From: "Peter Remmers" <Peter DOT Remmers AT t-online DOT de>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Async COM managing
Date: Sat, 6 Jan 2001 16:19:37 +0100
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Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> schrieb...

> > I think it's not even too hard, since it's documented in the Win98 DDK.
> > 
> > Windows 98 DDK
> >   Related Driver Documentation
> >     Windows 95 Documentation
> >       Design Guide
> >         Virtual Communications Device Drivers
> >           Virtual Communications Driver
> >             Protected-Mode Application Programming Interface
> 
> Are the values to put into registers documented there in enough detail
> to allow one to write a non-trivial code which uses the COM port?

The documentation is terse. But the PM-API is basically just a wrapper for
the VXD-to-VXD interface of VCOMM, which is documented better.
Constants can be looked up in the header files, ans structures are
declared there, too.
What I don't understand is why pointers are passed as 16:16 and not
16:32? Could that mean buffers have to reside in low DOS memory?

> The problem with this interface is not how to access it---this is
> documented in RBIL---but what data structures to use, how to lay them
> out, and what values to use for some of the flags.  If that is
> documented by Microsoft, then the problem is solved (but then I wonder
> how come it took such a long time for Rich Dawe and friends to find
> the way to make the Wsock2 interface work).

That's because the wsock2 PM-API is NOT documented, as far as I can see
(at least not in the DDK). The DDK documents only the VCOMM PM-API.

Peter