Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: 68030+68040 on A3000: is it possible?
Message-ID: <21305@cbmvax.commodore.com>
Date: 6 May 91 21:18:20 GMT
References: <24561@well.sf.ca.us> <41966@cup.portal.com>
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Distribution: na
Organization: Commodore, West Chester, PA
Lines: 38

In article <41966@cup.portal.com> Fletcher@cup.portal.com (fletcher sullivan segall) writes:

>>Unfortunately, as i understand it the Fast Slot on the A3000 motherboard
>>is a bus master slot - it disables the 030. 

>Your information is incorrect.  The coprocessor slot on the A3000 fully
>supports using both processors simultaneously (this is one of the changes
>from the A2000).  

Neither system permanently disables the corresponding motherboard processor.
Both the A2000 and the A3000 permit a coprocessor device to get on and off
the motherboard bus, allowing the motherboard processor to stay active, thus
the name "coprocessor" slot.  Now, neither motherboard bus is dual ported or 
anything weird like that, they have to share it just as other bus masters share 
the bus, but such sharing is very possible.  The bus arbitration time on the 
A3000 coprocessor slot is much less than that of the A2000 coprocessor slot.
And the 68030 style of bus locking is much easier to deal with than the 68000
kind, which would have been required in any A2000 card that attempted to keep
the 68000 active.

>>Would a crafty hardware firm be able to create a workaround? is it feasible?
>>is it worth the trouble? - it seems a waste to throw out the 7.5 mips the
>>A3000 pumps out...27+ Mips would be screaming....

>I think the 68030 at 25MHz is only about 4.25 (V2,1) MIPS.

MIPS can generally mean whatever you want it to mean, I think the term was
originally coined by Humpty Dumpty.  If you're thinking of DHRYSTONE 2.1, the 
25MHz A3000 usually generates in the neighborhood of 7,000-8,000, depending on 
compiler and various optimizations selected.  

>Fletcher@cup.portal.com


-- 
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.