Synertek 6502 compatibility

From: Rob Clarke <*crock_at_clarke-family.org.uk*> Date: Wed, 11 Apr 2012 00:42:08 +0200 Message-ID: <4F84B740.4090206@clarke-family.org.uk> · crock_at_clarke-family.org.uk

Hello gentlemen,

Does anyone know if the Synertek 6502 is 100% compatible with its MOS 
cousin? I have one which I tried in an otherwise working PET and I get 
"31653.4784 BYTES FREE" instead of 31743, which is 89.5216 bytes short :-/

I know some of the later CMOS incarnations did not have the same 
behaviour with undefined op-codes but a) this a 1984 chip and b) I can't 
believe the PET kernal would use them anyway.

It is also possible that this chip is just duff of course.

Rob

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