Re: Disabling memory refresh in UltiMax mode

From: Segher Boessenkool <>
Date: Sun, 11 Dec 2011 21:40:02 +0100
Message-Id: <>

>>> Interesting! I suspect that is an 8520 actually... Can you test  
>>> that?
>> It's soldered to a C64 mainboard and behaves like a 6526A as far as
>> the software goes. The 8520 doesn't have the RTC but a 24Bit timer
>> instead as far as I know, so I think you'd notice if you tried to
>> use a 8520 instead of a 6526.
> Not if you do not use any program that uses the TOD. And there are not
> many that do. The KERNAL does not use the TOD at all.

Yep, exactly.

>>> Supposedly they also did an 852x that has only the low four ports  
>>> (or
>>> the rest is not functional, anyway), i.e. the two parallel ports  
>>> only;
>>> it was called something like 5210 (I forgot the exact name, and  
>>> cannot
>>> find it anymore).
>> 5710 if I remember right.
> The 5710 from the 128DCR (and 1571CR)?

That's the one.  Pretty obvious how they came up with that chip name,
heh :-)

> That's more than a stripped-down
> 6526, as it also contains "an equivalent" (well, or so...) of the
> WD1770/1772 for MFM access.

Ah, that makes a lot more sense, thanks for the info.


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Received on 2011-12-11 21:00:38

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