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. ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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