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# DIGITAL EQUIPMENT CORPORATION
VENTURIS 486 (VER. 2.0)
Device Type Mainboard
Processor AM486DX2/P24D/P24T
Processor Speed 25/33/40/50(internal)/66(internal)MHz
Chip Set Unidentified
Video Chip Set S3
Maximum Onboard 68MB
Memory
Maximum Video 1MB
Memory
Cache 128/256KB
BIOS Phoenix
Dimensions 254mm x 218mm
I/O Options Floppy drive interface, IDE interfaces (2),
parallel port, PS/2 mouse port, serial ports
(2), VGA port, riser slot
NPU Options None
(IMG) IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|-----------------+----------+--------------------+----------|
| VGA port | CN1 | Floppy drive | CN6 |
| | | interface | |
|-----------------+----------+--------------------+----------|
| Serial port | CN2 | IDE interface | CN7 |
|-----------------+----------+--------------------+----------|
| Serial port | CN3 | IDE interface | CN8 |
|-----------------+----------+--------------------+----------|
| Parallel port | CN4 | Riser slot | SL1 |
|-----------------+----------+--------------------+----------|
| PS/2 mouse port | CN5 | | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Label | Position |
|-------------------------------------+-------+--------------|
| » | Write through enabled | J1 | Closed |
|---+---------------------------------+-------+--------------|
| | Write back enabled | J1 | Open |
|---+---------------------------------+-------+--------------|
| » | Snoop select enabled | J18 | Pins 1 & 2 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| | Snoop select disabled | J18 | Pins 2 & 3 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| » | On board video enabled | J19 | Pins 2 & 3 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| | On board video disabled | J19 | Pins 1 & 2 |
| | | | closed |
|---+---------------------------------+-------+--------------|
| » | Recovery mode normal operation | J21 | Open |
|---+---------------------------------+-------+--------------|
| | Recovery mode enabled | J21 | Closed |
|---+---------------------------------+-------+--------------|
| » | Password normal operation | J23 | Open |
|---+---------------------------------+-------+--------------|
| | Password clear | J23 | Closed |
|---+---------------------------------+-------+--------------|
| » | Factory configured - do not | SL2 | Unidentified |
| | alter | | |
+------------------------------------------------------------+
+------------------------------------------------------------+
| SIMM CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 | Bank 2 |
|-------------+--------------+---------------+---------------|
| 4MB | 4MB | None | None |
|-------------+--------------+---------------+---------------|
| 8MB | 4MB | (1) 1M x 36 | None |
|-------------+--------------+---------------+---------------|
| 12MB | 4MB | (1) 1M x 36 | (1) 1M x 36 |
|-------------+--------------+---------------+---------------|
| 12MB | 4MB | (1) 2M x 36 | None |
|-------------+--------------+---------------+---------------|
| 16MB | 4MB | (1) 1M x 36 | (1) 2M x 36 |
|-------------+--------------+---------------+---------------|
| 20MB | 4MB | (1) 2M x 36 | (1) 2M x 36 |
|-------------+--------------+---------------+---------------|
| 20MB | 4MB | (1) 4M x 36 | None |
|-------------+--------------+---------------+---------------|
| 24MB | 4MB | (1) 1M x 36 | (1) 4M x 36 |
|-------------+--------------+---------------+---------------|
| 28MB | 4MB | (1) 2M x 36 | (1) 4M x 36 |
|-------------+--------------+---------------+---------------|
| 36MB | 4MB | (1) 4M x 36 | (1) 4M x 36 |
|-------------+--------------+---------------+---------------|
| 36MB | 4MB | (1) 8M x 36 | None |
+------------------------------------------------------------+
+------------------------------------------------------------+
| SIMM CONFIGURATION (CON’T) |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 | Bank 2 |
|--------+----------+------------------------+---------------|
| 40MB | 4MB | (1) 1M x 36 | (1) 8M x 36 |
|--------+----------+------------------------+---------------|
| 44MB | 4MB | (1) 2M x 36 | (1) 8M x 36 |
|--------+----------+------------------------+---------------|
| 52MB | 4MB | (1) 4M x 36 | (1) 8M x 36 |
|--------+----------+------------------------+---------------|
| 68MB | 4MB | (1) 8M x 36 | (1) 8M x 36 |
|------------------------------------------------------------|
| Note: Bank 0 is factory installed and is not |
| configurable. The location is unidentified. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CACHE CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 |
|------------------+--------------------+--------------------|
| 128KB | (4) 32K x 8 | None |
|------------------+--------------------+--------------------|
| 256KB | (4) 32K x 8 | (4) 32K x 8 |
|------------------------------------------------------------|
| Note: The location of the cache is unidentified. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CACHE JUMPER CONFIGURATION |
|------------------------------------------------------------|
| Size | J2 | J4 |
|------------------+--------------------+--------------------|
| 128KB | Pins 1 & 2 closed | Pins 1 & 2 closed |
|------------------+--------------------+--------------------|
| 256KB | Pins 2 & 3 closed | Pins 2 & 3 closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| VIDEO MEMORY CONFIGURATION |
|------------------------------------------------------------|
| Note: Board is factory installed with 1MB cache. The |
| location is unidentified. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU SPEED SELECTION |
|------------------------------------------------------------|
| Speed | J14 | J15 |
|--------------------+-------------------+-------------------|
| 25MHz | Open | Open |
|--------------------+-------------------+-------------------|
| 33MHz | Open | Closed |
|--------------------+-------------------+-------------------|
| 40MHz | Closed | Open |
|--------------------+-------------------+-------------------|
| 50iMHz | Open | Open |
|--------------------+-------------------+-------------------|
| 66iMHz | Open | Closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU TYPE SELECTION |
|------------------------------------------------------------|
| Type | J9 | J35 |
|--------------------+--------------------+------------------|
| AM486DX2 | Pins 2 & 3 closed | Closed |
|--------------------+--------------------+------------------|
| P24D | Pins 1 & 2 closed | Open |
|--------------------+--------------------+------------------|
| P24T | Pins 1 & 2 closed | Open |
+------------------------------------------------------------+