Z8530. 'Nuff said.
Well, not quite 'nuff...it's an AMAZINGLY nice chip! I've done
quite a bit with it (both in my designs and in existing systems) and
have always been impressed with its capabilities.
It has one gotcha that I remember. As ever, they ran out of pins on the
package, and didn't have room for a reset pin. Instead you do a hardware
reset by asserting rd/ and wr/ at the same time.
This is only a problem if you're trying to produce rd/ and wr/ from a R/W
line and you don't realise a momentaruy overlap (and the 'glitch' from
one LS TTL gate is enough) will reset the Z8530, or worse still partially
reset it.
Please don't ask how I foudn that out...
-tony