[stella] Re: ZP,Y -> ABS,Y

Subject: [stella] Re: ZP,Y -> ABS,Y
From: "Eric Ball" <eball@xxxxxxxxxx>
Date: Thu, 24 Oct 2002 16:02:06 -0400
Christopher Tumber wrote:
This was one my biggest "gotchas" switching over from a CPU like 6809 where
x and y are much more interchangeable. At least when I'd drop in a memonic
like CMPX or ADDA I'd get an error but DASM is more than happy to assemble
illegal zeropage,y as absolute,y commands.

That's not a bug, it's a feature!  DASM assumes that since the 6502 doesn't
have a ZP,Y, that you must have meant ABS,Y.

I have to admit that the 6809 has a nice ISA.  I cut my teeth programming
in assembly on the CoCo and it was quite a shock when I tried to get down &
dirty on an Apple ][; no 16 bit index registers!  Only a single 8 bit
accumulator!  No multiply instruction!  Aaagh!  And I nevery understood the
Apple's hi-res graphics memory map.

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