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From: alderaan@tubopal.UUCP (Thomas Cervera)
Newsgroups: comp.sys.atari.st
Subject: Re: Multitasking on the ST
Message-ID: <675@opal.tubopal.UUCP>
Date: 11 Aug 89 11:54:37 GMT
References: <8908021826.AA05333@ucbvax.Berkeley.EDU> <15627@watdragon.waterloo.edu> <652@opal.tubopal.UUCP> <471@tw-rnd.SanDiego.NCR.COM> <1066@philmds.UUCP>
Reply-To: alderaan@tubopal.UUCP (Thomas Cervera)
Organization: Technical University of Berlin, Germany
Lines: 26

In article <1066@philmds.UUCP> leo@philmds.UUCP (Leo de Wit) writes:
>In article <471@tw-rnd.SanDiego.NCR.COM> johnl@tw-rnd.SanDiego.NCR.COM (John Lindwall) writes:
>[...] In the current situation it is just as well feasible for
>instance by an application program to thrash the space of the shell it
>was invoked by. So if you insist on security, you should insist on it
>right now already.

  Absolutely correct. But using a multi-tasking system this problem will
multiply.

>An MMU alone probably won't hack it; you will probably want a 680x0
>(x >= 1) to be able to page in new memory (a 68000 doesn't maintain
>enough internal information to be able to restore correctly from a
>BUSERR).

  But isn't there any software solution to that ? (I'm looking on primitive
MMU versions on PDPs where the operating system does a part of context-
saving work on failed EMT or TRAP recovery). The LSI11 processors are very
much like the M68k family. Or is this really impossible on 680x0 ? (Remember,
I'm only a dumb physicist :-) )

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