Has anybody seen keyboards like this? It has a big PCB with old 74 series logic on the back and it came with a circuit diagram that has the output as serial. I was going to just use the switch board like Andrew but now I think the serial interface is a better option with a PIC that gives more flexibility for translating the keys. It was as cheap as chips for 50p at a surplus shop a long while ago so I bought two. The downside is it probably uses more power than the whole QL being old logic. Some of the keys look German and there are many odd labels on others all a bit weird. I don't know if it actually works yet but if not it could be a point to point wire job.
It is amazing what I find in my attic like a commodore 64 that I couldn't remember buying. Later I had a flash back to doing a point to point keyboard wiring job on and then remembered I had put a spectrum 48K motherboard inside it. I can't remember ever using it though.
I was going to use the keyboard as is but I can't get it to give any serial signal out. Pulses and scanning of the keys seems to be happening but the circuit is difficult to read let alone understand making it difficult to fix. Given the power consumption is high with all the old TTL devices and I wouldn't want to add the load to the QL supply I am thinking it would be better to just use the switches like Andrew. There seems to be a frame around the switches so I wonder if it holds the switches in place or if the PCB is holding them? If the PCB holds the switches then I would have to cut off the chip parts of the board, cut all the tracks and hand wire point to point. What is the best option?
While thinking about this QL keyboard I remember hand wiring a keyboard for a Spectrum. Could a Spectrum keyboard plug in to a QL or is the matrix totally different? I could go searching for the Spectrum key matrix but I can't be asked.
I thought I would tackle this keyboard and desolder the switches to get the PCB off then hand wire the matrix like Andrew did but that didn't go to plan. Switches they are not they are Hall effect which might explain the complex circuit. I lifted the bottom right side of the PCB to free the first switch and the whole lot lifted up with no possible way to get them back. At least I took the PCB off but the insides of the switches came out very easily which means a PCB is the best way to go so now I am looking at chopping the existing PCB, removing all the chips, cutting the tracks and hand wiring the rest to form the QL matrix. Not sure if the Hall effect switches give '1' or '0' which might need inversion and get complicated again. Nothing is simple.
Maskenlos wrote:Are you going to implement this Keyboard into the original QL housing or will this be an external Keyboard?
It would be nice to have it like this one https://www.ebay.co.uk/itm/234542717042 ... 0290.m3507
but my keyboard has some funny button positions and it means cutting my original case that I don't want to do so no is the short answer.
Maskenlos wrote:Instead of doing all the re-wiring did you consider to use this?
Thanks for reminding me about your nice project but there is too much brain work required for me because my brain is somewhere else. Hacking and wiring bits I have knocking around is like a busman's holiday and easy for me to pick up and drop at leisure.
At least I took the PCB off but the insides of the switches came out very easily which means a PCB is the best way to go so now I am looking at chopping the existing PCB, removing all the chips, cutting the tracks and hand wiring the rest to form the QL matrix. Not sure if the Hall effect switches give '1' or '0' which might need inversion and get complicated again. Nothing is simple. 
