magnetic tape

Narrow plastic ribbon coated with an easily magnetizable material on which data can be recorded. It is used in sound recording, audio-visual systems (videotape), and computing. For mass storage on commercial mainframe computers, large reel-to-reel tapes are still used, but cartridges are becoming popular. Various types of cartridge are now standard on minicomputers and PCs, while audio cassettes were used with early home computers.

Magnetic tape was first used in sound recording in 1947, and made overdubbing possible, unlike the direct-to-disc system it replaced. Two-track tape was introduced in the 1950s and four-track in the early 1960s; today, studios use 16-, 24-, or 32-track tape, from which the tracks are mixed down to a stereo master tape.

In computing, magnetic tape was first used to record data and programs in 1951 as part of the UNIVAC 1 system. It was very popular as a storage medium for external memory in the 1950s and 1960s. Since then it has been largely replaced by magnetic disks as a working medium, although tape is still used to make back-up copies of important data. Information is recorded on the tape in binary form, with two different strengths of signal representing 1 and 0.