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From: TAGLANCE@ucs.UWPLATT.EDU (LANCE TAGLIAPIETRA)
Newsgroups: comp.os.cpm
Subject: Re: Is my machine too SLOW for 2400bps modems?
Message-ID: <C0F22AC9D03FA01F4B@ucs.uwplatt.edu>
Date: 9 Feb 91 02:41:00 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 33

>Darrell Pittman <pittman@mwk.uucp> writes
>
>In article <316@fxrs.intel.com>, jmasters@fxrs.intel.com (Justin Masters) write
   s:
>
>> I'm using Qterm 4.2f and I've also used MEX 1.12 (or some old version like
>> that).  Both worked beautifully for me when I had 1200 baud capability, but
>> now it seems that 2400 baud is too fast.  Is this true?  How do I fix it?  Is
>> it a problem of my machine waiting too long at the end of the line before
>> continuing on to the next line?
>
>    The video driver on your machine is probably too slow in scrolling the
>screen up when it receives a line feed.  Probably the only thing you can do
>is to get the remote system(s) to send you a certain number of NULL characters
>(ASCII 0) after each CR/LF.  Most BBSs have that capability.
>
 
This is exactly what is happening. The serial port is ignored
when the screen is being scrolled. Fortunately there is a
solution to this problem. There is an overlay for MEX version
1.14 for the TRS-80 Model 4 which is interrupt driven. The
interrupt routine runs asynchronously from the modem in routine,
deposting characters into a buffer. The modem in routine which
MEX calls, grabs characters from the buffer.
 
The overlay is available in the MEX area of the cp/m file section
on simtel, under the filename MXO-RS32.ASM.  There are earlier
overlays for the model 4 available, but these do not use the
model 4 interrupts.
 
Hope this helps,
 
Lance Tagliapietra  taglance@ucs.uwplatt.edu or taglance@uwplatt.edu