DD & TT ENTERPRISE USA COMPANY
==============================

   DT-423S4L (Revision C2 and earlier)

   Processor             80486SX/80487SX/80486DX                  
   Processor Speed       20/25/33/50MHz                           
   Chip Set              Symphony                                 
   Max. Onboard DRAM     32MB                                     
   Cache                 64/256/1024KB                            
   BIOS                  AMI/MR                                   
   Dimensions            330mm x 218mm                            
   I/O Options           None                                     
   NPU Options           4167                                     

<gopher://bitreich.org/I/th99/m/C-D/30999-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   | Purpose        | Location | Purpose             | Location |
   |----------------+----------+---------------------+----------|
   | Speaker        |   JP17   | Turbo switch        |   JP20   |
   |----------------+----------+---------------------+----------|
   | Turbo LED      |   JP18   | Power LED & keylock |   JP21   |
   |----------------+----------+---------------------+----------|
   | Reset switch   |   JP19   |                     |          |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 USER CONFIGURABLE SETTINGS                 |
   |------------------------------------------------------------|
   |               Function               | Jumper  | Position  |
   |--------------------------------------+---------+-----------|
   |>>  | Password check disabled         |   JP2   |   Open    |
   |----+---------------------------------+---------+-----------|
   |    | Password check enabled          |   JP2   |  Closed   |
   |----+---------------------------------+---------+-----------|
   |>>  | Post-write buffer wait states   |  JP12   |  Closed   |
   |    | select zero                     |         |           |
   |----+---------------------------------+---------+-----------|
   |    | Post-write buffer wait state    |  JP12   |   Open    |
   |    | select one                      |         |           |
   |----+---------------------------------+---------+-----------|
   |>>  | Cache burst fill cycle select   |  JP16   |   Open    |
   |    | 2-1-1-1                         |         |           |
   |----+---------------------------------+---------+-----------|
   |    | Cache burst fill cycle select   |  JP16   |  Closed   |
   |    | 3-2-2-2                         |         |           |
   |------------------------------------------------------------|
   | Note:The oscillator installed at X1 must match the speed   |
   | of the CPU installed. (iOSC/1)                             |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                     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) 1M x 9     |    (4) 256K x 9    |
   |------------------+--------------------+--------------------|
   |       5MB        |    (4) 256K x 9    |     (4) 1M x 9     |
   |------------------+--------------------+--------------------|
   |       8MB        |     (4) 1M x 9     |     (4) 1M x 9     |
   |------------------+--------------------+--------------------|
   |       16MB       |     (4) 4M x 9     |        NONE        |
   |------------------+--------------------+--------------------|
   |       17MB       |     (4) 4M x 9     |    (4) 256K x 9    |
   |------------------+--------------------+--------------------|
   |       20MB       |     (4) 4M x 9     |     (4) 1M x 9     |
   |------------------+--------------------+--------------------|
   |       20MB       |     (4) 1M x 9     |     (4) 4M x 9     |
   |------------------+--------------------+--------------------|
   |       32MB       |     (4) 4M x 9     |     (4) 4M x 9     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                    CACHE CONFIGURATION                     |
   |------------------------------------------------------------|
   |       Size       |       Bank 0       |        TAG         |
   |------------------+--------------------+--------------------|
   |       64KB       |     (8) 8K x 8     |     (1) 8K x 8     |
   |------------------+--------------------+--------------------|
   |      256KB       |    (8) 32K x 8     |    (1) 32K x 8     |
   |------------------+--------------------+--------------------|
   |      1024KB      |    (8) 128K x 8    |    (1) 128K x 8    |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 CACHE JUMPER CONFIGURATION                 |
   |------------------------------------------------------------|
   |   Size   |   JP8    |   JP9   |  JP11   |  JP13   |  JP14  |
   |----------+----------+---------+---------+---------+--------|
   |   64KB   |  1 & 2   |  1 & 2  |  1 & 2  |  1 & 2  | 1 & 2  |
   |----------+----------+---------+---------+---------+--------|
   |  256KB   |  2 & 3   |  2 & 3  |  2 & 3  |  1 & 2  | 1 & 2  |
   |----------+----------+---------+---------+---------+--------|
   |  1024KB  |  2 & 3   |  2 & 3  |  2 & 3  |  2 & 3  | 2 & 3  |
   |------------------------------------------------------------|
   | Note:Pins designated should be in the closed position.     |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                   CPU TYPE CONFIGURATION                   |
   |------------------------------------------------------------|
   |   Type   |   JP3   |        JP4        |        JP5        |
   |----------+---------+-------------------+-------------------|
   | 80486SX  |  Open   |       Open        | pins 2 & 3 closed |
   |----------+---------+-------------------+-------------------|
   | 80487SX  | Closed  | pins 2 & 3 closed | pins 1 & 2 closed |
   |----------+---------+-------------------+-------------------|
   | 80486DX  | Closed  | pins 1 & 2 closed | pins 1 & 2 closed |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                  CPU SPEED CONFIGURATION                   |
   |------------------------------------------------------------|
   |             Speed             |        JP7        |  JP10  |
   |-------------------------------+-------------------+--------|
   | iOSC/2 (use when CPU speed <= | pins 2 & 3 closed |  Open  |
   | 33MHz)                        |                   |        |
   |-------------------------------+-------------------+--------|
   | iOSC/1 (use when CPU speed >  | pins 1 & 2 closed | Closed |
   | 33MHz)                        |                   |        |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 SYSTEM READY CONFIGURATION                 |
   |------------------------------------------------------------|
   |            Setting            |        JP6        |  JP15  |
   |-------------------------------+-------------------+--------|
   |  SYSTEM READY signal select   | pins 2 & 3 closed | Closed |
   |           extended            |                   |        |
   |-------------------------------+-------------------+--------|
   |  SYSTEM READY signal select   | pins 1 & 2 closed |  Open  |
   |         non-extended          |                   |        |
   +------------------------------------------------------------+