ACER AMERICA CORPORATION
========================

   HMB-16/20

   Card Type          Memory                                      
   Chipset/Controller N/A                                         
   I/O Options        None                                        
   Maximum DRAM       8MB (4MB on HPB supplemental memory card)   

<gopher://bitreich.org/I/th99/i/A-B/50510-1.png>
   

   +------------------------------------------------------------+
   |                      STARTING ADDRESS                      |
   |------------------------------------------------------------|
   |            Address            |            JP1             |
   |-------------------------------+----------------------------|
   |    1.25MB (1MB system RAM)    |     Pins 1 & 2 closed      |
   |-------------------------------+----------------------------|
   |    4.25MB (4MB system RAM)    |     Pins 2 & 3 closed      |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                        PARITY CHECK                        |
   |------------------------------------------------------------|
   |          Enabled           |              JP2              |
   |----------------------------+-------------------------------|
   |>> |        Enabled         |       Pins 2 & 3 closed       |
   |---+------------------------+-------------------------------|
   |   |        Disabled        |       Pins 1 & 2 closed       |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                        MEMORY SIZE                         |
   |------------------------------------------------------------|
   |     Size      |    SW1/1     |    SW1/2     |    SW1/3     |
   |---------------+--------------+--------------+--------------|
   |      2MB      |      On      |      On      |      On      |
   |---------------+--------------+--------------+--------------|
   |      4MB      |     Off      |      On      |      On      |
   |---------------+--------------+--------------+--------------|
   |      6MB      |     Off      |     Off      |      On      |
   |---------------+--------------+--------------+--------------|
   |      8MB      |     Off      |     Off      |     Off      |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                  MEMORY READ/WRITE TIMING                  |
   |------------------------------------------------------------|
   | Card Model/System Speed  | SW1/4 |           TP1           |
   |--------------------------+-------+-------------------------|
   |>>     |  HMB-16/100-ns   |  On   |    Pins 4 & 9, 3 & 8    |
   |       |                  |       |         closed          |
   |-------+------------------+-------+-------------------------|
   |>>     |   HMB-20/85-ns   |  On   |    Pins 4 & 9, 1 & 6    |
   |       |                  |       |         closed          |
   |-------+------------------+-------+-------------------------|
   |       |   HMB-16/85-ns   |  Off  |    Pins 4 & 9, 3 & 9    |
   |       |                  |       |         closed          |
   |-------+------------------+-------+-------------------------|
   |       |  HMB-20/100-ns   |  On   |    Pins 4 & 9, 1 & 6    |
   |       |                  |       |         closed          |
   |------------------------------------------------------------|
   | Note: SW1/4 in the on position enables the zero wait       |
   | state.                                                     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     DRAM CONFIGURATION                     |
   |------------------------------------------------------------|
   |  Size  |  Bank 0  |  Bank 1  | Bank 2  | Bank 3  | Parity  |
   |        |          |          |         |         |  Bits   |
   |--------+----------+----------+---------+---------+---------|
   |  2MB   |   (16)   |   None   |  None   |  None   |   (8)   |
   |        |  514256  |          |         |         | 511000  |
   |--------+----------+----------+---------+---------+---------|
   |  4MB   |   (16)   |   (16)   |  None   |  None   |   (8)   |
   |        |  514256  |  514256  |         |         | 511000  |
   |--------+----------+----------+---------+---------+---------|
   |  6MB   |   (16)   |   (16)   |  (16)   |  None   |   (8)   |
   |        |  514256  |  514256  | 514256  |         | 511000  |
   |--------+----------+----------+---------+---------+---------|
   |  8MB   |   (16)   |   (16)   |  (16)   |  (16)   |   (8)   |
   |        |  514256  |  514256  | 514256  | 514256  | 511000  |
   |------------------------------------------------------------|
   | Note:(1) Banks 2 & 3 are located on the HPB daughter card. |
   |------------------------------------------------------------|
   | (2) The HMB-16 uses 100-ns 514256 RAM chips and 100-ns     |
   | 511000 parity chips.                                       |
   |------------------------------------------------------------|
   | (3) The HMB-20 uses 85-ns 514256 RAM chips and 85-ns       |
   | 511000 parity chips.                                       |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |               MISCELLANEOUS TECHNICAL NOTES                |
   |------------------------------------------------------------|
   |  The HMB-16/20 is for use only in Acer interleaved-memory  |
   |                          systems.                          |
   +------------------------------------------------------------+