Re: 6502 vs. 65c02

I've been quiet for a while, so it's time to overanalyze a bit....

65C02 is a CMOS 6502. Some on here say it's incompatible. Well, sort of....

A 65C02 will USUALLY work in place of a 6502. There are some differences, but
they shouldn't pose a problem. Actually, 65C02's from different manufacturers
are necessarily compatible with each other! Each manufacturer took a slightly
different approach on which new instructions to add, whether to allow wait
states during a write cycle (a 6502 doesn't), etc.

HOWEVER, normal code (by normal I mean code that doesn't use undocumented
"features") written for an NMOS 6502 doesn't use any of the added features, so
it really doesn't matter. If in doubt just plug it in and try it. You're not
going to hurt anything.

Now, about speeds. The 6502 series had the base part being good for 1 MHz, an
"A" suffix part is good for 2 MHz, and a "B" suffix is good for 3 MHz. This
gets a bit confusing if compared with the 6800 where the ratings were 1, 1.5,
and 2 MHz or the Z80's which were something like 2.5, 4, and 6 MHz. (Don't
feel too sorry for the "slow" 6502, a 1 MHz 6502 compares favorably with a 4
MHz Z80). CMOS 6502's may vary by manufacturer. Like I said before, just try
it. If you're real antsy about it just unplug the monitor first and run self
test or play the game blind. Either it will run fine or not---no harm done.

tom mcclintock wrote:

> I just picked up a couple of replacement 6502 processors for my Space
> Duel board, and I received the 65c02 processor instead. Now, I
> understand that the "c" signifies a clock onboard the chip (or was that
> something else...), but as I was looking for some information, I noticed
> that there are several different 6502 clock speeds.
>
> So, does it matter which version of the 6502 CPU I use on my Space Duel
> board?
>
> tm
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