Re: R6502AP

From: Gerrit Heitsch <>
Date: Sun, 30 Nov 2014 14:36:07 +0100
Message-ID: <>
On 11/30/2014 02:25 PM, wrote:
> On 2014-11-30 02:48, Segher Boessenkool wrote:
>>> I ran the tests. Tried earlier but they take much longer than I thought
>>> so I finished only tonight. And.. the MOS 6502AD passes all the tests
>>> from that suite. The R6502AP fails repeatedly on one called "pc64-aneb".
>>> Since the mnemonics are different from what I once learned I don't know
>>> what command this is. Probably something from the AND family. But the
>>> difference is there every time I run the tests (why - BTW - does it have
>>> to spin the motor all the time?)
>> That seems (from the name) to be testing ANE, a.k.a. XAA, op $8b.
>> It is the most unstable unsupported op, giving different results
>> _per run_ on some MOS/CSG devices as well.  It is heavily temperature,
>> process, batch, phase-of-the-moon, you-name-it dependent :-)
> Mayby I should retest it during full moon :-)
> But since we only passed new moon phase - currently all runs are
> consistent: all three MOS chips I have left pass, while all Rockwells
> fail right away. It may be of little practical meaning but it seems to
> show that there is some difference in both chip's implementations.

Doesn't have to the implementation. It could be enough that they were 
made in 2 different factories.

But remember, Commodore used the R6502AP in their disk drives without 
any problems. So unless you plan something VERY esoteric, a failure in a 
test of a known unstable illegal opcode means nothing if all other tests 


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Received on 2014-11-30 14:00:48

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