Discusses how Morse code isn't very clear without the third (usually) unseen element, the space.
Is there a (historical?) human-optimised (vs. say, ascii or something) binary (on vs. off) code for transmitting information?
After sleeping on it, I recall one code used by Vietnam-era POWs, based on a 5x5 grid reference, optimised for decoding/learning (alphabetical order) vs. optimised for use. But, I'm not sure that it didn't also use spaces.