Quad was introduced in the early 1970s, and it was, logically enough, a four channel surround format that positioned speakers in the room’s corners. Actually, quad was a group of formats; there were four incompatible LP formats, quad open reel tape, and quad tape cartridge formats. The ensuing format wars dulled the public’s interest in quad, and it faded away in the late ‘70s. Today’s 5.1 surround origins can be traced back to analog film formats used in cinemas from the early 1950s to the late 1990s. Dolby Digital 5.1 is an integral part of DVD video format – the most successful surround system of all time. DVD-Audio and the Super Audio CD have adapted, with some minor differences, home theater’s 5.1 speaker array. Chesky Records created a music oriented 6.0 surround format.