Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!samsung!munnari.oz.au!sirius.ucs.adelaide.edu.au!augean!sibyl!ian
From: ian@sibyl.eleceng.ua.OZ (Ian Dall)
Newsgroups: comp.arch
Subject: Re: Personal OS
Message-ID: <643@sibyl.eleceng.ua.OZ>
Date: 28 May 90 03:47:20 GMT
References: <402@newave.UUCP> <3300131@m.cs.uiuc.edu> <9437@pt.cs.cmu.edu> <36849@think.Think.COM>
Reply-To: ian@sibyl.OZ (Ian Dall)
Organization: Engineering, Uni of Adelaide, Australia
Lines: 42

In article <36849@think.Think.COM> barmar@nugodot.think.com (Barry Margolin) writes:
>
>Actually, one of the best reasons for a single address space is to simplify
>sharing of data between applications, which promotes integrated software.

"Forces", I would have said.

>warning database, etc.  It's true that integrated software can be written
>when the applications have walls between them, but it's harder and rarely
>very extensible.  A protocol has to be provided, and you are usually
>restricted to the forms of communication that are preconceived by the
>designers; if all the applications are designed together this may be good
>enough, but if they have differing heritages you may be out of luck.

If you are using a shared address space as your means of IPC you are
even more out of luck if the applications are not designed together.

There are many "proofs of existance" to show that a single shared
address space for OS and processes can work. That is not to say that
it is a desirable environment. Many people (myself included) use a
multiuser operating system predominantly with only one active user. I
cannot count the number of times I have had a process die with a
SIGSEGV. Count each of those as a probable system crash. No thanks! I
have 34 processes running on this machine at the moment and I am the
only user. Some of those (esp emacs), have some state dependent on
what I am currently doing. It would be a major inconcenience to loose
that state every time I try and debug a program.

Even running "debugged" official applications ("MacWrite" etc), I have
seen Macs get into a state where they have to be reset. Ditto with
MSDOS machines. The rapid reboot which was quoted as being necessary
in a single user operating system is due to the frequency of the crashes
in such a system.

Of course, processes get into "stuck" states on a multi-tasking OS as
well.  The difference is that you can normally recover with only the
death of that one process.


-- 
Ian Dall     life (n). A sexually transmitted disease which afflicts
                       some people more severely than others.