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The IBM 726 was formally announced on May 21, 1952.
Magnetic tapes used with the 701 Data Processing System provided a high-speed method of
introducing and recording greater masses of data than were possible through either cathode
ray tube or drum storage. The magnetic tape could read or write at a rate of 12,500 digits
a second and had a capacity in excess of 2 million digits a tape. It was used as an output
unit to provide large-capacity storage for programs and data or as a high-speed input unit
for information previously recorded on a reel of magnetic tape.
The tape used by the 726 was an oxide-coated, non-metallic tape, approximately a
half-inch wide. Information was recorded on the tape in six channels that ran parallel to
the length of the tape. A seventh channel on the tape served to check the reading and
writing of the other six channels by an odd-number redundancy check. The tape density was
100 bits per linear inch. Tapes could be interchanged between different 726 units. Two
1,200-foot and two 200-foot reels of magnetic tape were furnished as standard.
Reading and recording data on magnetic tapes was intermittent, making high-speed starting
and stopping an essential capability of the reader/recorder. Through a unique control
system developed for the 726, a tape reached full speed in 1/100th of a second, or before
moving half an inch.
The 726 could handle two reels of tape simultaneously, and there were two 726 units in the
701 system. It rented for $850 a month.
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