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Message-ID: <5.1.0.14.0.20020610203655.02c68b80@POP2.sympatico.ca>
Date: Mon, 10 Jun 2002 20:48:47 -0400
To: rsgb_lf_group@blacksheep.org,  rsgb_lf_group@blacksheep.org
From: "Larry Kayser" <kayser@sympatico.ca>
Subject: Re: LF: Programming !!!HELP!!!
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>Brian:

>  Some progress has been made in that I am now
>able to commnicate serially through a COM port using a simple
>QB45 routine running in a DOS box under ME at 9600 and
>inconsistently at 19200.  73, Brian

Really!  Well take a scope and watch the incoming data at both speeds and 
make sure that the start bit directly follows the preceding stop bit, no 
extra time allowed.  Bet you find your not quite doing what you thing your 
doing.  If you get errors when there is ZERO extra time then you have a 
problem sitting in the bush waiting to catch you.

Some years ago I was paid to disassemble some functions of QB 4.5 and find 
out what was going on in the code, unless you are running a very fast 
Pentium you will find there is a little bomb waiting for you when incoming 
data is going at machine rate, ie no extra wasted time between stop and 
start bits.

It can look good but then when you have invested hundreds of hours of 
programming you might find a nasty waiting to take you on.  My standard 
test here, because of the 18 millisecond interrupt in a PC, is to make the 
machine faultlessly handle coms for several weeks without 
failure.  Remember MS makes no statements ever about the maximum return 
time from the 18 ms interrupt, it can take up to several hundred 
milliseconds and if your running at machine rate only a buffer of 16K or 
larger can keep the game sane.

Good Luck.

PS under VB6 we now use minimum buffer size of 32K and my partner Jim has 
just been working with a new beta release of MS VB and tells me he sees the 
machine wants to assign up to 256K to the buffer for each com port.

PPS, are you active on 144 MHz with a big signal by chance?

Larry
VA3LK