So I have now tested the Microbee with software and I can report I have successfully loaded several old tape games. It did highlight two issues: Two of the keys were not registering at all.
I carefully desoldered them but couldn’t work out how to get into them at first. They seemed quite different to the key replacement guide I’d found, but then I found a second one that was much more useful. this one covered the black keys in my unit.
Once I had the keys apart I was able to determine that the conductive pads were no longer conductive. They had a resistance in the MegaOhm scale. Scratching and sanding failed to expose any new conductive surface and I was about to start sacrificing another of the Microbees for keyswitches, when I decided I couldn’t make these switches worse so I tried some radical surgery.
I took out the “conductive” pad completely and replaced it with, wait for it, some rubber I cut out of a thong. I then stuck a carefully cut piece of aluminium foil to the top and tried it. Surprisingly it worked perfectly! One of the keys is a little stiff, but the other is indistinguishable from the other keys, except for the whole “Actually works” thing.
This is not a hack I am proud of but if it works, I will live with it 😀
I want to make a joystick for it next. I have a bunch of Joystick games and no way to play them. I am impressed with the fidelity of the graphics on this system. They may be black and white, but they are a very sharp black and white.