Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!apple!decwrl!waikato.ac.nz!bwc
From: bwc@waikato.ac.nz (Ug!)
Newsgroups: comp.sys.acorn
Subject: Re: 'operation systems'
Message-ID: <1991Jun28.083032.4097@waikato.ac.nz>
Date: 27 Jun 91 20:30:32 GMT
References: <1991Jun27.191439.28073@rusmv1.rus.uni-stuttgart.de>
Organization: Voonyercity fo Kaiwatoe
Lines: 36

MUFTI writes:
> Subjects: ... other Operation system as RISCOS
> 
>  Cause currently RISCOS has a lack of modern features ( all other 
>  operation systems (accept the old operationsystems CPM,MSDOS,GEM and 
>  AppleIIdos) are better in this cases ) like timesheduled multitasking and
>  we need a better Operationsystem ( or a rebuild of main parts of riscos to
>  allow such things ).
>  I think the very old UNIX version II (=MINIX) is such a operation system,
>  but is there still someone, who work to implement it ?
>  I heard nothing in last 2-3 month from Martin Patzel or from Albert Coelmans.

As operating systems go, RiscOS ain't half bad.  Okay, it doesn't support
preemptive tasking, but then, that's not necessarily a problem.  With an
environment such as RiscOS, it provides all that's really necessary - interrupt
driven routines for background operations, and cooperative tasking, which has
lower overheads, and is generally more suitable to windowing software anyway.

Threads (small processes) would be nice, but they could be supported within
a single task (where you want them anyway) by an appropriate language.
Modula-2 has coroutines, and you can also do them in C if you're really keen.
Of course, there's no Modula-2 compiler for the Archimedes...  come back Arthur!
All is forgiven!

I don't think demand paging is the way to go for virtual memory on the
Archimedes (see previous comments) - task swapping (controlled by the scheduler)
would be more appropriate, and in the Archimedes case (page size of 64K!  Gak!)
probably faster...  sad fact of life.

Unix version (release?) 2 = MINIX?  Oh yeah, new one on me!  Acorn already has
a good implementation of Unix for the Archimedes architecture - RiscIX.  I mean,
it's POSIX compliant (so I've been told), BSD and System V compatible, and it
runs Motif *fast* (on the R260 of course).  Of course, Unix is 20 years old...
so if you want a 'modern operation system', are you sure you want Unix?

							Ug!