Spots were read and written with an optical mechanism with an access time of ca.
[2] The optical system consisted of a cathode ray tube that functioned as a flying-spot scanner, the source of light beams produced on its face and focused onto the photographic plates with a system of lenses.
The light beam could be split into several components to read multiple plates simultaneously, permitting the formation of a group of bits for each location.
[3] A flying-spot store was the main permanent program and data memory for the first electronic central office installed on a trial basis in Morris, Illinois in 1960.
For temporary data, the system used a barrier-grid electrostatic storage tube.