Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!zaphod.mps.ohio-state.edu!mips!dimacs.rutgers.edu!rutgers!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: A3000 DATA Cache
Message-ID: <21999@cbmvax.commodore.com>
Date: 29 May 91 16:05:43 GMT
References: <1991May26.091925.20814@news.iastate.edu>
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Distribution: na
Organization: Commodore, West Chester, PA
Lines: 24

In article <1991May26.091925.20814@news.iastate.edu> skank@iastate.edu (Skank George L) writes:

>Hello again.  I've noticed on my 3000 that under 2.02 the data cache on
>the 68030 defaults to off when the machine boots up.  I assume that there
>is a good reason for this.  Is it ever safe to turn it on?  I've read
>conflicting reports about it on this group.  

Under 2.02, it's supposed to default to 

	(INST: CACHE BURST) (DATA: CACHE NOBURST)

In SetCPU's words.  You can, in any case, turn data cache/burst on and off at
will.  The software folks have experimentally determined that data bursting
doesn't really help AmigaOS programs, except perhaps some small benchmarks.

>Secondly, what sort of write-back policy does the data cache use (is this a 
>problem)?  Just curious.

The 68030's data cache is write-through.  The 68040 offers the choice of write
through or copyback.  
-- 
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.