Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!osu-cis!killer!elg
From: elg@killer.Dallas.TX.US (Eric Green)
Newsgroups: comp.sys.amiga
Subject: Re: Multiprocessing-Multitasking
Message-ID: <7819@killer.Dallas.TX.US>
Date: 12 Apr 89 01:10:55 GMT
References: <12700@louie.udel.EDU>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 48

in article <12700@louie.udel.EDU>, DAVEA%CERNVM.BITNET@cunyvm.cuny.edu (David Almond) says:
> to burn precious space, is that the though the Amiga is multitaskingfor
> all the reasions you outlined is not fully multitasking beause there
> is no scheduler which controls overall running of tasks. So that it
> would no how much spare capacity exists on each intelligent processing
> device, as it processes, and thus be able to dispatch the next processing
> task in the most efficent manner.

Say WHAAA??? are you SURE that you don't work for BYTE??? (Yes, I know
that you denied it -- but this is typical of Byte misinformation).

The Amiga DOES have a central task scheduler -- what do you think Exec
is? Now, there's a few problems with the Amiga's task scheduler -- it
allows high priority processes to hog all of the CPU without dribbling
any down to low priority processes, in the event that the programmver
of the high priority process puts a wait loop instead of a Wait() call.
But that is irrelevant to the average user (who runs all of his
programs at priority 0, where un-blocked tasks are timesliced
equally), and perfect for real-time work (which is what Exec was
designed for in the first place).

So, while the Amiga's task scheduler isn't of the level of, say, the
Multics task scheduler (which took into account size of program, how
many keys you typed in the last few minutes, and lots of other
esoteric info -- I kid you not), it DOES have one. 

Or perhaps you wanted to say "let other processes run while you're
using the blitter"? Look at the QBlit () routine in graphics.library,
which allows you to queue blitter requests. Or WaitBlit() which puts
your process to sleep while your blitter request is going (thus
letting other programs run). Or.... well, you get the picture.

Or perhaps you wanted to say, "have the disk handler queue requests &
sort them so that the disk drive doesn't gronk"? That has nothing to
do with the multitasking ability of the Amiga -- just with a very
badly designed disk handler (:-().

The Amiga is multitasking. Period. It's the multi-processing part
that's only "semi" (the blitter and copper aren't "real" processors,
but they "sort of" count). And while the internals of the process
scheduler would require work for a multi-processor Amiga, a
shared-memory multi-processor AmigaDOS would work just fine (just as
long as you have write-through caches, & bus-sniffing). 

--
|    // Eric Lee Green              P.O. Box 92191, Lafayette, LA 70509     |
|   //  ..!{ames,decwrl,mit-eddie,osu-cis}!killer!elg     (318)989-9849     |
| \X/            Amiga.  The homestation for the blessed of us.             |