Digitally recorded audio tape produced in cassettes that can carry up to two hours of sound on each side and are about half the size of standard cassettes. DAT players/recorders were developed in 1987. Pre-recorded cassettes are copy-protected.
The first DAT for computer data was introduced in 1988.
DAT machines are constructed like video cassette recorders (though they use metal audio tape), with a movable playback head, the tape winding in a spiral around a rotating drum. The tape can also carry additional information; for example, a time code for instant location of any point on the track. The music industry delayed releasing pre-recorded DAT cassettes because of fears of bootlegging, but a system has now been internationally agreed whereby it is not possible to make more than one copy of any pre-recorded compact disc or DAT. DAT is mainly used in recording studios for making master tapes. The system was developed by Sony.
By 1990, DATs for computer data had been developed to a capacity of around 2.5 gigabytes per tape, achieved by using helical scan recording (in which the tape covers about 90% of the total head area of the rotating drum). This enables data from the tape to be read over 200 times faster than it can be written. Any file can be located within 60 seconds. By 2004, the storage capacity of DAT tapes reached over 240 gigabytes per tape, and they had become popular as an alternative backup system for computer data to recordable CD-ROMs.