coco2 key remap poke?

[ceratophyllum]

Is there a way I can remap a key with a poke in immediate mode?

 

I have extended color basic on a coco2 and my G key will not work. Would be nice to make some other key do ASC(71).

[Rolo]

I don't see a simple poke. The key-matrix is hardwired and the ASCII conversion is calculated, depending which PIA-lines have been connected by the keystroke ($A1FB). I don't see no universal keypress-to-ascii table. There is just a table for some special keys, like the arrows, BREAK, ENTER, @ in rom at $A26E.

Correct me, if I'm wrong.

 

You probably have to clean the switch's contact, if that can be opened somehow. Can't you get some contact spray into the switch? I don't have no CoCo, so forgive my probably silly suggestions.

[ceratophyllum]

The keys press down on a sandwich of clear plastic sheets with some kind of conductive paint traces.

 

-------top circuit sheet

-------insulator sheet with holes under keys

-------bottom circuit sheet

 

The sheets are bound together in the corners so that they stay aligned.

 

I gave the area around G a good spray of contact cleaner but the key is still not working. There is nothing special to the naked eye about that particular key's movement or the point it presses down on. Maybe I'll take out the 18 (no kidding!) tiny screws again and have a look with the ohmmeter.

 

Not sure how I would fix a flakey trace...Circuit Pen, I guess.

 

 

[Rolo]

You could already now make some resistance measurements at the end of the "ribbon cable" and compare the values of different keypresses, to see, if "G" is totally out of range or just a bit out of tolerance.

[ceratophyllum]

I just got around to checking and I got 750 ohms across 1 and 16 for G pressed down.

 

I tried F and O and got around 300 ohms.

 

I think the problem is on the trace16 of the flat, cable sticking out because the resistance increases a great deal in just a few cm closer to the end. If I move the probe up the trace toward the keyboard (keeping the other end fixed, of course), the resistance is more like 360 ohms.

I have seen this before with my other coco2 keyboard: oxidation or something eats these traces up. That one had it so bad you could see the break. I just tried painting over the high resistance section of trace with a CAIG Circuit Writer pen and went from I,O, J,K, N, M not working to all but O working.

 

The ink takes a very long time to fully dry and the resistance of the wet ink is high. Maybe I'll wait another 24 hours before I check again.