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Old 17th Sep 2020, 1:34 pm   #47
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 1,155
Default Re: I found it !. A very sorry looking MK14

Disclaimer: I havent actually probed an MK14 with an oscilloscope recently
According to the data sheet the address lines are only driven while NBREQ is low, which is from just before NADS goes low to just after NRDS/NWDS goes from low-to-high; that means the address bus can be floating from (just after) the positive edge of NRDS/NWDS to (just before) the falling edge of the NADS.

Anyhow, its worth investigating and reverse-engineering your veroboard just to know what its doing!
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