SIMMs. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| DRAM VOLTAGE CONFIGURATION |
|------------------------------------------------------------|
| Voltage | JP1 |
|----------------------------+-------------------------------|
| » | Mixed mode | Pins 3 & 5, 4 & 6 closed |
|---+------------------------+-------------------------------|
| | 3.3v | Pins 1 & 3, 2 & 4 closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CACHE CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 | TAG |
|-----------+--------------+--------------+------------------|
| 256KB (A) | None | (8) 32K x 8 | (1) 8K x 8 |
|-----------+--------------+--------------+------------------|
| 256KB (B) | (2) 32K x 32 | None | Unidentified |
|-----------+--------------+--------------+------------------|
| 512KB (A) | None | (8) 64K x 8 | (1) 16K x 8 |
| | | | (Windbond) |
|-----------+--------------+--------------+------------------|
| 512KB (B) | None | (8) 64K x 8 | (1) 16K/32K x 8 |
| | | | (Aster) |
|-----------+--------------+--------------+------------------|
| 1MB | None | (8) 128K x 8 | (1) 32K x 8 |
|------------------------------------------------------------|
| Note: The location of bank 1 & TAG are unidentified. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CACHE JUMPER CONFIGURATION |
|------------------------------------------------------------|
| Size | JP3 | JP11 | JP42 |
|-----------+-------------------+-------------------+--------|
| 256KB (A) | Pins 1 & 2 closed | Pins 1 & 2 closed | Open |
|-----------+-------------------+-------------------+--------|
| 256KB (B) | Pins 1 & 2 closed | Pins 1 & 2 closed | Open |
|-----------+-------------------+-------------------+--------|
| 512KB (A) | Pins 2 & 3 closed | Open | Closed |
|-----------+-------------------+-------------------+--------|
| 512KB (B) | Pins 2 & 3 closed | Pins 1 & 2 closed | Open |
|-----------+-------------------+-------------------+--------|
| 1MB | Pins 2 & 3 closed | Pins 2 & 3 closed | Open |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU SPEED SELECTION |
|------------------------------------------------------------|
|CPU speed|Clock speed|Multiplier| JP12 | JP13 | JP18 | JP19 |
|---------+-----------+----------+------+------+------+------|
| 75MHz | 50MHz | 1.5x |Closed|Closed| Open | Open |
|---------+-----------+----------+------+------+------+------|
| 90MHz | 60MHz | 1.5x |Closed| Open | Open | Open |
|---------+-----------+----------+------+------+------+------|
| 100MHz | 66MHz | 1.5x | Open |Closed| Open | Open |
|---------+-----------+----------+------+------+------+------|
| 120MHz | 60MHz | 2x |Closed| Open | Open |Closed|
|---------+-----------+----------+------+------+------+------|
| 133MHz | 66MHz | 2x | Open |Closed| Open |Closed|
|---------+-----------+----------+------+------+------+------|
| 150MHz | 60MHz | 2.5x |Closed| Open |Closed|Closed|
|---------+-----------+----------+------+------+------+------|
| 166MHz | 66MHz | 2.5x | Open |Closed|Closed|Closed|
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU VOLTAGE SELECTION |
|------------------------------------------------------------|
| Voltage | JP21 | JP22 | JP23 |
|-----------------+--------------+-------------+-------------|
| | 3.3v | Closed | Open | Open |
|---+-------------+--------------+-------------+-------------|
| » | 3.45v | Open | Closed | Open |
|---+-------------+--------------+-------------+-------------|
| | 3.6v | Open | Open | Closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| VGA SELECTION |
|------------------------------------------------------------|
| Setting | JP2 | JP8 | JP10 |
|-----------------------+------------------+--------+--------|
| » | Onboard VGA | Pins 1 & 2 | Closed | Closed |
| | | closed | | |
|---+-------------------+------------------+--------+--------|
| | External VGA card | Pins 2 & 3 | Open | Open |
| | | closed | | |
+------------------------------------------------------------+