TRS 80 Model 1 Question

The latter _must_ be a contact problem (the 2 '2' keys, on the main part and the number pad, are just wired in parallel), the former almost certainly is too (it could be a very strange ROM error, but I think we can ignore that for now). The M1/3/4 keyboards are electrically a matrix of switches. They're scanned by the CPU address lines (!), suitably buffered. The outputs go to the data lines, also via buffers. A chip fault will take out an entire row or column of the matrix. I am not sure what sort of keyboard you have. Old model 1s have the leaf spring switches, like on a VT100 or HP85. With those you can pull the keycaps, plungers and springs and if necessary desolder individual contacts. Often, though, just pulling the keycaps and cleaning things cures problems. M3s, M4s, and I believe later M1s have indidual keyswitches (and I think there are at least 2 flavours). You can pull the keycaps, desolder the switch pins from the PCB, and then unclip the switch from the frame. The switch then comes apart for cleaning. Some of them use conductive rubber contacts -- if you can't get this type to work, rub a very soft pencil (a 6B if yo can get one) over the rubber contact inisde the rubber dome. I had to do this to my M4 keyboard. I then moved the dubious switches to the number pad, since I never use that area. That way I had all good swtichs on the main part of the keyboard... -tony