i guess you'd discover that protocol by playing with a yaroze/caetla/etc with some of of device listening in between and recording the words? never really got

i guess you'd discover that protocol by playing with a yaroze/caetla/etc with some of of device listening in between and recording the words? never really got into using the parallel port as a cheap dio until building science rigs years later... (and some fun experiments with using it to do cheap adc when in college)