Den Mon, 18 Jun 2018 19:01:27 +0200 skrev Michał Pleban <lists@michau.name>: > Hello! > > Ruud@Baltissen.org wrote: > > > But if an output and input are connected to each other, is that > > still the case? I can imagine that a cell used for an emulated > > output can be used for the emulated input as well. > > This is generally true, if the pin is unidirectional; for > bidirectional pins, you still need both macrocells. However, in the > situation on the 8088 card (when the whole data port has always the > same direction) you can save on the cells for DDR. Then I think we are back at the possibility to roll your own port using 74xx logic. But is this true regarding PB or only PA of the 6526 and 6523? PB seems to be used for various handshake signals and a few of them have external pull-up resistors indicating that in some states both might be set as inputs. P.S. As I understand the schematics of the 8088 board, PB7 isn't used on the 6523, and PC0-4 and PC6-7 is also unused. This gives me the impression that a 6522 could be used, with the apropriate software changes. -- (\_/) Copy the bunny to your mails to help (O.o) him achieve world domination. (> <) Come join the dark side. /_|_\ We have cookies.Received on 2018-06-18 21:02:37
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