On 2015-03-04 20:47, Gerrit Heitsch wrote: >> Right - and quite similar to the 6526 in many respects. AFAIR it was >> something like a 6526 stripped from the timer(s) or so. > > The 8520 had a normal timer instead of the RTC the 6526 had. That's > about it, you can use a 8520 in a C64 if the software doesn't use the RTC. You mean the TOD? I'd have to re-check. I did it too many years ago to publicly admit but I still remember that I did it because it was a rare service case. The machine worked but some games didn't work as expected and the owner brought it for check'n repair. I found (to my surprise at the time) that there was an 8520 installed. The 8520 itself seemed to be OK so I went checking the differences and it explained. Replacing it with a 6526 cured the problems. > Probably to keep customers from complaining... Especially since the 8521 > is not quite the same, if I remember right the timer IRQ is one cycle > late compared to the 6526. Doesn't really matter most of the time, > unless you use it where the timing is REALLY tight. Hm... it's interesting that so many years after one thought he knew practically everything about the machine - there are still things to discover again and again :-)) > This little tool will detect the CIA (and other chips) you have in your > box, a 8521 will be listed at '6526A': > > http://csdb.dk/release/?id=89406 And what if it is a 6526A? Or are all 6526As basically 8521s? -- SD! Message was sent through the cbm-hackers mailing listReceived on 2015-03-04 20:05:45
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