Re: [cc65] C64DTV: different stack and zero page position + cc65

From: Ullrich von Bassewitz <>
Date: 2010-11-29 21:46:09

On Mon, Nov 29, 2010 at 03:48:39PM +0100, Gábor Lénárt wrote:
> I'm thinking to try some coding on my little C64-DTV3. However a question
> has come into my mind: is there any requirement (of cc65) that zero page is
> always at location $0000 and stack at $0100?

I'm not aware of any such requirement. I cannot rule out that there are a very
few library modules that use something like

        lda     $104,x

but if so, I would assume that they are platform specific anyway.

There may also be accesses to the zero page using non zero page addressing
modes, but I cannot currently imagine when this could happen. At least there
are no such tricks in the compiler.

So while I cannot completely rule out the possibility that there are such
constructs, I do assume that chances are very good that your code will run
without problems.

> It's a question because on DTV
> you can relocate them (but as far as I know it's true for C128 too?), so for
> example STA $00 and STA $0000 won't mean the same memory location anymore.

The C128 has a MMU that does actual memory remapping. So on this machine, when
the zero page is remapped, accessing it using absolute addressing will still



Ullrich von Bassewitz                        
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Received on Mon Nov 29 21:46:18 2010

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