Re: Synertek 6502 compatibility

From: didier derny <>
Date: Wed, 11 Apr 2012 09:25:45 +0200
Message-ID: <>

the synertek components are known to be bugged.
that's why we only used mos technology or rockwell.

the 6522 and the 6551 where badly bugged
but I never heard of this specific bug....

I dont know if these bugs were ever fixed.


Le 11/04/2012 00:42, Rob Clarke a écrit :
> 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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Received on 2012-04-11 08:00:10

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