[comp.sys.mac.system] Preemtive/Cooperative multitasking

mings@comix.cs.uoregon.edu (Ming Yau So) (03/29/91)

In article <0B010004.4k8s8a@outpost.UUCP> peirce@outpost.UUCP writes:
>In article <91085.161852EHYOUNK@MTUS5.BITNET>, EHYOUNK@MTUS5.BITNET writes:
>> 
>> I completly agree with the statement that Mac OS should have prementive
>> multitasking.. Multifinder is a joke, they is no way to download from a modem
>> while running another app. Here are some other problems.
>
>What comm program are you using?  All the ones I've used allow this
>without any trouble at all.  Even those who don't like MultiFinder
>say things like "besides downloading, what's it good for..."
>
>If your comm program doesn't do this switch to one that does, there
>are many to choose from.

   [ stuff deleted ]

I am not the original poster, but here is an example.  Use any of your
favorite comm. software to download a file, then switch to Finder, and
copy a floppy.  What do you think will happen ?  The download fails !

Don't get me wrong, I like my Mac and MF (at least MF gives you some degree
of mulyitasking which is totally lacking in MS-DOS).  However, I feel
preemtive multitasking is better than cooperative multitasking.  It is true
that a foregroung task maybe very irresponsive when you are using a public
machine, because you cannot assign a higher priority to the foreground job.
But the situation is differet on your Mac, because (most of the time) you are
the only user of your Mac, you are the system adminitrator of your Mac !  So
you can assign the priorities to the jobs as you like.  Therefore I don't
think preemtive multitasking would bring any inconvenience to a Mac user,
indeed, it gives the user more controls.

Well, this is just my personal opinion, please no flame.
-- 
___________________________________________________________________________
   Ming Yau So                        | Disclaimer needs to be repaired !!
   Internet: mings@cs.uoregon.edu     |      >>>SCUD>>>   (disclaimer) 
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doner@henri.ucsb.edu (John Doner) (03/30/91)

In article <1991Mar29.020730.15872@cs.uoregon.edu> mings@comix.cs.uoregon.edu (Ming Yau So) writes:
=In article <0B010004.4k8s8a@outpost.UUCP> peirce@outpost.UUCP writes:
=>In article <91085.161852EHYOUNK@MTUS5.BITNET>, EHYOUNK@MTUS5.BITNET writes:
=>> 
=>> I completly agree with the statement that Mac OS should have prementive
=>> multitasking.. Multifinder is a joke, they is no way to download from a modem
=>> while running another app. Here are some other problems.
...
=I am not the original poster, but here is an example.  Use any of your
=favorite comm. software to download a file, then switch to Finder, and
=copy a floppy.  What do you think will happen ?  The download fails !
=...  Therefore I don't
=think preemtive multitasking would bring any inconvenience to a Mac user,
=indeed, it gives the user more controls.

Preemptive multitasking is pretty much irrelevant to the situation
described.  The reason the download fails is that for PHYSICAL reasons
the disk driver must disable interrupts for rather long periods while
disk operations are in progress.  Those reasons will still exist
whether or not your operating system offers preemptive multitasking.

The cure for the problem is DMA, not preemptive multitasking---the i/o
hardware needs to be able to operate without much cpu intervention.

John E. Doner	doner@henri.ucsb.edu	(805)893-3941
Dept. Mathematics, UCSB, Santa Barbara, CA 93106

mel@fleet.UUCP (mel) (04/01/91)

Bdd
B
>The cure for the problem is DMA, not preemptive multitasking---the i/o
>hardware needs to be able to operate without much cpu intervention.
>
>John E. Doner	doner@henri.ucsb.edu	(805)893-3941
>Dept. Mathematics, UCSB, Santa Barbara, CA 93106

That's a good point.  And why hasn't Apple been able to get DMA working?
The FX supposedly has the capability but no version of the operating
system supports it EXCEPT AUX.  And rumors have it the new '040 CPU's
won't support DMA at all. (Nor does 7.0)

What is going on at Apple in regards to DMA?  Can't someone come forward to
explain why they keep falling down in this one area?

Mel Shear
!rex!fleet!mel

david_islander_hughes@cup.portal.com (04/02/91)

I use White Knight 11.x EVERY DAY, along with other weird comms
problems (like downloading weather faxes with my McRatt software and
mail from Portal while doing page layout work.

Thw WK download is fine, the radio downloads are fine - all under multifinder.
My setup:
CI w 8 megs hard memory (13.32 megs with Virtual 2.0)
130 Meg Jasmine HD
2400 baud vanilla modem
PK 232 Radio TNC

peirce@outpost.UUCP (Michael Peirce) (04/03/91)

In article <12@fleet.UUCP>, mel@fleet.UUCP (mel) writes:
> 
> Bdd
> B
> >The cure for the problem is DMA, not preemptive multitasking---the i/o
> >hardware needs to be able to operate without much cpu intervention.
> >
> >John E. Doner	doner@henri.ucsb.edu	(805)893-3941
> >Dept. Mathematics, UCSB, Santa Barbara, CA 93106
> 
> That's a good point.  And why hasn't Apple been able to get DMA working?
> The FX supposedly has the capability but no version of the operating
> system supports it EXCEPT AUX.  And rumors have it the new '040 CPU's
> won't support DMA at all. (Nor does 7.0)
> 
> What is going on at Apple in regards to DMA?  Can't someone come forward to
> explain why they keep falling down in this one area?

The problem is their SCSI software.  It's, well, not the best code
ever written by the boys (and girls) in Cupertino.

System 7 was suppose to have a new SCSI manager, but it got pushed
back until a later release.  I'm hoping it comes out soon after 7.0.

-- michael

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