From:	Jason Green <news AT jgreen4 DOT fsnet DOT co DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: com1 programming .... a lot of question
Date:	Thu, 18 May 2000 22:35:17 +0100
Organization:	Customer of Planet Online
Lines:	19
Message-ID:	<37o8isgacarhus3cs90u00js9ioi88501d@4ax.com>
References:	<3923FCF4 DOT DC4FBBAD AT mtu-net DOT ru> <Pine DOT SUN DOT 3 DOT 91 DOT 1000518184115 DOT 15189S-100000 AT is>
NNTP-Posting-Host:	modem-79.arizona.dialup.pol.co.uk
Mime-Version:	1.0
X-Trace:	newsg3.svr.pol.co.uk 958685791 2911 62.137.54.79 (18 May 2000 21:36:31 GMT)
NNTP-Posting-Date:	18 May 2000 21:36:31 GMT
X-Complaints-To:	abuse AT theplanet DOT net
X-Newsreader:	Forte Agent 1.7/32.534
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> wrote:

> On Thu, 18 May 2000, Alexei A. Frounze wrote:
> 
> > Btw, I usually connect 2nd and 3rd pins of the serial cable/connector in
> > order to test I/O on a single computer. Could this situation be problematic
> > for BIOS?
> 
> I don't think so, but I'm not really a hardware person.  Anybody?

I don't know about BIOS functions, but only looping pins 2&3 (Tx/Rx)
could definitely lead to different behaviours between programs.  

If some code is looking for a handshake line to be asserted then it
could appear to hang, if some other code ignores the handshake lines
then it will appear to work but could drop bytes.  

Loop-back the handshake lines, DTR-DSR and/or RTS-CTS.  And make sure
you also assert the outgoing handshake lines DTR & RTS.

- Raw text -