The use of magnetic tape for data storage has been one of the constants of the computer industry.

Magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I. The recording medium was a strip of ½″ (12.7 mm) wide thin metal, consisting of nickel-plated bronze (called Vicalloy). Recording density was 128 characters per inch (198 micrometre/character) on eight tracks at a linear speed of 100 in/s (2.54 m/s), yielding a data rate of 12,800 characters per second. Of the eight tracks, six were data, one was a parity track, and one was a clock, or timing track. Making allowance for the empty space between tape blocks, the actual transfer rate was around 7,200 characters per second.



Early IBM tape drives were mechanically sophisticated floor-standing drives that used vacuum columns to buffer long u-shaped loops of tape. Between active control of powerful reel motors and vacuum control of these u-shaped tape loops, extremely rapid start and stop of the tape at the tape-to-head interface could be achieved. (1.5ms from stopped tape to full speed of up to 112.5 IPS) When active, the two tape reels thus fed tape into or pulled tape out of the vacuum columns, intermittently spinning in rapid, unsynchronized bursts resulting in visually-striking action. Stock shots of such vacuum-column tape drives in motion were widely used to represent "the computer" in movies and television.



Most late 1970's and early 1980's home computers used compact audio cassettes encoded with the Kansas City standard.

Most modern magnetic tape systems use reels that are much smaller than the old 10.5 inch open reels and are fixed inside a cartridge to protect the tape and facilitate handling. A tape drive (or "transport" or "deck") uses precisely-controlled motors to wind the tape from one reel to the other, passing a read/write head as it does. Modern cartridge formats include DAT/DDC, AIT, DLT and LTO.

Tape has quite a long data latency for random accesses since the deck must wind an average of ⅓ the tape length to move from one arbitrary data block to another. Most tape systems attempt to alleviate the intrinsic long latency, either using indexing, where a separate lookup table is maintained which gives the physical tape location for a given data block number, or by marking blocks with a tape mark that can be detected while winding the tape at high speed.

Tape remains a viable alternative to disk due to its higher bit density and lower cost per bit. Tape has historically offered enough advantage in these two areas above disk storage to make it a viable product, particularly for backup. The rapid improvement in disk storage density and price, coupled with arguably less-vigorous innovation in tape storage, has reduced the market share of tape storage products.