The IBM 727 Magnetic Tape Unit was announced for the IBM 701 and IBM 702 on September 25, 1953. It became

IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

's standard

tape drive A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic-tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability. ...

for their early vacuum-tube era computer systems. Later vacuum-tube machines and first-generation

transistor computer A transistor computer, now often called a second-generation computer, is a computer which uses discrete transistors instead of vacuum tubes. The first generation of electronic computers used vacuum tubes, which generated large amounts of heat, w ...

s used the IBM 729-series tape drive. The 727 was withdrawn on May 12, 1971.

Overview

The tape had seven parallel tracks – six for data and one to maintain parity. Tapes with character data ( BCD) were recorded in even parity. Binary tapes used odd parity. Reflective strips were glued several feet from the ends of the tape to serve as physical beginning and end of tape markers. Write protection is provided by a removable plastic ring in the back of the tape reel. Installing the ring enables writing, thus strictly speaking, it is a write enable ring, and removing it protects the tape from being written to.

Gallery

Image:IBM_704_mainframe.gif, An

IBM 704 The IBM 704 is the model name of a large digital computer, digital mainframe computer introduced by IBM in 1954. Designed by John Backus and Gene Amdahl, it was the first mass-produced computer with hardware for floating-point arithmetic. The I ...

mainframe with IBM 727

s on the left. (image courtesy of

LLNL Lawrence Livermore National Laboratory (LLNL) is a Federally funded research and development centers, federally funded research and development center in Livermore, California, United States. Originally established in 1952, the laboratory now i ...

) File:Write protect ring.agr.jpg, Half-inch tape reel with write enable rings File:Model of IBM 727 Tape Drive (7100678957).jpg, Model of an IBM 7272 tape drive

References

727 Tape 727 {{compu-storage-stub