Below are instructions on how to construct a null modem cable for the
purposes of transferring data between a Model 16/16B/6000 and an IBM
Compatible computer via some communications program like kermit running
on both machines or some other configuration.  Under MSDOS, a user would
call up the TRS80 Xenix machine via any communications program running 
as a terminal, login, start the data transfer on the Xenix machine, and
return to MSDOS to receive the download.

                       DB-25 TO DB-25

           Tandy                     IBM COMPATIBLE
     DB-25 Connector                 DB-25 Connector
        FUNCTION    Pin             Pin     FUNCTION
    ___________________             ___________________
    | Sig. Grnd   | 7 |             | 7 | Sig. Grnd   |
    |             |   |             |   |             |
    | Trans. Data | 2 |             | 3 | Rec. Data   |
    |             |   |             |   |             |
    | Rec. Data   | 3 |             | 2 | Trans. Data |
    |             |   |             |   |             |
    | DTR         | 20|             | 6 | DSR         |
    |             |   |             |   |             |
    | DSR         | 6 |             | 20| DTR         |
    |             |   |             |   |             |
    |             |   | Joined > \--| 5 |Clear to Send|
    |             |   |           \ |   |             |
    | Carrier Det.| 8 |------------\| 4 |Req. to Send |
    |_____________|___|             |___|_____________|



                        DB-25 TO DB-9

           Tandy                     IBM COMPATIBLE
     DB-25 Connector                 DB-9 Connector
        FUNCTION    Pin             Pin     FUNCTION
    ___________________             ___________________
    | Sig. Grnd   | 7 |             | 5 | Sig. Grnd   |
    |             |   |             |   |             |
    | Trans. Data | 2 |             | 2 | Rec. Data   |
    |             |   |             |   |             |
    | Rec. Data   | 3 |             | 3 | Trans. Data |
    |             |   |             |   |             |
    | DTR         | 20|             | 6 | DSR         |
    |             |   |             |   |             |
    | DSR         | 6 |             | 4 | DTR         |
    |             |   |             |   |             |
    |             |   | Joined > \--| 8 |Clear to Send|
    |             |   |           \ |   |             |
    | Carrier Det.| 8 |------------\| 7 |Req. to Send |
    |_____________|___|             |___|_____________|