spangler@brl-tgr.ARPA (James J. Spangler ) (09/25/84)
I have been expermenting with zx81's and find that using a 8255 I/O chip is the best way for me. It has 24 I/O lines that can drive a 5 volt logic level, which can be used to drive leds, scr's, and triac's. Besides using the 8255 you would need address decoders, which can be done with a 74LS138 and a few other 74's. I have also tried voice interfacing using the GE SP-0256 which seems to work well. Jim