John,
I received all of Dr. Wilcox's engineering notes, book corrections, and
hand-wrapped 68K board from him a couple of years ago. My intention had
been to scan the notes and the book errata and place them on a web site as
he indicated that he had no problem with that as long as credit was
Hi John
The problem is the data does not stay valid long enough after pWR* goes high.
It is discussed on pages 335-337 of book. Also the 8255 requires the data be
valid at least 30 nsecs after write signal goes high. The same type of issues
occur on propeller and IDE select on the IDE
