phototypesetting or "cold type" systems first appeared in the early 1960s and rapidly displaced continuous
casting machines like the Linotype. These devices consisted of glass disks (one per font) that spun in front of
a light source which selectively exposed characters onto light-sensitive paper. Originally they were driven by
pre-punched paper tapes. Later they were hooked up to computer front ends.
One of the earliest electronic photocomposition system was introduced by Fairchild Semiconductor. The
typesetter typed a line of text on a Fairchild keyboard that had no display. To verify correct content of the line
it was typed a second time. If the two lines were identical a bell rang and the machine produced a punched
paper tape corresponding to the text. With the completion of a block of lines the typesetter fed the
corresponding paper tapes into a phototypesetting device which mechanically set type outline printed on
glass sheets into place for exposure onto a negative film. Photosensitive paper was exposed to light through
the negative film, resulting in a column of back type on withe paper, or a galley. The galley was then cut up