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From: aaw@pyuxss.UUCP (Aaron Werman)
Newsgroups: net.micro,net.research,net.cse
Subject: Re: Should Universities Explore... Re: 'toy OS'
Message-ID: <305@pyuxss.UUCP>
Date: Wed, 4-Apr-84 10:13:34 EST
Article-I.D.: pyuxss.305
Posted: Wed Apr  4 10:13:34 1984
Date-Received: Thu, 5-Apr-84 00:51:19 EST
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Organization: Bell Communications Research, Piscataway N.J.
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[Impenitent, we meet again,]

I have read Per Brinch-Hansens' 'Programming a Personal Computer' or
somesuch. It is an inarticulate users manual for the Edison system,
despite the title. Other than choice of a subset of Pascal for the
Edison language, no Comp. Sci. issues were addressed. Edison is a
minimal toy OS all written in a structured language (although some was
hand compiled rather than interpreted) and might be used for a
Software Engineering or OS course, but only because students could
review (and rewrite components of) the entire code (~10k lines) in one
term.

CP/M and its' look alikes MS-DOS, etc. would not be useful for an OS
course because they are fundamentally jump tables for system routines
rather than OSs. As such they could be used for writing device drivers
(a very common OS application traditionally left out of OS courses
because big OSs don't like switching drivers.) Most OS course material
is not relevant to MS-DOS: e.g. virtual memory, multiprogramming,
multiprocessing, swapping, tasking, device allocation algorithms,
deadlock prevention/detection, job mix... about 95% of the material is
reduced in a single user single task OS to the trivial case. While
these are valuable skills a student will get no feel for tradeoffs,
which are real issue in OS design
			{harpo,houxm,ihnp4}!pyuxss!aaw
			Aaron Werman