Re: [stella] Indirect indexed addressing

Subject: Re: [stella] Indirect indexed addressing
From: Darrell Spice <dspice@xxxxxxxxxxxxxx>
Date: Mon, 26 Apr 2004 19:11:00 -0500

On Apr 26, 2004, at 5:34 PM, Manuel Rotschkar wrote:

Hi there!

Is it true that indexed-indirect addressing as LDA ($nn),Y is limited
to zero-page addressing?  Seems that way, with DASM throwing an error
if $nn > $FF.

Sad but true, yes.

Of course, this isn't usually an issue for 2600 programming
- I only bumped into it when coding for Superchip RAM - but it seems
like a pretty severe limitation for the 6502 in other environments?

I just checked, more than 1/4 of the C64 zero page is reserved for pointers to various 16-Bit adresses.

Another thing to consider, the other 6502 environments don't have to share zero page with the stack. If I recall correctly, the stack on the C= systems was $0100-$01ff.

Darrell Spice, Jr.

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