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Old 22nd Sep 2017, 9:32 pm   #31
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 378
Default Re: Help with 6802 Microcontroller

It is normal for NMOS devices to have a slower rising edge than falling edge but that should show on the address lines as well. Are you looking at read or write cycles? In one case the 6802 is driving the data bus, in the case of read cycles it is the addressed device and the edges might look different for a CMOS static RAM or the NMOS PIO.

Have you checked all the chip selects and control lines for the PIO? Maybe another bad track or a bad PIO.

Roger
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