VT101 8085 CPU Fault

tony duell ard at p850ug1.demon.co.uk
Sun Jan 18 13:15:46 CST 2015

> The terminal controller board on my VT101 is not working, if it displays
> anything it is random characters. I have used my scope to check the 8085
> CPU. It has power, it is outputting a valid clock, but there is no activity
> on the RD,WR and ALE pins. I am guessing the 8085 is bad, but before I go
> replacing it I wanted to check if anyone knew of anything else that might
> cause the 8085 to misbehave (ie am I seeing symptoms or a cause?).

What is the state of the reset input to the 8085? In other words, is the CPU
being held reset all the time?


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