Re: Ultimax mode VIC II access to external RAM?

Den Thu, 03 May 2018 11:25:26 +0200 skrev Michał Pleban
<lists@michau.name>:
> Hello!
> 
> Jim Brain wrote:
> 
> >> Or do you mean attaching additional RAM in the unused address
> >> space, for example $1000-$2FFF (for which you must do your own
> >> address decoding)? Then I don't know exactly whot would happen,
> >> but my gut tells me that in the real Ultimax VIC would see this
> >> RAM, but in the C64 it might or might not (my bet is on "not").
> > This is the case I am wondering about.
> 
> OK. I don't have a C64 laying around, but the easiest thing to do
> would be to plug MAX BASIC Ultimax cartridge, program the VIC from
> the BASIC to access this memory area, and use the logic analyzer to
> see what;'s on the bus. In the real Ultimax I am 99% sure the VIC
> will see it, but on the C64 it's not so certain.

I've read somewhere that one of the decoded I/O select lines on a C64
were once the decode for more memory on a MAX/UltiMAX. Maybe that is
used instead of a real decoder in the MAX/UltiMAX basic cartridge?

-- 
(\_/) Copy the bunny to your mails to help
(O.o) him achieve world domination.
(> <) Come join the dark side.
/_|_\ We have cookies.