VT1x1 keyboard (was Re: VT101 screen adjustment)

Adrian Graham witchy at binarydinosaurs.co.uk
Tue May 10 14:26:21 CDT 2016

On 10/05/2016 16:14, "tony duell" <ard at p850ug1.demon.co.uk> wrote:

> The keyboard itself is the same on the VT100, VT101, VT102, etc. The interface
> circuit on the main logic board is much the same too, so the info in the
> technical manual is of relevance.

I'm reading that in moments of quietness since the VT101 is showing random
key decoding no matter which keyboard is plugged in. It only does it during
keypresses so it doesn't seem to be a random bit setting itself.

If I press and hold for example 's' I'll get several 's' on screen then
something else will happen, then more 's'. +5V on the board is at +4.96V and
the VT POSTs correctly so it's not an obvious RAM glitch, and it doesn't
seem to be a warmup problem either.
> If you can stick one of my hand-drawn diagrams, I have reverse-enegineered
> the VT101 logic board and PSU board. Keyboard and video you can get from
> the VT100 printset, and I couldn't find a mains input bracket to trace out
> (maybe
> sometime) but that is pretty simple anyway. If you want the VT101 board
> diagrams just ask me nicely.

I always ask nicely don't I? :) Drawings would be excellent please, and in
return I can send pics of any internals you need including a mains input
bracket. I had the VT131 one in bits on Sunday to fix the power switch which
had disintegrated in the same way my VT102 did.


Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer

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