On 7/5/2014 1:20 PM, Gerrit Heitsch wrote: > On 07/05/2014 08:13 PM, silverdr@wfmh.org.pl wrote: >> On 2014-07-05 at 20:02:07, silverdr@wfmh.org.pl >> (silverdr@wfmh.org.pl) wrote: >> >>> again the datasheet if they really meant "$(0)FFF" and not just >>> shortened the full "$FFFF" >>> ;-) But it also clearly states that only 2KiB of ROM is available. >>> Impressive. >> >> I was also interested how they did it internally. Like if they >> changed the 6502 core (doubtful) or for example wired the two upper >> address nybbles together or something like that... > > That should be easy for Jim to find out. Dump page 0F und page FF and > see what you get... Ran the test. page ff and page f show the same data. > > Maybe they just made the upper 4 address bits "don't care" by not > including them into any selection logic? That way their state doesn't > matter and you don't need to change the CPU core at all. Since that's the easiest to do and requires the least amount of IC space, I'm voting for that. Message was sent through the cbm-hackers mailing listReceived on 2014-07-05 20:01:08
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