VT101 8085 CPU Fault
robert.jarratt at ntlworld.com
Sun Jan 18 18:05:10 CST 2015
Does anyone know the whereabouts of an online copy of the field maintenance print set for the VT101? It's part number is MP-01066.
> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Johnny
> Sent: 18 January 2015 22:53
> To: cctalk at classiccmp.org
> Subject: Re: VT101 8085 CPU Fault
> On 2015-01-18 23:04, Diane Bruce wrote:
> > 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.
> If the RD pin never gets active, the contents of the ROM will not even be
> presented to the CPU, so while it's possible the ROM is borked, that is not the
> problem we're trying to fix right now.
> Johnny Billquist || "I'm on a bus
> || on a psychedelic trip
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