U-matic

U-matic, also known as 3⁄4-inch Type E Helical Scan or SMPTE E, is an analog recording videocassette format developed by Sony. First shown as a prototype in October 1969 and introduced commercially in September 1971, it was among the earliest video formats to house videotape inside a cassette, replacing the reel-to-reel systems common at the time. The format uses 3⁄4-inch-wide (19 mm) tape, earning it the nickname "three-quarter-inch" or simply "three-quarter," in contrast to larger open-reel formats like 1 in (25 mm) Type C videotape and 2 in (51 mm) quadruplex videotape. The name U-matic refers to the U-shaped tape path as it threads around the video drum.

Unlike most cassette formats, U-matic's supply and take-up reels rotate in opposite directions during playback, fast-forward, and rewind—one clockwise, the other counterclockwise. Each cassette has an internal locking mechanism that secures the tape hubs during transport, and a spring-loaded door that protects the tape; this door automatically opens when the cassette is inserted into a VCR. To prevent accidental recording, cassettes came with a removable red plastic button on the bottom—removing it disabled the record function.