[Coco] GIME questions

[jdaggett at gate.net]

Willard

By writing a "0" to the MMU bit of $FF90 you tu rn the MMU off and 
from my understanding the top 64 K of physical memory become 
logical memeory. Thus a write of $0A will put 32 K ROm from 
$8000 to $FFFF of logical memory and that will map to $78000 to 
$7FFFF of physical memory in a 512K system. 

james




On 16 Aug 2004 at 3:06, Willard Goosey wrote:

Date sent:      	Mon, 16 Aug 2004 03:06:05 -0600
From:           	Willard Goosey <goosey at virgo.sdc.org>
To:             	coco at maltedmedia.com
Subject:        	Re: [Coco] GIME questions
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> 
> >From: "David Gacke" <dgacke at ektarion.com>
> >Date: Sun, 15 Aug 2004 21:48:33 -0500
> 
> >For some reason, it didn't get $4000 mapped correctly, it is still
> >pointing to ROM. Also, are there any special conditions I should be
> >aware of when writing these GIME registers, like wait states, etc.
> 
> I'm not an expert on the GIME, but IIRC ROM mappings override the
> regular MMU.  There are other bits you need to twiddle to tell the
> GIME not to put ROM there.
> 
> Willard
> -- 
> Willard Goosey  goosey at sdc.org
> Socorro, New Mexico, USA
> "I've never been to Contempt!  Isn't that somewhere in New Mexico?"
>    --- Yacko
> 
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