RS-232 C PLUS Upgrade Board  (250-1014)  Features      Faxback Doc. # 5168

The RS-232 C PLUS Upgrade Board, combined with an external modem and the
appropriate software, greatly expands the communications capabilities of your
Tandy 1000 computer so you can:
* Access major information services. (Subscription to services required.)
* "Talk" with other computer as either a host or a terminal computer.
* Use serial printers and plotters.

Notice that we stated "combined with the appropriate software." Even after
you install the RS-232 Board and connect another computer (or some other ex-
ternal device), communication is NOT automatic. It requires an application
program.  For example, you can begin RS-232 communication by taking advantage
of the Telecom and Host, the two telecommunications features included with
your DeskMate package. Telecom lets you access Dow Jones News/Retrieval,
CompuServe, and other information services. Host lets you access the Host
computer from a remote terminal or another computer.

But, what does the RS-232 C Board itself really DO that enables the
communication? Simple. At the communication source, it takes PARALLEL data
(characters transmitted one at a time along one path). At the receiving end,
it converts the data back.

The advantages of serial transmission are that it requires only one
transmission path and that it eliminates problems of data synchronization
associated with parallel transmission.

The term RS-232 C refers to the EIA (Electronics Industries Association)
standard for the interface between the Data Communications Equipment and the
Data Terminal Equipment.

FOR THE ADVANCED USER:
Your RS-232 C Board incorporates a Western Digital WD8250 Asynchronous
Communications Element (ACE) that performs the serial-to-parallel and
parallel-to-serial data conversions. The features of this ACE are discussed
in Chapter 2.

(css 08/03/93)