On 2015-03-04 20:20, Gerrit Heitsch wrote: >>> VIC is not that much of a problem. Despite the 6569 running quite >>> hot it doesn't die very often and there are still lots of them >>> available. TED is a different story since not as many were made >>> and the earlier ones (R1 and R2 with '84 datecode) seemed to die >>> easily. >>> >>> I'd be more worried about the availability of the 6526 / 8521. >> >> 8520? > > No, the 8520 is the CIA for the Amiga. Right - and quite similar to the 6526 in many respects. AFAIR it was something like a 6526 stripped from the timer(s) or so. > If you own a C64 made at the end of 1986, check the CIAs, with some > luck you will find a 8521R0 instead of a 6526 I see - now when you say it, I vaguely recall seeing something else in place of the 6526 once or twice ;-) This must have been a case like the one you mention. Anyway this was a really rare experience. So rare that I didn't even memorise the markings although I now recall the surprise that it wasn't a 6526 while it worked. > (I own a 250466 board with a 8521R0 on U2 and a 1571 with one ). > Later Commodore went back to the '6526' label, That explains the scarcity. > but the die inside is still a 8521. Which probably is an "augmented" 8520 that gives back what was missing in order to be fully 6526 compatible. > The CIAs are not as easy to implement as one would expect. Digitally > yes, but then there's the analog side (the way the output drivers > behave) that will be hard to duplicate with todays technology. ? Interesting. I always thought of 6526 in the digital domain only. What was so peculiar about the 6526's output drivers. I haven't experienced any problems interfacing it to other chips… maybe something on the serial lines? > Some programs use that with the CIA for the keyboard. ? -- SD! Message was sent through the cbm-hackers mailing listReceived on 2015-03-04 20:01:21
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