Re: Ultimax questions

From: Rob Clarke <crock_at_clarke-family.org.uk>
Date: Sun, 20 Oct 2013 23:35:38 +0200
Message-ID: <52644CAA.7010706@clarke-family.org.uk>
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

http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/maxschematic.jpg

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.

Rob

       Message was sent through the cbm-hackers mailing list
Received on 2013-10-20 22:00:13

Archive generated by hypermail 2.2.0.