Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!ginosko!usc!rutgers!cscnj!paul
From: paul@cscnj.csc.COM (Paul Moody)
Newsgroups: comp.windows.ms
Subject: Re: Interrupt driven I/O under MS-Windows
Summary: Fixed is not Fixed.
Message-ID: <423@cscnj.csc.COM>
Date: 19 Oct 89 13:50:07 GMT
References: <273@ssp7.idca.tds.philips.nl>
Organization: Computer Sciences Corp., Piscataway NJ
Lines: 19

In article <273@ssp7.idca.tds.philips.nl>, bontekoe@idca.tds.PHILIPS.nl (M. Bontekoe) writes:
> We are trying to build a terminal emulation program, which uses interrupt driven
> I/O, running under MS-Windows.
> The source code is ported to MS-Windows and the code segment, containing the 
> asynchronous communication routines, is defined as a FIXED code segment. But
> it doesn't work.

Fixed segments in windows 2.x are not what you think. For windows/286
it is possible to get a real fixed segment, one that does not swap.
For windows/386 this is impossible. Windows maintains an arbitrary
cutoff point above which fixed segments are swapable into lim memory.
Unless you use a fixed dll segment for the interupt code, you will
have trouble getting your code below this line. For windows/386 this
cannot be garunteed.

-- 
Paul Moody			UUCP: rutgers!cscnj!paul 
Computer Sciences Corporation
# the opinions expressed are entirely imaginary			#