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From: djc@sun.uucp (David J. Cardinal)
Newsgroups: net.micro
Subject: Re: CBM, Z8000, & Unix
Message-ID: <895@sun.uucp>
Date: Mon, 16-Apr-84 18:19:44 EST
Article-I.D.: sun.895
Posted: Mon Apr 16 18:19:44 1984
Date-Received: Tue, 17-Apr-84 08:33:17 EST
References: <70@ssc-vax.UUCP> <437@dual.UUCP>
Organization: Sun Microsystems, Inc.
Lines: 27

UNIX's inability to run on floppy based systems seems to
be related to its need to always touch the disk, and
the lack of a disk cache in low end systems.

(The obvious problem is that the user can screw up the
disk and the cache by swapping floppies).

Data General's MPOS epitomizes a system that is "UNIX-like"
and combines the slowness with an inability to swap disks
without explicit commands (ported from a hard-disk system, typically).

On the other hand, the Quantum Software "QNX" system combines
infrequent and relatively rapid disk access with a rock-solid
file system (mostly due to simplicity).  I don't know the tricks
they have used, as I do not have source, but the result
is a definite step forward in UNIX-like floppy based systems.
(Note that QNX is not UNIX licensed, and is actually a pretty
nifty message-passing kernel emulating UNIX so that people will
buy it.)

Thus the problem seems not to be with UNIX per se, but with
implementations of operating systems developed on hard-disk
systems and then thoughtlessly ported to floppies.

--dave cardinal
	sun!djc