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Old 28 May 2020, 21:13   #11
jasonsbeer
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Join Date: May 2020
Location: Iowa, USA
Posts: 150
Quote:
Originally Posted by demolition View Post
Sounds to me like there is some action going on on that pin (which there should be until it has finished running the code in ROM).

_ROMEN will only be pulled low while the CPU is reading from it so it would be high most of the time. If you're just using a voltage meter, then the voltage you see would be some kind of average depending on how the meter handles high frequency signals. Imagine _ROMEN is a pulse train which is low 20% of the time, then the average voltage would be ~4V.
That makes sense. I just need to be patient and wait for my logic probe.

BTW - I did get the diagrom today. I put it in and still black screen. Null modem is also on the way.
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