Path: utzoo!mnetor!uunet!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: 68030 Questions
Message-ID: <3246@cbmvax.UUCP>
Date: 1 Feb 88 22:09:17 GMT
References: <10170@ccicpg.UUCP>
Organization: Commodore Technology, West Chester, PA
Lines: 37

in article <10170@ccicpg.UUCP>, harald@ccicpg.UUCP ( Harald Milne) says:
> In article <3200@cbmvax.UUCP>, daveh@cbmvax.UUCP (Dave Haynie) writes:
>> The '030 running with data cache enabled introduces the most problems.  Still,
>> many of these can be solved in hardware if the designer takes the time;
>> you really do want to use that data cache!

> 	Amen!

> 	The only problem I can imagine at this point, is DMA to FAST ram. 
> Would anybody be silly enough to do this? This will kill the 680x0.

This happens all the time with things like hard disk drives.  It sure does
hurt the 68000's speed, but consider the alternative.  You've got to get
that disk data into memory somehow.  If you make the 68000 go and read it
from an I/O port somewhere, you're running several memory cycles per data
transfer.  I mean, instruction fetch, I/O fetch, instruction fetch, write to
RAM, instruction fetch, test and branch, something like that.  Once a DMA
driven controller is set up (simple, nothing like setting up the blitter),
you have a bus arbitration, then one word transferred by the controller per
memory cycle.  If you're a 68020, you may even run a little from cache after
the arbitration.  So this is much faster than possible without DMA.

> 	I got a sneaky suspicion, that to get a few thousand miles away, you
> were at AmiExpo! Darn.

No, actually, Paradise Island, The Bahamas.

Didn't make AmiExpo.  Woulda been nice too, but I had all this work piled
up here.

> Work: Computer Consoles Inc. (CCI), Advanced Development Group (ADG)
>       Irvine, CA (RISCy business! Home of the CCI POWER 6/32)
> UUCP: uunet!ccicpg!harald
-- 
Dave Haynie  "The B2000 Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {ihnp4|uunet|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
		"I can't relax, 'cause I'm a Boinger!"