Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!uakari.primate.wisc.edu!ames!ucsd!rutgers!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: The Atari TT
Message-ID: <7824@cbmvax.UUCP>
Date: 5 Sep 89 16:48:13 GMT
References: <5251@ucdavis.ucdavis.edu>
Distribution: na
Organization: Commodore Technology, West Chester, PA
Lines: 36

in article <5251@ucdavis.ucdavis.edu>, kuan@iris.ucdavis.edu (Francisco Kuan) says:

> Can that Atari TT MULTITASK??

Any '030 based system can multitask.  Some '030 systems are designed for this
better than others.

The question to ask is, can TOS 1.whatever multitask.  The answer is most
likely no; TOS, GEMDOS, MS-DOS, and the Macintosh OS weren't designed to 
multitask.  The main problem with such systems is [1] operating system 
routines that aren't re-entrant, and [2] global task information (eg, when 
I'm thinking of an OS with only 1 task, why would I place the information 
this execution stream depends upon in a dynamic structure that can be easily 
swapped during a context switch).  Another problem in such systems are the 
lack of resource locking (eg, assuming you manage to get two tasks running, 
the OS can't keep both from writing simultaneously to the same file, or has 
no resource manager for simultaneous access to the same hardware).  And 
even if you get past that point, you still don't have a real multitasking
OS -- there's no IPC, for instance.

Taking the Mac OS as a model, some of these thing might be worked around in
a future TOS, depending on how well it was written (Mac software tends to
be pretty good; I'd expect TOS is in much worse shape).  Apple's Multifinder
kinda-sorta multitasks -- they get around reentrancy issues by making tasks
only swap during a certain function call, never while in an arbitrary OS
call.  This tends to make the multitasking something a programmer must worry
about far more than under AmigaOS or UNIX, and only as functional as the
least well-written program you're trying to run.  

On the other hand, you'd presume that an Atari TT machine, like other '030
machines, would run UNIX just fine.

-- 
Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
                    Too much of everything is just enough