VT101 8085 CPU Fault

[Robert Jarratt]

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Diane
Bruce
> Sent: 18 January 2015 22:05
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: VT101 8085 CPU Fault
> 
> On Sun, Jan 18, 2015 at 09:47:35PM -0000, Robert Jarratt wrote:
> >
> ...
> > > you more. Nice sharp edges to signals when they shift. Times that
> > > look reasonable... Steady levels, and correct levels.
> >
> > It will never be steady with a scope because the address lines won't be
a
> regular waveform. That said they looked very different on the faulty board
to
> how they looked on the good board.
> >
> 
> A remote possibility is the boot ROM is b0rked and it's simply running
around
> like a chicken without a head.
> That is something a good logic analyser could tell you.
> 


I would have thought that unlikely as I would expect to at least see some
activity on the RD and WR pins, but I don't. I mean even if the ROM is bad
it would execute *something*.

Regards

Rob