Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uunet!tut.cis.ohio-state.edu!pt.cs.cmu.edu!b.gp.cs.cmu.edu!Ralf.Brown@B.GP.CS.CMU.EDU
From: Ralf.Brown@B.GP.CS.CMU.EDU
Newsgroups: comp.sys.ibm.pc
Subject: Re: What is 4DOS?
Message-ID: <25a89a30@ralf>
Date: 8 Jan 90 12:48:32 GMT
Sender: ralf@b.gp.cs.cmu.edu
Organization: Carnegie Mellon University School of Computer Science
Lines: 25
In-Reply-To: <111700191@uxa.cso.uiuc.edu>

In article <111700191@uxa.cso.uiuc.edu>, lmhg0369@uxa.cso.uiuc.edu wrote:
}I gave the docs a cursory look and installed it on my AT clone.  One thing
}disconcerting is that the first time I do a 'dir' it takes at least a second or
}two just sitting there before it spits anything out to the screen.  Subsequent
}dirs for the same directory occur at a speed I consider reasonable.
}
}Is this performance normal?

4DOS reads the entire directory before displaying anything (so that it can sort
on the names, or size, or whatever you tell it).  The first time you look at a
directory, MSDOS has to read the disk; subsequent times, the directory is
(usually) still in the disk buffers, which speeds up the process considerably.
Also note that the first directory taken on any given disk requires that MSDOS
read the entire FAT to determine the disk free space; COMMAND.COM will show
the entire directory and then pause while MSDOS scans the FAT to count up the
free space.  4DOS probably asks for the free space before displaying anything.

--
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"How to Prove It" by Dana Angluin              Disclaimer? I claimed something?
17. proof by mutual reference:
    In reference A, Theorem 5 is said to follow from Theorem 3 in reference B,
    which is shown to follow from Corollary 6.2 in reference C, which is an
    easy consequence of Theorem 5 in reference A.