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From: koonce@wheatena (tim koonce)
Newsgroups: comp.sys.m6809
Subject: Re: rs232 Needed
Message-ID: <1455@cartan.Berkeley.EDU>
Date: Mon, 7-Dec-87 21:50:11 EST
Article-I.D.: cartan.1455
Posted: Mon Dec  7 21:50:11 1987
Date-Received: Sun, 13-Dec-87 08:27:29 EST
References: <15741@watmath.waterloo.edu> <3986@pucc.Princeton.EDU> <1153@wlbr.EATON.COM>
Sender: nobody@cartan.Berkeley.EDU
Reply-To: koonce@bosco.edu (tim koonce)
Distribution: na
Organization: UC Berkeley Math Department
Lines: 36
Summary: 1200bd??  No problem, under the right OS.

In article <1153@wlbr.EATON.COM> pete@wlbr.UUCP (0000-Pete Lyall) writes:
>In article <3986@pucc.Princeton.EDU> EWTILENI@pucc.Princeton.EDU writes:
>>The CoCo 3 can EASILY run 1200 baud out of the bitbanger port on the back
>>of the computer
>
>Wrong. Unless you wish to program the interval timer and poll the bit...
>-- 
>Pete Lyall (OS9 Users Group V.P.)

Here we have an excellent example of OS9 snobbery.  

You're right, but only under OS9.  Under RSDOS, things work
differently.  In fact, programming the interval timer and polling the
bitbanger is pretty easy, and doesn't use up such enormous amounts of
time as you might think, even at 2400 baud, if the routines are
carefully written.  I've done it, and it works.  As a round guess, I
think you could probably get up to 4800 baud and still have about 50%
of the processor time available for foreground stuff, under RSDOS.
Clearly, this won't work well under OS9 because of the overhead time
in servicing interrupts under OS9.  In fact, under OS9, it makes sense
to off-load the processor as much as possible, to allow time for
multitasking.  But if you're single-tasking under RSDOS, and you have
the processor time, it makes a lot of sense to use it, if it can
cut down on hardware costs.

Of course, if you're running a BBS which is probably written in BASIC,
(which I beleive was the original question), then you probably have
enough time problems already, and the RS232pak becomes necessary
again.  (Plus, I abhor switching cables between the modem and printer!
:-)

Tim Koonce
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