Fwd: Re:6526-8521(8520)Differences 6510 and 8500 differences (fwd)

From: Ray Bryan (raycomp_at_visi.com)
Date: 2000-07-31 18:14:05

Is anyone testing the differences between the CIAs 6526 (orA)(C64) 
and 8521 (C128 and some C64c's) or 8520 Amiga 500/1000/2000/3000 -- 
that address, $DExx, is in the CIA.  What about differences between 
8501(7501) and 8502 and 8500?

>---------- Forwarded message ----------
>Date: Sun, 30 Jul 2000 11:43:01 +0200
>From: Nicolas Welte <welte@chemie.uni-konstanz.de>
>Reply-To: cbm-hackers@dot.tcm.hut.fi
>To: cbm-hackers@dot.tcm.hut.fi
>Subject: Re: 6510 and 8500 differences
>Richard Atkinson wrote:
>>  I'm going to leave the C64C and C128D on all night. Depending on how low
>>  the 8500 result is tomorrow, it may be possible to arbitrarily set a
>>  'reasonable' cut-off point between 6510 and 8500, but it would only be
>>  accurate after the machines have been on for some time and there would be
>>  the possibility of erroneously detecting C64s as C64Cs for recently turned
>>  on machines.
>Thanks for all the measurements, Richard! I'm also quite amazed that we
>have a temperature sensor in our CPUs, this is something that just
>became popular with the Pentium III and it's integrated temperature
>diode. We had it for 18 years! (But didn't know about it)
>A bit more accurate measurements (cycle exact with the CIA timers,
>connected to a 32bit timer) would be nice, but if there already is an
>overlap between 8500 and 6510 values it doesn't really make sense. I did
>some measurements of that kind already on the two SID types, but soon I
>found one 8580 that wasn't much different from most of the 6581, so I
>kind of stopped looking at more machines. I might have another go and
>study the temperature dependenance, if it also affects the SID effect.
>But then I would also include CPU measurements so I could get both
>values at once.
>Are there any more registers with unconnected bits that could be looked
>at in a similar manner? I don't know of any such bits in the CIAs or in
>the VIC-II.
>>  How well defined is the $DExx functionality difference between C64s and
>>  C64Cs? I feel sure we're on the right track, but will have to put in some
>>  considerable refinements to the process to achieve a high level of
>>  accuracy from the moment a machine is powered up.
>In any case a machine type detection program must examine this
>functionality, but I already said that a few (probably slightly damaged)
>"C64Cs" fail this test. It also isn't a 100% sign for a 8500.
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|Raymond C. Bryan  651-642-9890 vox      | The battle is sometimes |
|Raymond Computer  651-642-9891 fax      | to the small for             |
|795 Raymond Ave   -email:  raycomp         | the bigger they are        |
|St Paul MN  55114    @visi.com                  | the harder they fall.      |
|USA              Amiga - Commodore               |     -- James Thurber -- |
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