Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!elroy.jpl.nasa.gov!lll-winken!uunet!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: A3000, 68040
Message-ID: <11290@cbmvax.commodore.com>
Date: 3 May 90 17:57:08 GMT
References: <1990May3.043218.15590@cec1.wustl.edu>
Reply-To: daveh@cbmvax (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 46

In article <1990May3.043218.15590@cec1.wustl.edu> amc4919@cec2.UUCP (Adam Michael Costello) writes:
>If you use that socket in the 3000 to upgrade to a 68040, is it still bound to
>run at 25MHz (or 16MHz, as the case may be)?  

No.  The A3000 motherboard can only be run at either 16MHz or 25MHz, and a 
Coprocessor slot card can use the motherboard clocks or, alternately, supply
its own.  If you want an add-in that goes faster than 25MHz, no problem, only
it'll have have keep the faster cycles on the Coprocessor slot only.  Much
like the way the A2630 does things in a 2000.  That's really not a big deal;
there's not much around these days, other than cache memory, that can even
keep up with a 25MHz 68030, much less a faster '030 or an '040.

>In any case, if you upgrade to the 68040, does it matter whether the 3000 was 
>16 or 25?

Depends on the design of the 68040 Coprocessor card, but it doesn't have to
matter -- such a card could run the A3000 main bus at 25MHz, regardless of
the on-board CPU speed.

>Can the upgrade be done now, or are there things we have to wait for?  

I guess you have to wait for a 68040 Coprocessor card.  No one's announced
one yet.

>The 68040 is a 64-bit processor (internally, 32 bit data bus though), right?  

Yes and no.  It's a 32 bit Harvard architecture machine, like the 68030 only
better.  At any given time you may have two simultaneous 32 bit transfers going
on the separate I and D buses.  Since 32 + 32 = 64, some call that a 64 bit
architecture.  I wouldn't call something 64 bit unless it had 64 bit registers
and 64 bit operations on such registers.  Which I guess does in part exist on
the 68040, since math operations and registers are actually 80 bits wide,
internally.

>What else does the '40 have over the '30?

Real big, fast physical caches, very clever pipelining, some hardwired
instructions, on-chip math.  That's the basic feature list.

>AMC


-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
	"I have been given the freedom to do as I see fit" -REM