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. GerritReceived on 2018-06-10 23:00:04
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