Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!samsung!cs.utexas.edu!rutgers!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: SetCPU and the 2091
Keywords: SetCPU, 2091
Message-ID: <10120@cbmvax.commodore.com>
Date: 12 Mar 90 20:06:28 GMT
References: <11051@june.cs.washington.edu>
Reply-To: daveh@cbmvax (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 28

In article <11051@june.cs.washington.edu> dylan@june.cs.washington.edu (Dylan McNamee) writes:

>I found the size of the ROM by guessing and checking.  The system crashed
>when I was wrong.  

That's not a bad way to find it, actually.  You aren't guaranteed to get
the whole ROM by randomly guessing, and you aren't guaranteed to not get
any registers by running Wack or Metascope to poke around for the ROM. 
But it is a foregone conclusion that mapping the I/O into RAM will crash
or hang the system.

>Now for the wierd part;  I'm not getting _any_ performance improvement.

I didn't get much of a speedup on the 2090A version at first.  The 2091
code is supposedly tighter, and alot of it depends on where your
bottleneck is -- if you spend all the time waiting for the drive, the
code efficiency (what CardROM helps out with) matters less and less.
The most striking performance difference in my home machine was when
I started running the 2090A in conjunction with 3 and 4 bitplane hires
displays.

>dylan mcnamee


-- 
Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests"
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                    Too much of everything is just enough