VT101 8085 CPU Fault

Robert Jarratt robert.jarratt at ntlworld.com
Sun Jan 18 14:07:30 CST 2015

No, I checked that and it isn't. It is an active low signal and it is high.



> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of tony
> 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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