We got lots done with 6-bit pre-ASCII encodings, actually, like CDC Display Code and Univac's Fieldata. It's more than enough for 26 letters, 10 digits, and lots of punctuation. And there are faint echoes of these early character sets remaining in ASCII -- a zero byte is ^@, for example, because @ was the zero-valued Fieldata "master space" character, which distinguished EXEC 8 control cards from source code and data cards.