Re: R6502AP

From: Segher Boessenkool <>
Date: Sat, 29 Nov 2014 19:48:07 -0600
Message-ID: <>
On Sun, Nov 30, 2014 at 01:54:30AM +0100, 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 :-)

Searching for   6502 opcode "ane"   gives you the visual6502 wiki
page for this as first hit.

(The other unpredictable op is $ab, "LAX"; all the rest are completely
predictable, although a few depend on whatever is on the bus if you use
RDY (which your 1541 testing does not use AFAIK)).


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Received on 2014-11-30 02:00:03

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