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From: valentin@cbmvax.commodore.com (Valentin Pepelea)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: A3000 CPU slot
Message-ID: <11447@cbmvax.commodore.com>
Date: 9 May 90 03:09:16 GMT
References: <11207@cbmvax.commodore.com> <11378@cbmvax.commodore.com> <11413@cbmvax.commodore.com> <29VY02MJa5P.01@amdahl.uts.amdahl.com>
Reply-To: valentin@cbmvax (Valentin Pepelea)
Distribution: comp
Organization: Commodore, West Chester, PA
Lines: 58

In article <29VY02MJa5P.01@amdahl.uts.amdahl.com> kim@uts.amdahl.com
(Kim E. DeVaughn) writes:
>
>Well ... you did say you thought multiprocessing would be "a snap", and I
>can't see how it'd be *easy* without atomic Test-and-Set capabilities.

Semaphores can be implemented using three flags, for two communicating tasks,
plus one flag for each additional task (processor). This is well explained in
any good OS textbook.

>I'm pleased to see that Zorro-III is supporting this, but couldn't this pose
>a problem when s/w that does this is run on a Zorro-II machine, where the co-
>processor chips can sneak-in in the middle of the read-modify-write cycle?

Devellopers of multi-processor boards will probably choose to produce Zorro III
cards only.

>So we'll have to depend on such applications and/or AmigaOS to be "well-
>behaved" and ask the "other" CPU(s) to flush, if the access is going to be
>made to a memory location that could be shared?  Is that correct?

No support for multi-processing has been put in the OS yet. So data handshaking
models still have to be thought out. Shared areas of memory are likely to be
either non-cacheable, or special data transferring functions will take care
of cache coherency.

>Speaking of caches, does the A3000's SCSI-driver "do the right thing" and
>flush the data cache(s), so one can run with the D-cache enabled without
>worry now?

To my knowledge, yes.

>All this foresight sounds very positive for the future.  Good job y'all!!!
>
>"Amiga ... the 1st *afordable* multiprocessing machine.  While other's are
> struggling to but implement multitasking!" ... I love it!   :-)

Whoa! Wait a minute! We don't have it yet. Nobody has yet made a multi-
processing board. In fact, nobody has yet made a Zorro III board!

>> Never heard of the "poof!" group, but you all now Capt. Crunch, don't you?
>
>Hmmmmm ... "poof!" was the equivalent to "It's in there!" during the 1.2->1.3
>upgrade timeframe (possibly before that).  I think it was Dave Haynie, or maybe
>Andy Finkel who I first noticed using it.   As for "Crunch" ... did he ever
>get his legal difficulties resolved ... anyone know ...?

I guess we are referring to different Captain Crunches. The term was first used
to my knowledge after I made an appeal for a multi cereal card, hoping Kellogs
just might...  But they did not. I guess they did not see how multi cereal ports
can mix with 5V power lines to produce snap, crackles and pops.

Valentin
-- 
The Goddess of democracy? "The tyrants     Name:    Valentin Pepelea
may distroy a statue,  but they cannot     Phone:   (215) 431-9327
kill a god."                               UseNet:  cbmvax!valentin@uunet.uu.net
             - Ancient Chinese Proverb     Claimer: I not Commodore spokesman be