Until the 1980s, most commercial audio recordings were made according to analog principles, with the original sound modulated onto another medium, the physical characteristics of which are directly related to the original sound. In contrast, digital recording sees the original sound converted to digital information and stored as a series of 1s and 0s—known as "bits."
Although the principles of digital recording were already in place in the late 1930s, it was not until 1975 that a usable commercial system was developed, when Dr. Thomas Stockham (1933-2004) established Soundstream, Inc., the first dedicated digital recording company. The original audio was passed through an Analog-Digital-Converter (ADC), converted to 16-bit audio, and stored on a 1-inch (2.54 cm) Honeywell tape deck. To play back the sound, the digital information was passed through a Digital-Analog- Converter (DAC). The system offered the highest quality sound without any of the problems of analog recording. Mechanical deficiencies commonly associated with analog equipment were also radically improved.
Competing systems, such as those produced by 3M, Sony, and JVC appeared in quick succession, but for the rest of the decade it was Stockham's system that dominated. From the early 1980s, the Sony DASH and Mitsubishi ProDigi formats rendered previous systems obsolete. At the same time, Sony's DAT cassette format became the de facto standard for making digital stereo recordings. All of these formats remained in use until the early 1990s, after which hard disk recording began its gradual domination.
