The original format for magnetic tape sound reproduction was reel-to-reel audio tape recording, first made available in the 1940s. However, the machines were bulky, and the reels themselves were more difficult to handle than vinyl records. Born from the desire to have an easier to use tape format, the enclosed reel mechanism was introduced in the mid 1950s.
The original cartridge format had four monaural or two pairs of stereo tracks. When the foil tape passed across a pair of contacts close to the read head, it signaled the player to switch to the next program track, allowing the cartridge to play continuously with no re-winding, though there was usually a short gap in the music at the join in the tape. The playing time was later doubled by recording four stereo tracks on the tape, although this made each track half as wide, reducing the sound quality. This design was dubbed "8-track" to distinguish it from the original format, which then became a "4-track cartridge" by back-formation.
The popularity of both 4-track and 8-track cartridges grew from the booming automobile industry. In 1965, Ford Motor Company introduced built-in 8-track players as a custom option. By 1966, all of their vehicles offered this upgrade. Thanks to Ford's backing, the 8-track format eventually won out over the 4-track format.
Despite mediocre audio quality and the problems of fitting a standard vinyl LP album onto a four-program cartridge, the format gained steady popularity due to its convenience and portability. Home players were introduced in 1967. With the availability of cartridge systems for the home, consumers started thinking of 8-tracks as a viable alternative to vinyl records, not just as an automobile convenience. Within the year, prerecorded releases on 8-track began to come along at nearly the same time as the vinyl releases.
However, another format was just beginning to appear: the compact audio cassette, less than a quarter of the size of the 8-track cartridge. The 8-track cartridge had merely set the stage for the handier, recordable cassette.
8-track players still remained a common feature in homes and automobiles until the early 1980s, slowly fading into obscurity. By the time the compact disc arrived in the late 1980s, the 8-track had all but vanished, found mostly among collectors. The 4-track cartridge was also still used at some radio stations.
See Also: PlayTape, Compact audio cassette, List of audio formats.