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The 6809 had a really nice instruction set, but it didn't really perform any better than the 6502. The 65816 is a much better upgrade IMO, and the SuperCPU ran it at 20MHz over 20 years ago.

65xx at 32-bit (or 16-bit for that matter) would work so much better if they just widened the data bus. You'd lose drop-in compatibility, but the alternative - which WDC seems to have chosen - is to let 65xx die chained to the archaic bus interface of the 6502. Imagine if x64 was still using the sa...

For context: I've learned a good amount about writing a game in assembly, so I'm wondering if I should consider writing any parts of a game in a higher level language. Beyond what others have said, you can dramatically raise the level of assembly language by using macros, making the source code muc...

Imagine haveing a 7mhz 6502 For many years, all of them being made have been guaranteed for at least 14MHz, and the off-the-shelf ones usually top out around 25MHz, if the supporting parts can work at that speed. See WDC's data sheet at http://6502.org/documents/datasheets/wdc/wdc_w65c02s_oct_8_201...

IF_GE ; Is the value above 127? [Shouldn't that say "above 61"?] I think my reasoning was that at that place in the code we don't know which direction we've offset in. It could probably be reworked a bit, since I'm checking for direction twice, but I've left it that way for now since it w...

I sort of follow what I'm used to from other languages just because it makes things easier for me to read and wrap my head around. I'm not super consistent with it but for me that's not really the point. I just want to be able to read and understand what I'm doing with the code, so with that I usua...

I agree with many of the points above (although not all). I indent to make conditionals and loops obvious, and also things like what's between a PHA and PLA for example. I always indent at least three spaces. One or two spaces are just enough to make it look like you just got really sloppy at vertic...

We had basically the same conversation on 6502.org, at http://forum.6502.org/viewtopic.php?f=2&t=5317 . Various code suggestions were made there.

Not really sure the 65816 has anything to offer over a 6502.. True, but for this specific purpose, both the 65816 and an authentic 6502 have something to offer over the slightly cut-down 6502 in the 2A03: the ALU reacts to sed . I didn't comment on this earlier because I figured it was regarding th...

Be sure to see http://6502.org/source/integers/hex2dec.htm and http://6502.org/source/integers/hex2dec-more.htm .

I've never had the problem mentioned in the head post, knock on wood. In fact, for me, macros have prevented loads of bugs and saved me a lot of time. I sense that in many cases others make very poor use of macros though. I'd have to see a lot of examples in order to identify a pattern of what's hap...

May I broaden the scope to scaled-integer ? Because fixed-point is just a limited subset of scaled-integer arithmetic. The first half of the front page of the section of my website section on large look-up tables is an article about scaled-integer, showing how to do things with it that most people d...

2. Slow and more comfortable - Use hardware stack, which is so-so for A register, but quite slow for anything else as it would require lda mem, pha, pla, sta mem for every variable You don't need to constantly be pulling stuff off the stack and putting it back on. Nor are you limited to just the by...

See the 6502 interrupts article at http://wilsonminesco.com/6502interrupts/ , especially starting with 1.3 at the subtitle "GETTING TO THE NUTS AND BOLTS." Oh, and uh... Enjoy my outdated cartoons.

But why would you ever need to use indexed indirect addressing with the X register? What practical purpose does this serve? There has to be some situation where this feature would prove useful, otherwise I'd assume it wouldn't be featured in the processor design. Have you ever used indexed indirect...