I once spend some time on a very compact writing system that would use five of the segments of the seven segment display (not using the two vertical segments on the right) and use those for the next letter in the word. With the requirement of the characters always having at least one vertical segments that leaves you with 28 combinations, just enough to represent the 26 characters of the Latin alphabet. I was wondering if one would recognize words from the shape of the 'glued' together characters.