Re: Can an apple II take a C64 microprocessor?

["Spiro Trikaliotis" <spiro.trikaliotis@gmd.de>]

Hi Chris,

Chris Collet wrote in message ...
>Or any other 6502 clone? I'd sure like to get a few more commands than the
>stock 6502 in my II plus. 

I want to tell you something about the C64's 6510.

1. It has no extra commands, it's core is exactly the same as the 6502
   (even the undocumented opcodes are the same).

2. The 6510 has no phi0, so it needs an external clock generator
   as opposed to the 6502

3. The 6510 has a modified timing.
   The 6502 (and the VIA 6522, the 6530, the 6532, ...) have a hold
   time bigger than zero after the falling edge of Phi2. This is not
   true for the 6510 (and the CIA 6526, the VIC 6569, the SID 6581),
   because the VIC-II (6567/6569) is a second master using the C64's
   system bus. So, with the falling of Phi2, the 6510 releases all its
   data from the bus which can cause real problems when interfacing
   with 'standard' 65xx chips (and 68xx, too).

4. The 6510 cannot address the adresses 0 and 1 on the external bus,
   because these two addresses are used inside for the built-in I/O-port,
   and they are only 6 bits wide.
   I don't know the Apple II, so I don't know if that's a problem, but
   I would expect so.

So, I would not even give it a try to put a 6510 in an Apple II
(and it would not give you any advantage at all).

>pull x and y directly onto the stack. I'm going to try it out anyway since
>I have a busted c64 laying around.


If you don't need you busted C64, then why don't you give it to me! ;-)

Spiro.