[Coco] Re: 64K Mode

[jdaggett at gate.net]

John

According to the diagram that I have in the 1983 databook it shows 
that the ram in memeory map type 0 as two pages of ram at $0000 
to $7FFF. Unless this is inerror then that is what I am basing mt 
posts on. 

Rom seems to remain constant in memory Map type 0 In memory 
map type 1 the ROMs are wswitched out and ram is mapped from 
$0000 to $FDFF. 

james

On 13 Jan 2004 at 20:21, John E. Malmberg wrote:

To:             	coco at maltedmedia.com
From:           	"John E. Malmberg" <wb8tyw at qsl.net>
Date sent:      	Tue, 13 Jan 2004 20:21:01 -0500
Subject:        	[Coco] Re: 64K Mode
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> Brad Grier wrote:
> > 
> > I'm confused by this. Are you saying the P1 register at 0xffd4 and
> > 0xffd5 allows two banks of lower 32k ram? None of the 64k programs I
> > have write to this register. Are there any programs that do this?
> 
> The Color Computer SAM chip can access 64K of dynamic RAM, and almost
> 32K of ROM or static RAM.
> 
> You can MAP either 32K in the bottom section, and swap the upper 32 K
> as 
>   ROM / RAM.
> 
> There has been one example of a program that apparently is not
> currently available that takes advantage of this.
> 
> And there could easily be a ROM pack that would swap out the lower 32K
> as needed.
> 
> > According to my color computer reference manual, "Register P1
> > controls a feature which is not used in the Color Computer.
> > Therefore it should be cleared at all times." Is that pre-64k?
> 
> The Motorola Manual explains all. :-)
> 
> -John
> wb8tyw at qsl.net
> Personal Opinion Only
> 
> 
> 
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