TANDY/RADIO SHACK
=================

   RS-232 UPGRADE BOARD

   Card Type               Serial card                            
   Chip Set                Unidentified                           
   Maximum Onboard Memory  Unidentified                           
   I/O Options             Serial port                            
   Hard Drives supported   None                                   
   Floppy drives supported None                                   
   Data Bus                SBus                                   
   Card Size               Half-length, full-height card          

<gopher://bitreich.org/I/th99/i/S-T/53509-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   |       Function        | Label |      Function      | Label |
   |-----------------------+-------+--------------------+-------|
   | DB-25 serial port     |  CN1  | Sbus interface     |  CN2  |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |          BASE I/O ADDRESS AND INTERRUPT SELECTION          |
   |------------------------------------------------------------|
   |   Address    |  IRQ  |  SW1/1  |  SW1/2  | SW1/3  | SW1/4  |
   |--------------+-------+---------+---------+--------+--------|
   | COM1 (3F8h)  |   4   |   Off   |   Off   |  Off   |   On   |
   |--------------+-------+---------+---------+--------+--------|
   | COM2 (2F8h)  |   3   |   Off   |   On    |  Off   |   On   |
   |--------------+-------+---------+---------+--------+--------|
   | COM3 (3E8h)  |   4   |   On    |   Off   |  Off   |   On   |
   |--------------+-------+---------+---------+--------+--------|
   | COM3 (3E8h)  |   2   |   On    |   Off   |   On   |   On   |
   |--------------+-------+---------+---------+--------+--------|
   | COM4 (2F8h)  |   3   |   On    |   On    |  Off   |   On   |
   |--------------+-------+---------+---------+--------+--------|
   | COM4 (2F8h)  |   5   |   On    |   On    |   On   |   On   |
   +------------------------------------------------------------+