Digital Audio Tape

Digital Audio Tape (DAT or R-DAT) is a discontinued digital recording and playback medium developed by Sony and introduced in 1987. In appearance it is similar to a Compact Cassette, using 3.81-millimetre (0.150 in), commonly referred to as four-millimitre, magnetic tape enclosed in a protective shell, but it is roughly half the size at 73 mm × 54 mm × 10.5 mm. The recording is digital rather than analog. DAT can record at sampling rates equal to, as well as higher and lower than, that of a CD (44.1, 48, and 32 kHz respectively) at 16 bits.

Similar to most formats of videocassette, a DAT cassette may only be recorded and played in one direction, unlike an analog compact audio cassette. Many DAT recorders had the capability to embed program numbers and IDs into the recording, which can be used to select an individual track, like on a CD player.

Although intended as a replacement for analog audio compact cassettes, the format was never widely adopted by consumers because of its expense, as well as concerns from the music industry about unauthorized high-quality copies. If a comparable digital source is copied without returning to the analogue domain, then the DAT will produce an exact clone, unlike other digital media such as Digital Compact Cassette or non-Hi-MD MiniDisc, both of which use a lossy data-reduction system.