Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!nrl-cmf!ames!ucsd!sdcc6!sdcc19!sdcc15!pa1044
From: pa1044@sdcc15.ucsd.edu (pa1044)
Newsgroups: comp.sys.tandy
Subject: Re: Modem routines for the Model 4?
Summary: In BASIC?  Why?
Keywords: model 4, trs80, modem routines
Message-ID: <1041@sdcc15.ucsd.edu>
Date: 6 Feb 89 06:20:03 GMT
References: <2807@m2-net.UUCP>
Reply-To: pa1044@iugrad2.UCSD.EDU (John C. Fowler)
Distribution: usa
Organization: University of California, San Diego
Lines: 34

In article <2807@m2-net.UUCP> arkie@m-net.UUCP (Joseph Wisdom) writes:
>I am looking for modem routines for the reading of, and the writing
>to the modem output port for a Model 4 computer, in BASIC.

If you mean in Model 4 mode, that would be pretty difficult.  The
two best ways to monitor the RS-232C (that's the modem port) are:
1) To use the RS-232 interrupt.  This requires machine language to
set up.
2) To use the COM/DVR driver to set up its own interrupt.  This
requires that you make supervisor calls to receive and send
characters, which also require some minimal machine code.

If the reason you want this is for some BASIC application in Model 4
mode, and you don't want to fool around with assembly language, I
strongly suggest that you look around for a Model 4 host program.
This interfaces with the normal screen and keyboard routines so that
anything normally sent to the screen is also sent to the RS-232, and
anything coming from the RS-232 is treated as if it came from the
keyboard.  If you can't find a host program, you can easily simulate
one by using the COM/DVR, and using the TRSDOS/LS-DOS command LINK.

I imagine that it is possible to use the RS-232 port using only
BASIC commands (I KNOW it's possible in Model III mode, so it's
probably possible in Model 4 mode).  This would just involve regular
INP and OUT commands to various ports.  However, considering the
speed of BASIC, the fastest you'll be able to go is about 110 baud,
and even less if you want to do something besides display the
characters on the screen and send keyboard output to the RS-232.

-- 
John C. Fowler, pa1044@iugrad2.UCSD.EDU  (I could list others, but why?)
Disclaimer: Could you imagine the ramifications if the Regents of the
	    University of California held MY opinions?
--