Date: Thu, 5 Oct 2000 17:43:56 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To: Petr Maxa <maxa AT sse-za DOT sk>
cc: djgpp AT delorie DOT com
Subject: Re: Protected mode access to file system
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On Thu, 5 Oct 2000, Petr Maxa wrote:

> OK, but I am still not satisfied completely because my program is making a
> lot serial communications on several ports (from 4 to 10 ports are used).
> For that communications I set-up protected mode isr. But I am afraid that
> when I write data to disk there might be some collision and overwhelm during
> the same mode switching as was stated above. I am also suspicious that due
> to using real mode services during compilation, the compilation time of
> djgpp is slow.

Experience shows that, unless your application writes lots of data 
(megabytes of it), the penalty of the mode switch incurred by disk I/O is 
negligible, provided that you don't do stupid things like writing one 
byte at a time.  For some discussion of relevant details, see sections 
14.1 and 14.4 in the DJGPP FAQ list.

> So there is a question. Is not anywhere developed an library which uses a
> only 32 protected mode to files access (open, close, read, write, seek ...)
> which would run under DOS (not DOS box under W9X).

If you bypass DOS for file I/O, there's no much sense in using DOS at 
all.