On Sun, Jun 10, 2018 at 10:17:17PM +0200, Gerrit Heitsch wrote: > On 06/10/2018 09:46 PM, Segher Boessenkool wrote: > >On Sun, Jun 10, 2018 at 06:42:02PM +0200, Gerrit Heitsch wrote: > >>On 06/10/2018 05:36 PM, Segher Boessenkool wrote: > >>>http://siliconpr0n.org/map/mos/6526/mz_mit20x/ > >>> > >>>The ports are the low half of the pins (PA on the left, PB on the right). > >>> > >>>(I have a .xcf if anyone is interested, marked quite a few signals, but > >>>I haven't done the port stuff very much. It's about 400MB). > >> > >>That looks quite different from the one I posted. Looks like MOS did > >>quite a bit of redesign between the NMOS 6526 and the HMOS 8521 (which > >>still got labeled 6526). Might explain the little differences in the way > >>they behave. > > > >No, this is an actual 6526r4. This is an 8521r1: > > > >http://oms.wmhost.com/misc/MOS_6526A_CIA.jpg > > > >(and this is an 8520r4, the CIA used in amigas; it has a different TOD > >clock, and as you can see it's different from 8521 in other ways, too. > >But clearly 8520 and 8521 are more related. The lineage is almost > >certainly 6526 -> 8520 -> 8521: > > > >http://siliconpr0n.org/map/mos/8520/mz_mit20x/ ). > > Yes, but the 8521 is a drop in replacement for the 6526 (I have a C64 > Board with a 8521R0 on U2) and later revisions of that chip have been > labeled as '6526' again, probably to avoid confusing the customers. You > can tell them apart by the datecode or by the '206A' or '216A' next to > the datecode. _Almost_ drop-in replacement, yes. But the die photos are really easy to tell apart (an 8521 does not say "6526" on the die, it says "8521"). SegherReceived on 2018-06-10 23:01:24
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