VT101 8085 CPU Fault

Bob Rosenbloom bobalan at sbcglobal.net
Sun Jan 18 14:11:07 CST 2015

On 1/18/2015 12:07 PM, Robert Jarratt wrote:
> No, I checked that and it isn't. It is an active low signal and it is high.
> Regards
> Rob

What about the READY pin? Stuck low?


>> -----Original Message-----
>> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of tony
> duell
>> Sent: 18 January 2015 19:16
>> To: General Discussion: On-Topic and Off-Topic Posts
>> Subject: RE: VT101 8085 CPU Fault
>>> 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
>> being held reset all the time?
>> -tony
>> =

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