[Coco] GIME questions

[jdaggett at gate.net]

Robert

That is why I asked if he was stepping through his code or DECB or 
what? I am somewhat familiar with what DECB does. I wrote a code 
fragment that not necessarily the exact fragment within the COCO 
but as a tool to show  how it "COULD" be done. 

I had questions as to what David's software was doning and he  has 
answered some. 

james


On 16 Aug 2004 at 9:42, Robert Gault wrote:

Date sent:      	Mon, 16 Aug 2004 09:42:00 -0400
From:           	Robert Gault <robert.gault at worldnet.att.net>
To:             	CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
Subject:        	Re: [Coco] GIME questions
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> Robert Gault wrote:
> > David Gacke wrote:
> > 
> >> Hi Guys,
> >>
> >> I've got a GIME problem and I'm not sure what's going wrong. For
> >> some reason, "I think", it's not mapping RAM correctly.
> >>
> >> I'm stepping thru the startup ROM code on my CoCo 3, which matches
> >> the version I'm looking at in MESS. Just a plain old CoCo3 ROM.
> >>
> >> Anyway, there's a write to $FF90 with a value of 0x0A, then there's
> >> some startup code to set palette registers to all green, then
> >> there's some code to start copying code from $C03F to $4000.
> >>
> >> This is where I get into trouble. Immediately after writing the
> >> first word, with the STD, Y++ instruction, I read back the
> >> contents. The address I'm reading from is $4000 and I'm seeing the
> >> same data that is at $C000.
> > 
> > 
> 
> OK just so everyone is on the same page, the code in question is from
> the 32K ROM in a Coco3 and is as follows:
> 
>   lda #Coco+MMUEN+MC3+MC2+MC1
>   sta $$FF90
>   leax begmove,pcr
>   ldy #$4000
> LC02F ldd ,x++
>   ldu ,x++
>   std ,y++
>   stu ,y++
>   cmpx #endmove
>   bcs LC02F
>   jmp $4000
> 
> David asked why when stepping through this code, the contents of $4000
> = that of $C000. He may have meant begmove. Regardless, the content at
> $4000 should be RAM and will look like whatever regY contained after
> the std ,y++.
> 
> David, would you clarify what your problem is?
> 
> 
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