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From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: 68030 options.
Message-ID: <19871@cbmvax.commodore.com>
Date: 14 Mar 91 21:17:26 GMT
References: <18cfc42d.ARN0f05@cbmami.UUCP>
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 26

In article <18cfc42d.ARN0f05@cbmami.UUCP> jason@cbmami.UUCP writes:
>What options do most 68030 users normally use.  I have an A2630 and
>typically run with INST CACHE ON, and DATA CACHE OFF, is it pretty safe to
>run with both CACHE's on?  Is this the same situation with the GVP boards?

Assuming the board was designed with proper cache support, you should never
have any problem turning on both caches and both cache burst enables on any
68030 system.  The one thing to watch for is a _potential_ problem with 
caches and DMA devices.  The small 68030 caches make the chances of a real
problem minimal, but it is technically possible for the 68030 to access 
stale data in either cache after a DMA transfer.  The A2091 software will
actually flush the cache after an I/O operation completes, but in general,
this isn't anything to greatly worry about.  Whether or not it supports burst,
all 68030 memory systems are required to work properly when burst is enabled.
Testing in our software department has indicated that the burst mode helps 
out for the I-Cache, but doesn't for the D-Cache.  Your mileage may, of course,
vary, but keep in mind that typical small benchmark programs are not 
represenative of actual AmigaOS code/data behavior.

>Jason Goldberg				UUCP: ucsd!serene!cbmami!jason


-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
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	"What works for me might work for you"	-Jimmy Buffett