Alesis Digital Audio Tape (ADAT) is a digital audio recording format and interface definition developed by the Alesis company in the early 1990s. The original ADAT format has eight digital audio tracks and used S-VHS tapes. The sampling rate was 48 kHz, and the sample depth was 16 bits. For the transmission of the eight data channels, the ADAT system uses optical transmission via TOSlink.
Instead of the classic recording medium, Alesis relies on hard disk drives in more recent developments and has increased the number of tracks and the sample depth to 24 each. Furthermore, the sampling rate of 44.1 kHz used in compact discs was additionally introduced.