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                                          

<gopher://bitreich.org/I/th99/m/C-D/35188-1.png>
   

   +------------------------------------------------------------+
   |                        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       |
   +------------------------------------------------------------+