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IBM 726
- 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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