The Daisy Wheel

A typewriter carries its letters on forty-odd steel bars, each with its own linkage back to a key, and changing the typeface means rebuilding the machine. IBM's Selectric of 1961 shrank all of it onto one golfball that tilts and rotates - eighty-eight characters you could swap in seconds - at the price of a cam train that had to solve two axes at once. David Lee at Diablo Systems asked in 1972 what happens if you use only ONE axis. Put the characters on the ends of ninety-six flexible spokes radiating from a hub, spin the right spoke into place, and hit it from behind with a solenoid hammer. The wheel is a moulded disc you can bend in your fingers, it costs almost nothing, and swapping a typeface takes about two seconds. Everything about the machine then reduces to one number: how long to turn the wheel, stop it dead, and strike. Turning is quick. Stopping is not - a wheel still ringing prints a blurred letter, so settling eats nearly half the cycle, and that is what puts every daisy wheel printer ever built between thirty and fifty-five characters a second. It is worth seeing what this machine gave up and what it kept. It cannot print a picture. It cannot print a character that is not moulded on the wheel. But because the letter is a solid shape struck through a carbon film ribbon, it prints sharper than any dot process of its day - which is exactly why the late 1970s office bought them, and exactly why they vanished the moment dots got small enough that nobody could see them.