From:	"Tim Nicholson" <djgpp_mail AT gizzy DOT co DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Async COM managing
Date:	Sun, 24 Dec 2000 13:37:28 -0000
Organization:	Skyforce avionics Limited
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

Arrr.. I see what the problem is now! I have never tried running another
comms program while the original dos box was still open - Nasty Feature!

It would seem dzcomm is not going to help - The dos box still needs to be
closed before another program can access the port!

I still recommend dzcomm as an easy way of handling comms, but not as a
soloution to this problem - sorry.

Tim


"Tim Nicholson" <Tim AT gizzy DOT co DOT uk> wrote in message
news:004101c06d9c$8ff50860$0201a8c0 AT tim...
> Is that what the problem is?
>
> I perceived the problem as being that once the port had been accessed by
> bioscom(). It could not be released again so that other programs to access
> it. This, I thought, was why syco was asking:
>
> > Can I use another functions able to *OPEN* / init / send / receive
> /*CLOSE*
> > the comm port and leave the things clean on exit ?
>
> Dzcomm will definitely does open, initilise, send, receive and  free up
the
> port for other applications once it has finished with it. It does not
allow
> simultaneous use of the port, but I did think that is was an issue here.
>
> I apologise it I got the wrong end or the thread!
>
> Merry Christmas
>
> Tim Nicholson
>
> ----- Original Message -----
> From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
> Newsgroups: comp.os.msdos.djgpp
> To: "Tim Nicholson" <djgpp_mail AT gizzy DOT co DOT uk>
> Cc: <djgpp AT delorie DOT com>
> Sent: 24 December 2000 06:19
> Subject: Re: Async COM managing
>
>
> >
> > On Sat, 23 Dec 2000, Tim Nicholson wrote:
> >
> > > > Is it another way to obtain the expected result, without bioscom() ?
> > > > Can I use another functions able to *OPEN* / init / send / receive /
> > > *CLOSE*
> > > > the com port and leave the things clean on exit ?
> > >
> > > I use a library called dzcomm which is an allegro add-on. It will
allow
> you
> > > to access up to eight com ports and supports shared interrupts. You
can
> > > implicitly open and close ports at any speed that your UART chip
> supports.
> >
> > The problem in this thread was that using a COM port from a DOS box
would
> > disallow other (DOS?) programs running on Windows from accessing the
> > port.  Those other programs are not DJGPP programs and were certainly
not
> > written using DZComm.
> >
> > AFAIK, this is Windows' ``feature'': when a DOS program accesses a COM
> > port, Windows makes it unavailable to other DOS boxes.  This seems to be
> > Microsoft's way to ``virtualize'' the port.
> >
> > Are you saying that you tried this configuration, and DZComm somehow
> > avoids the problem of making the COM port appear to be busy to other DOS
> > boxes?  If so, the way to do that should be seen by studying the DZComm
> > sources.
>

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