NATURAL MICROSYSTEMS CORPORATION
================================

   DTI-48 REV. 2.4

   Card Type               T1 DSU                                 
   Chip Set                TI TMS320C51                           
   Processor Type          80376 (exact location is unidentified) 
   Processor Speed         Unidentified                           
   I/O options             MVIP bus                               
   Maximum Data Rate       1.544Mbps x 2, 64Kbps x 48             
   Data Bus                16-bit ISA                             
   Data Modulation         B8ZS                                   
   Protocol                

<gopher://bitreich.org/I/th99/t/M-O/51963-1.png>
   

   +------------------------------------------------------------+
   |                        CONNECTIONS                         |
   |------------------------------------------------------------|
   |      Function      | Label |       Function        | Label |
   |--------------------+-------+-----------------------+-------|
   | Line 1 out         |  J1   | Audio handset         |  J3   |
   |--------------------+-------+-----------------------+-------|
   | Line 2 out         |  J2   | MVIP bus              |  J4   |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                 USER CONFIGURABLE SETTINGS                 |
   |------------------------------------------------------------|
   |                 Setting                 | Label | Position |
   |-----------------------------------------+-------+----------|
   |>> | Factory configured - do not alter   | SW2/8 |   Off    |
   |---+-------------------------------------+-------+----------|
   |>> | Factory configured - do not alter   | SW3/8 |   Off    |
   |---+-------------------------------------+-------+----------|
   |>> | Factory configured - do not alter   | P1/E  |   Open   |
   |---+-------------------------------------+-------+----------|
   |>> | Factory configured - do not alter   | P1/F  |   Open   |
   |---+-------------------------------------+-------+----------|
   |>> | Factory configured - do not alter   |  P3   |   Open   |
   |---+-------------------------------------+-------+----------|
   |>> | Factory configured - do not alter   |  P5   |   Open   |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                      BASE I/O ADDRESS                      |
   |------------------------------------------------------------|
   |    Setting     |   S4/1   |   S4/2   |   S4/3   |   S4/4   |
   |----------------+----------+----------+----------+----------|
   |   |    200h    |    On    |    On    |    On    |   Off    |
   |---+------------+----------+----------+----------+----------|
   |>> |    300h    |    On    |    On    |    On    |    On    |
   |---+------------+----------+----------+----------+----------|
   |   |   2200h    |    On    |    On    |   Off    |   Off    |
   |---+------------+----------+----------+----------+----------|
   |   |   2300h    |    On    |    On    |   Off    |    On    |
   |---+------------+----------+----------+----------+----------|
   |   |   4200h    |    On    |   Off    |    On    |   Off    |
   |---+------------+----------+----------+----------+----------|
   |   |   4300h    |    On    |   Off    |    On    |    On    |
   |---+------------+----------+----------+----------+----------|
   |   |   6200h    |    On    |   Off    |   Off    |   Off    |
   |---+------------+----------+----------+----------+----------|
   |   |   6300h    |    On    |   Off    |   Off    |    On    |
   |---+------------+----------+----------+----------+----------|
   |   |   8200h    |   Off    |    On    |    On    |   Off    |
   |---+------------+----------+----------+----------+----------|
   |   |   8300h    |   Off    |    On    |    On    |    On    |
   |---+------------+----------+----------+----------+----------|
   |   |   A200h    |   Off    |    On    |   Off    |   Off    |
   |---+------------+----------+----------+----------+----------|
   |   |   A300h    |   Off    |    On    |   Off    |    On    |
   |---+------------+----------+----------+----------+----------|
   |   |   C200h    |   Off    |   Off    |    On    |   Off    |
   |---+------------+----------+----------+----------+----------|
   |   |   C300h    |   Off    |   Off    |    On    |    On    |
   |---+------------+----------+----------+----------+----------|
   |   |   E200h    |   Off    |   Off    |   Off    |   Off    |
   |---+------------+----------+----------+----------+----------|
   |   |   E300h    |   Off    |   Off    |   Off    |    On    |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                   CABLE LENGTH - LINE 1                    |
   |------------------------------------------------------------|
   |  Setting  | S2/1 | S2/2 | S2/3 | S2/4 | S2/5 | S2/6 | S2/7 |
   |-----------+------+------+------+------+------+------+------|
   |  0'-150'  |  On  | Off  | Off  | Off  | Off  | Off  | Off  |
   |-----------+------+------+------+------+------+------+------|
   | 150'-450' | Off  |  On  | Off  |  On  | Off  |  On  | Off  |
   |-----------+------+------+------+------+------+------+------|
   | 450'-655' | Off  | Off  |  On  | Off  |  On  | Off  |  On  |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                   CABLE LENGTH - LINE 2                    |
   |------------------------------------------------------------|
   |  Setting  | S3/1 | S3/2 | S3/3 | S3/4 | S3/5 | S3/6 | S3/7 |
   |-----------+------+------+------+------+------+------+------|
   |  0'-150'  |  On  | Off  | Off  | Off  | Off  | Off  | Off  |
   |-----------+------+------+------+------+------+------+------|
   | 150'-450' | Off  |  On  | Off  |  On  | Off  |  On  | Off  |
   |-----------+------+------+------+------+------+------+------|
   | 450'-655' | Off  | Off  |  On  | Off  |  On  | Off  |  On  |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                   T1 DIRECTION - LINE 1                    |
   |------------------------------------------------------------|
   |          Setting           |              P8               |
   |----------------------------+-------------------------------|
   |>> |         Normal         |   Pins 1 & 2, 3 & 4 closed    |
   |---+------------------------+-------------------------------|
   |   |        Reversed        |   Pins 1 & 3, 2 & 4 closed    |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                   T1 DIRECTION - LINE 2                    |
   |------------------------------------------------------------|
   |          Setting           |              P10              |
   |----------------------------+-------------------------------|
   |>> |         Normal         |   Pins 1 & 2, 3 & 4 closed    |
   |---+------------------------+-------------------------------|
   |   |        Reversed        |   Pins 1 & 3, 2 & 4 closed    |
   +------------------------------------------------------------+

   +------------------------------------------------------------+
   |                    MVIP BUS TERMINATION                    |
   |------------------------------------------------------------|
   |      Setting       |  P1/A   |  P1/B   |  P1/C   |  P1/D   |
   |--------------------+---------+---------+---------+---------|
   |>> |   Terminated   | Closed  | Closed  | Closed  | Closed  |
   |---+----------------+---------+---------+---------+---------|
   |   | Not terminated |  Open   |  Open   |  Open   |  Open   |
   +------------------------------------------------------------+