History (1964): 9-Track Tape

This article was published by the Museum of Obsolete Media.

9-track tape (1964-2003)

9-track computer tape was introduced in 1964 for use with the IBM System/360, replacing 7-track tape.

The tape itself is half-inch wide, with 8 data tracks and one parity track, all parallel.

To load a tape, the protective ring is removed from the outside of the tape reel, and the reel installed on the supply hub. The tape leader is then threaded through the various roller assemblies and onto the take-up reel.

In most drives, a vacuum system provided a physical buffer by storing a short length of tape in the vacuum column under relatively low tension, to avoid damage or stretching of the tape due to tape snatch.

Tapes included an end-of-tape (EOT) foil strip. When EOT was encountered, the unit would either halt or rewind the tape onto the supply reel.

9-track tapes commonly had densities of 800, 1,600, and 6,250cpi, giving approximately 20MB, 40MB and 140MB respectively on a standard 2,400 feet (730m) reel.

It was used for over 30 years, but drive production ceased in 2003, tape production having ended in 2002.