300 BPS DCM-2 Modem (260-1173)      Videotex           Faxback Doc. # 5983

USING THE MODEM II WITH VIDEOTEX SOFTWARE
A Modem that is connected to a Computer running a TRS-80 Videotex software
package constitutes one of the most common ways to use your Modem II. This
section will describe how to use the Modem II with VIDEOTEX on TRS-80 Model
I, II, III, and Color Computers.

If you're interested in writing you own programs for the Modem II, refer to
the section of this manual entitled TECHNICAL AND PROGRAMMING INFORMATION. 
It will give you a detailed account of how the Modem II works but on a tech-
nical level.

MANUAL VS. AUTOMATIC OPERATION
If you want to dial an information service (such as CompuServe or Dow Jones)
or communicate with another person whose computer is also using VIDTEX, you
can set the appropriate MODE Switch to MAN (manual). In this mode, you con-
trol what the System does by "manually" dialing and answering the phone.

If you want the modem to dial a phone number (or answer the phone) for you,
set the appropriate MODE Switch to AUTO (automatic). In this mode, the Modem
dials the phone number you specify or answers the phone when someone calls
you. Automatic Mode, for instance, lets you dial the information service
number without picking up the phone--just type the number (along with the
proper Modem II programming commands) on the Computer keyboard. (In other
words, let your fingers do the walking--but on the keyboard instead of the
telephone!)

ORIGINATE VS. ANSWER MODES
If you want to place a call (to an information service or another person us-
ing VIDTEX), set the other MODE Switch to ORIGinate. In this mode, the call
"originates" from your computer.

If you want to receive a call (e.g., answer the phone), set the appropriate
MODE Switch to ANSwer.

Note that Originate and Answer Modes can be used either manually or
automatically. That is, you can set the MODE Switches to MAN/ORIG, MAN/ANS,
AUTO/ORIG, or AUTO/ANS depending on your particular needs.

During communication, you can also change the MODE Switch settings without
interfering with communications. When you disconnect from the information
service, however, the Modem will automatically go to the "new" mode. For
example, if the  MODE Switches are set to MAN/ORIG (the most common setting
when communicating with an information service) and you want to switch to
AUTO/ANS on disconnect, just change the settings before you sign off. The
Modem II will begin waiting for a call and automatically answer the phone
after it disconnects from the service.

If you set the TEST Switch to REMote while communicating with an information
service, the Modem will simulate half-duplex communication and the Host sys-
tem may send you "double characters".

VIDEOTEX AND THE MODEM II
Videotex software packages that allow you to communicate with an information
service or with other Videotex users over the phone, are available for TRS-
80 Models I,II,III, and Color Computers. For specific details on using an
information service user's guide.

Color Computer users should always remember to set the FORCE DTR Switch to
ON.  We suggest that other TRS-80 users also keep the FORCE DTR set to ON 
unless your program explicitly calls for FORCE DTR to be OFF.

(css 08/04/93)