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To elaborate on Felipe's answer:

My father was a mathematicians, and, before the IBM Selectric typewriter, I can tell you that he bought an expensive manual German typewriter along with boxes of these plastic sticks, each with a metal head containing a math symbol. Very slow and very painful.

Later, department secretaries (there used to be more of them) would have IBM selectric typewriters, which would use a metal coated plastic ball, and you would switch the ball to get different symbols. This normally worked pretty well, except sometimes the teeth on the bottom of the ball (which was serrated for some reason) would break. This would mess up the typing action, so it would no longer type the symbol or character properly.

And even after TeX came along, there were only mainframes back then with ASCII terminals and line printers. I was one of the first people to type my thesis on TeX, and it required the following conditions: a) MIT AI lab was freely accessible by anyone (I was at Harvard, not MIT) 24 hours a day b) They had a machine running LISP and MACSYMA and wanted people to test it, so they gave out free accounts, usable only outside regular business hours, to anyone who asked c) TeX was installed on this machine d) People who worked in the MIT AI Lab would leave their offices open or unlocked, so if you walked in there in the middle of the night, you could go in there and use their Symbolics LISP machine.

The last remaining challenge was getting access to the laser printer (which was the size of a room) that was inside the locked machine room. Luckily, I had a friend (MIT math graduate student who has been mentioned and cited often on MathOverflow) whose girlfriend (now wife) is the daughter of an MIT CS professor. I asked if I could borrow the father's key to the machine room. Miraculously, the answer was yes.