Inside the ATC Bunker at MMOP, a Monotype Composition Caster pauses between jobs. (It was a long pause!). The machine behind it is a
The Composition Caster reads letter-codes from the roll of tape (produced on the Monotype Keyboard), each code specifying a particular
letter. The machine positions the required matrix over the mould and pumps it full of typemetal, producing an individual "sort" (piece of type),
and then reads the next one. It can make three types per second, but must operate more slowly for larger sizes due to heat load.
When a line is complete, the tape carries the "end of line" message and the line is pulled out of the type channel and pushed into the galley.
At the same time, the message tells the caster the required spacing for the next line: each word-space will be of that width and the line will
be correctly justified.