Re: Disabling memory refresh in UltiMax mode

From: Gerrit Heitsch <>
Date: Mon, 12 Dec 2011 17:02:20 +0100
Message-ID: <>
On 12/11/2011 09:40 PM, Segher Boessenkool wrote:
> [206A]
>>>> 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.

Well, one should be able to test that by plugging a real 8520 into a C64 
board and then trying some software. If there is a program that 
complains/crashes, then we know for sure that the 6526A marked '206A' is 
not a 8520. :)

>>>> 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 :-)

Well... 5xxx = CMOS, x7xx = gate arrays. See also 5717, 5719 and 5721.


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Received on 2011-12-12 17:00:04

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