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From: cur022%cluster@ukc.ac.uk (Bob Eager)
Newsgroups: comp.os.misc
Subject: Re: What constitutes a good OS?
Message-ID: <21652.27a00592@cluster@ukc.ac.uk>
Date: 25 Jan 91 10:16:49 GMT
References: <42488@nigel.ee.udel.edu> <5461@auspex.auspex.com> <11469@darkstar.ucsc.edu> <5509@auspex.auspex.com>
Organization: Computing Lab, University of Kent at Canterbury, UK.
Lines: 16

In article <5509@auspex.auspex.com>, guy@auspex.auspex.com (Guy Harris) writes:

> VMS is, I think, similar (although I think the ACP was replaced by the
> "extended QIO processor", which isn't a process receiving messages but
> is directly called, for performance reasons), although RMS runs, as I
> remember, in executive rather than user mode.  Dunno if user-mode
> programs can, if they choose, get direct access to the "container" via
> QIOs or not.

Yes, they can. The container layer (RMS) allows an essentially transparent
mode of access, and for higher efficiency one can call the disk driver using
a QIO to obtain direct access to the file at the block level.
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Bob Eager                | University of Kent at Canterbury
                         | +44 227 764000 ext 7589
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