ascii was designed in the 1960s for teleprinters and telegraphy, and some computing. early teleprinters were electromechanical, having no microprocessor and just enough electromechanical memory to function. they fully processed one character at a time, returning to an idle state immediately afterward, this meant that any control sequences had to be only one character long, and thus a large number of codes needed to be reserved for such controls. they were typewriter-derived impact printers, and could only print a fixed set of glyphs, which were cast into a metal type element or elements; this also encouraged a minimum set of glyphs.