18 Jan
2015
18 Jan
'15
11:15 a.m.
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?
-tony