Re: Ultimax questions

From: Rob Clarke <>
Date: Sun, 20 Oct 2013 23:35:38 +0200
Message-ID: <>
On 20/10/2013 21:56, Michał Pleban wrote:
> Then I'm afraid you either need to use two EPROMs, or two latches. Two
> EPROMs, one RAM and one latch will unfortunately not fit in a cartridge.
> Two latches, RAM and EPROM - maybe, I haven't tried but it's still hard.
> Unfortunately if you do not switch to a larger EPROM, you may be stuck
> with 8 kB images.
I think it'll be larger eproms, I found some 040's for around £1 each.

>> How about AND'ing pin 10, which is /IO2 on the 64 and /CIA on the MAX,
>> with A7? On the assumption that none of the MAX ROM's don't write to any
>> of the CIA's mirrored registers during their normal operation we could
>> use a write to $DC80 and $DF80 on the MAX and 64 respectively?
> /IO2 is not /CIA on the MAX, it's the CIA's shift register output.
Are you sure about that? According to the reverse engineered schematic 
on zimmers

the shift register is on pin 6 which is the dot clock on the 64. Pin 10 
is /IO2 on the 64 and the CIA select signal from the MAX's PLA.


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Received on 2013-10-20 22:00:13

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