Re: 264 Series and their chips

From: Gerrit Heitsch <>
Date: Sat, 13 Aug 2011 19:11:28 +0200
Message-ID: <>
On 08/13/2011 06:23 PM, wrote:
> Hallo Gerrit,
> Have you ever thought about replacing the 8501 with a 8502 from a
> C128? So far I found four differences:
> - the 8501 has this MUX input (or output? I have no idea what it
> does) which the C128 lacks
> - the 8502 has an "extra" NMI input compared to the 8501
> - the 8501 lacks the P5 I/O pin, the 8502 P7
> - pinout doesn't match
> If the MUX gate doesn't spoil things, what about using the 8502?
> Regarding P5/P7: you either don't use the cassette recorder anymore
> or adjust the bits of the Kernal.

Haven't tried that yet, but the 8502 isn't an easy to find IC and I 
don't want to take spare parts away from the C128 users.

 From what I read, you'd have to rebuild the GATE_IN logic by hand since 
leaving that pin unused on a 8501 screws up memory now and then.


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Received on 2011-08-13 18:00:07

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