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From: seanf@sco.COM (Sean Fagan)
Newsgroups: comp.arch,comp.os.misc
Subject: Re: Macintosh OS
Message-ID: <6479@scolex.sco.COM>
Date: 3 Jun 90 23:59:20 GMT
References: <1990May30.230248.6200@Neon.Stanford.EDU> <1935@key.COM> <30273@ut-emx.UUCP> <76700207@p.cs.uiuc.edu> <402@newave.UUCP> <1990Jun2.132847.14292@oracle.com>
Sender: news@sco.COM
Reply-To: seanf@sco.COM (Sean Fagan)
Followup-To: comp.os.misc
Organization: The Santa Cruz Operation, Inc.
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(Note, once again, the followup line.)
From: philip@Kermit.Stanford.EDU (Philip Machanick)
> This "is the Mac OS an OS" line seems to assume that an OS _only_ defines
> multitasking. 

Ok, how about this:  a single-tasking "OS" is a true OS if a program written
for it can be moved to a multi-tasking version of said OS without breaking
in anyway.  That is, if it worked before, it should work now.

I don't believe the Mac does this properly, and that's why I think of it as
a non-OS.  It would be possible, I imagine, to have a "true" MacOS, that
multitasked, and trapped each and every trap, decided what should be done
about it, and then continued the process (for example, doing a bunch of
windows on the screen by trapping screen writes, and then only showing a
certain portion of the "screen" in the window).  But I would, I think,
consider that an emulation package, a la DOS-under-unix.

(I'm not sure whether things like dereferencing NULL, which would probably
be a bug [but not necessarily!  The design could depend on it!], causing a
fatal exception of some short should count when going single-user to
multi-user.)

-- 
-----------------+
Sean Eric Fagan  | "It's a pity the universe doesn't use [a] segmented 
seanf@sco.COM    |  architecture with a protected mode."
uunet!sco!seanf  |         -- Rich Cook, _Wizard's Bane_
(408) 458-1422   | Any opinions expressed are my own, not my employers'.