Re: Difference between 6502 & 65C02

[johnlb@primenet.com (John Bowling)]

In article <96082.140914JCA31@maine.maine.edu>,  <JCA31@MAINE.MAINE.EDU> wrote:
>I'd like to know what it is that's different between these two cpu's,
>apart from one being a CMOS chip. I'm also curious as to why I my II+
>'sort-of' works with a 'C02 in it. I'd think that the machine would
>either run, or crash miserably, but instead, it just seems to have
>trouble keeping track of numbers ..?something to do with operating
>modes, maybe?
>
A 65C02 will work in place of a 6502 unless you are running code that has 
used 'undocumented' operations in the 6502.  Some of those undocumented 
operations were used as part of copy protection as well as trick code.
If the code is ALL standard 6502 code, you should not have a problem.

Several new op codes were put into the 65C02, which improve it's operation.

There is another possible problem:  Not all 65C02s are the same.  
Rockwell created their own 65C02 with a series of bit operators which are 
not part of any other manufacture's 65C02.
--
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John Bowling             |Apple II GS can whip the pants off its little
johnlb@primenet.com      |brother (Mac) any time!
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