Date   : Tue, 14 Jul 2009 18:28:56 +0100
From   : acorn@... (Andy Ford)
Subject: Using a B keyboard on a Master

Thank you.

I sat looking at this a few minutes ago and decided to cut IC16 out, 
figuring this may help and if not I would simply fit a socket and obtain 
another one at a later time.

I am pleased to report the B keyboard functions now :) , I'd speculate I 
needed to cut another pin from it too (as well as pin 38) to achieve my 
original aim, but now its no longer present it's fine. The cassette 
motor led does not work but that is not a problem really anyway (this 
Master PCB does not have a cassette motor relay, the previous owner had 
removed it by the looks of it, it did have one once as I can see 
evidence of it) , plus I may just turn that led into a "power on" led as 
per the usual Master spec.

I will obtain a socket , clean the pcb up and fit that anyway at some 
point, mainly for neatness and the ease of returning it to normality if 
required, although it seems happy in its new home. Just have to stop and 
think carefully about not overloading the B power supply I am using really.


Andy :)


Johan Heuseveldt wrote:
> That's indeed the experience I had.
> I have only one Master with a socketed keyboard encoder. When
> this was removed, the model B keyboard was fully functional!
>
>   
>> Otherwise there seems to be no links or jumpers to select it... if
>> it's not, snip pin 38, nKBEN (in a way that means you can solder it
>> back together again) and see if that helps...
>>     
>
> I assume that the software isn't aware of two keyboards possible,
> and with two conected there is a hardware clash somehow.
>
> Please note that the keyboard encoder -in discrete logic - is
> built onto the PCB of the model B keyboard (so only 17 wires).
> The Master keyboard is just a dumb matrix, and its keyboard
> encoder is a single custom chip on the Master mobo, therefor
> losts more wires!
>
> I think both encoders get adressed simultanously, and the
> system can't cope with that? Both generating an interrupt?
>
>
>
> Greetings,
> Johan
>
>