© Science Museum/Science and Society Picture Library
Until the mid-1950s there was no effective way of recording television signals, and the vast majority of programmes were broadcast live. This constrained both the format and, in the case of sporting fixtures, the transmission time of programmes. Television performances were ephemeral, and few survive in any recorded form. The invention of the videotape recorder, by engineers at Ampex in 1956, therefore revolutionised television. It started the transition to the current practice, in which virtually all programmes are pre-recorded and edited before transmission.
The Radio Corporation of America (RCA) had demonstrated an experimental videotape recorder in 1953, which eloquently demonstrated the core problem: there is so much information in a television signal that it took one and a half miles of tape to record just four minutes.
The machine invented by Charles Ginsburg and his team at Ampex overcame the obstacle by using rapidly-rotating recording heads to 'scan' across the width of tape, laying down a succession of overlapping 'stripes' of recorded material moving at the comparatively slow rate of 15 inches per second. With this system a 10-inch spool of 2-inch-wide tape could carry 1 hour of television.