Re: R6502AP

Date: Thu, 27 Nov 2014 01:18:05 +0100
Message-ID: <4111124.Lh7aqHvZdO@rakete>
On Thursday 27 November 2014, 01:08:43 wrote:
> On 2014-11-27 00:54, wrote:
> > On Thursday 27 November 2014, 00:46:29 wrote:
> >> Should I expect any troubles after replacing MOS6502s with R6502APs?
> >> Undocumented opcodes' incompatibilities? Other gotchas?
> > 
> > rockwell and synertek licensed the 6502 from MOS, so these should be
> > identical to theirs...
> That would mean that they licenced down to the mask level. Was this the
> case? Or just rights to make own design based on the MOS one. If that's
> the same design then it should be compatible even with all undocumented
> opcodes.

as far as i know they licensed the mask (not only for the 6502, but also for 
other chips)

> > anything else probably not :) no idea how close other clones
> > are...
> The R6502AP is AFAIR a 2MHz Rockwell version. I got those in place of
> 1MHz MOS6502s, which I wanted. Wondering now whether I should return
> them. If they are indeed fully compatible / the same as MOS then fine.
> Otherwise I can envision some unpredictable things with e.g. the illegal
> opcodes.

you could try running the available test programs on it :) (eg put it into a 
1541 and run the testsuite by ninja (csdb) which is a port of the lorenz 
suite, and checks pretty much all important things except a few odd corner 
cases of the so called "unstable" opcodes - which are not terribly important 
for real world programs anyway)


Dick size still matters, just that money, race and in some extreme cases 
personality has a greater impact than an inch or two.

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Received on 2014-11-27 01:00:39

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