Path: utzoo!attcan!uunet!mcvax!unido!tub!tubopal!alderaan
From: alderaan@tubopal.UUCP (Thomas Cervera)
Newsgroups: comp.sys.atari.st
Subject: Re: Re^2: Multitasking on the ST
Message-ID: <677@opal.tubopal.UUCP>
Date: 13 Aug 89 11:22:51 GMT
References: <8908021826.AA05333@ucbvax.Berkeley.EDU> <15627@watdragon.waterloo.edu> <652@opal.tubopal.UUCP> <415@nixpbe.UUCP>
Reply-To: alderaan@tubopal.UUCP (Thomas Cervera)
Organization: Technical University of Berlin, Germany
Lines: 40

In article <415@nixpbe.UUCP> mboen@nixpbe.UUCP (Martin Boening) writes:
>What's all this about NEEDING memory segmentation for Multitasking. You can
>have Multitasking without memory segmentation. (Of course memory segmentation
>helps a lot). Just look at several multitasking OSs for the ST, all running
>without a REAL MMU: OS-9/68000, IDRIS, RTOS-UH/Pearl, MINIX-ST, Xinu,
>(what else ?).
> [...]
>I hope this convinces everybody that multitasking is possible (even if not
>feasible due to lack of speed) on the ST.

  {:-(

  Encore une fois:
  Multi tasking is possible but USELESS for every-day operation on a machine
where every little bullsh*t program can trash important memory. You definetely
CANNOT shrink a system's kernel PLUS working variables completely into 2048
bytes. BUT THAT'S ALL PROTECTED MEMORY YOU HAVE ON AN ST. Oh, sure, you could
execute what's in the hardware registers.
  I don't want to think about wasted time during software debugging on a
machine where ANY program can produce unpredictable and perhaps unreproductable
reactions of ANY program running on it (INCLUDING THE OPERATING SYSTEM ITSELF)
if it's not coded correctly. (Maybe your printer daemon crashes the system
every time you print more than 42 asterisks).
  It is not neccessary at all that YOU are the source of this behaviour, some-
one else who has written a program currently running in your system's background
could be the cause ! Perhaps YOU WILL NEVER KNOW !
  If you have an MMU and if your 'crash exception handler' is working correctly,
only the nasty program will die WITHOUT affecting others. Because of that you
can exactly determine what's going wrong there.

  Of course, this is not only relevant for multi tasking systems on the ST but
for all multi-program environments on this machine (including TOS). BUT it's
a matter of fact, that multi tasking means multiplying the probabilty of crazy
system behaviour !

-- 
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