Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!batcomputer!caen!sdd.hp.com!wuarchive!uunet!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: AMIGA
Message-ID: <21401@cbmvax.commodore.com>
Date: 8 May 91 19:47:44 GMT
References: <1991Jan10.194127.20625@rice.edu> <17564@cbmvax.commodore.com> <1991Jan15.015644.24380@rice.edu> <1991Jan15.024807.25384@mintaka.lcs.mit.edu> <=-bG-!+=1@cs.psu.edu> <5fDh02JY072Q01@JUTS.ccc.amdahl.com> <1991May6.193235.27330@leland.Stanford.EDU> <48628@ut
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Distribution: usa
Organization: Commodore, West Chester, PA
Lines: 44

In article <48628@ut-emx.uucp> awessels@ccwf.cc.utexas.edu (Allen Wessels) writes:
>In article <1991May6.193235.27330@leland.Stanford.EDU> bard@jessica.stanford.edu (David Hopper) writes:

>>Okay, now *everybody* sing:  WHY IS THIS?  'Cause the '040 boards for ANY
>>Mac will require all that glue, cache, and ram business on the board.
>>It's CPU slot isn't the full 40-whatever pins it takes to interface an '040.

>I don't know how many pins the '040 will require, but my SE/30 has a 120 pin
>Direct Slot.  The IIsi has basically the same slot (or at the very least can
>get adapted to it.)

The real question isn't "how many pins", but "which pins".  I'm not entirely
sure what Mac Processor Direct Slots look like, or what they're for (other
than "Expansion" on machines without NuBus).  There are really several "levels"
of support such a slot could provide:

	Level	Name			Examples
	  1	Slave only		None, on the Amiga at least
	  2	DMA & Slave		Zorro bus on the Amiga
	  3	Coprocessor		A2000 Coprocessor Slot
	  4	Better Coprocessor	A3000 Coprocessor Slot

As it says, this first level supports only slave devices, like maybe a display
card, but doesn't allow any DMA.  Level 2 allows DMA, but is insufficient to
completely take over the system from some main CPU.  Level 3 allows the main
CPU to be completely overridden, which means it needs [a] a mechanism to take
over from the main CPU and [b] all the signals necessary to run in that main
CPU's stead.  Level 4 is just a nicer version of level 3.  The A3000 
coprocessor slot allows the coprocessor CPU to, for example, supply the clocks
to the motherboard, rather than slave to them as with most of this kind of
interface.  It provides lots of signals, more than either the CPU or the 
general purpose expansion bus generally get.

>The reason the Mac '040 upgrades will cost about $2k is that people will be
>willing to pay that much for them.  

That's certainly the bottom line.  If you think can get it, you probably will 
try.  If you're the only game in town on something, and it's desirable, you
charge much more than you could in light of competition.  

-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
      "That's me in the corner, that's me in the spotlight" -R.E.M.