Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!bcm!dimacs.rutgers.edu!rutgers!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: SetCPU - what can I do with it?
Keywords: SetCPU, A3000, uses
Message-ID: <19293@cbmvax.commodore.com>
Date: 25 Feb 91 18:39:52 GMT
References: <1991Feb23.224056.28061@cbnewsj.att.com>
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Distribution: na
Organization: Commodore, West Chester, PA
Lines: 36

In article <1991Feb23.224056.28061@cbnewsj.att.com> vrr@cbnewsj.att.com (veenu.r.rashid) writes:

>I just got a copy of SetCPU, the utility to change '030
>parameters.  I just got my A3000 recently, and I do not
>know what the cache or MMU does, other than change the
>performance if burst mode is on or off.  

You don't really need SetCPU with the A3000.  The 2.0 Operating System sets up
the I and D caches the way they should be set.  If you are using SetCPU with
the A3000, make sure that you have V1.6, since V1.5 and earlier were written
before 2.0 knew how to handle cache parameters and, as a result, are not
effective in modifying the cache parameters under 2.0.

>Can someone tell me how I can use this program?  I tried 'SetCPU FASTROM'
>or something like that, but it came back with:
>Error: Alien MMU setup prevents FASTROM

My first question might be, if you don't know what FASTROM does, why do you
care if it works or not?  The documentation should come with SetCPU.

In any case, SetCPU is telling you that some other agent, in this case the 
A3000's SuperKickStart, is using the MMU.  The "FASTROM" option of SetCPU 
normally copies the ROM contents of a system into a 32 bit RAM buffer, then 
uses the MMU to make that appear in place of the ROM.  On an A2500, which has 
a 7.16MHz, 16 bit, 68000 bus ROM, this can make a noticable speed improvement.
The A3000 essentially has this all built-in.  SetCPU won't attempt to modify 
an MMU setup that it didn't create.  Since it has no way of knowing which 
program created the MMU setup other than itself, it'll report "ALIENMMU" for 
any MMU setup it didn't create.

>Veenu Rashid

-- 
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