It really began shortly after the end of World War II, when two Frenchmen, Higonnet and Moyrou, developed a viable phototypesetter that used a strobe light and a series of optics to project characters from a spinning disk onto photographic paper.
They licensed their patents to a Massachusetts firm called Photon, which began producing a series of very expensive phototypesetting machines in 1945.
Photon grew to be a major firm, with sales and service offices all over the country.
The machines made by Photon, and the competitors who began to appear, were operated by punched paper tape produced on special “perforators,” that had been used for some lead casting machines since 1932.
The paper tape used a 6-level code called TTS (teletypesetting).
Because you can only represent about 36 different characters in six bits, it had to use shift, super-shift, and “bell” characters to get upper and lower case alphabets, numerics, punctuation and special characters.
They had large keyboards with all of the special typesetting commands like “quads”, em-space, en-space, en-dash, em-dash, open and close double and single quotes, and some pi characters like bullets and stars.
At first the skill required to prepare these tapes was little changed from the lead casting machines; the operator controlled the line breaks, based on line lengths shown on a line width counter and his knowledge of hyphenation rules and conventions.