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From: dmurdoch@watstat.waterloo.edu (Duncan Murdoch)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Writing a device driver in TP
Message-ID: <1991May30.022659.23896@maytag.waterloo.edu>
Date: 30 May 91 02:26:59 GMT
References: <1991May29.140429.11384@maytag.waterloo.edu> <1991May30.002543.13967@midway.uchicago.edu>
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Organization: University of Waterloo
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In article <1991May30.002543.13967@midway.uchicago.edu> valley@gsbsun.uchicago.edu (Doug Dougherty) writes:
>This has nothing to do with the original post, but...
>
>dmurdoch@watstat.waterloo.edu (Duncan Murdoch) writes:
>
>> - They [.EXE format device drivers] work in MSDOS, but not PCDOS,
>	because the .EXE loader is part of COMMAND.COM in PCDOS.
>really??? ---------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>> - They only work in version 3 or higher.
>
>That's interesting.  Does this mean that you can't exec() a .EXE file
>directly (from another program) in PC/DOS?  (I.e., that you would have
>to run it via system() ?)

I haven't tested either claim, but the first one is kind of hard to believe.
In fact, my PC DOS 3.1 tech ref manual specifically mentions that .EXE format
device drivers are allowed, though it doesn't say much about them.  However,
I have heard it before, so the tech ref could be wrong.

As to the exec() question:  the version I heard was that the loader was part
of the resident part of COMMAND.COM, so it'll handle the EXEC service.
I'd love to here from someone who uses PC DOS whether this limitation is real
or just folklore.

Duncan Murdoch
dmurdoch@watstat.waterloo.edu