IBM 7340 Hypertape
Drive
- Model 1 announced October 23, 1961 and withdrawn
May 12, 1971
- Model 2 announced April 9, 1963 and withdrawn February
8, 1971
- Model 3 announced April 7, 1964 and withdrawn January
30, 1968
IBM began an effort in the summer of 1960 to develop
greatly superior tape storage units using one-inch wide
tape. Such a product was announced in October 1961 with
the roll-out of the IBM 7340 Hypertape Drive and the
IBM 7640 Hypertape Control Unit.
The Hypertape system offered the highest data rate
then available in the industry: 170,000 characters per
second at a tape speed of 112.5 inches per second. The
drive's single capstan was able to accelerate the tape
from stop to full speed in only 2.5 milliseconds. Initially,
the 7340 was connected to the IBM 7074 Data Processing
System using the IBM 7907 Data Channel and IBM 7640.
As many as ten 7340 Hypertape Drives could be connected
with each 7907 channel.
Among the 7340's features were:
- Character rate -- As many as 340,000 decimal digits
per second; 170,000 alphanumeric characters per second.
- Checking -- Error detection and correction, dual
odd-parity checking. A new, highly reliable method
of recording called "IBM Phase Encoding"
was used.
- Reel Capacity -- In many applications, more than
twice that of the IBM 729-IV reels (recorded at high
density).
- Cartridges for Tape Reels -- Supply and take-up
reels in a sealed cartridge; faster loading and unloading
(no manual threading of tape), tape protected from
contamination and operator damage, unload reel without
rewinding at any point in the file.
- Read Backward -- No rewinding necessary between
passes in Phase II of tape sorting, faster tape searching.
- Faster Access Times -- 4.2 milliseconds (average).
- File Protection -- Cartridge file protect device
was under program control.
The Hypertape system used two-reel cartridges for ease
of handling and tape protection. The cartridge was 17
inches long, 10.2 inches high (including the handle)
and 2.2 inches wide. Once mounted, the tape was automatically
loaded. It was drawn out of the cartridge so as to pass
by the read-write head, leaving slack in either side
of the head in the form of a tape loop in two vertical
vacuum columns. Automatic tape loading was performed
in less than 10 seconds.
First deliveries of the Model 1 Hypertape drives and
control units were made to the National Revenue Service
of Canada in May 1963.
Prior to the 7340's announcement, IBM had began a project
to provide a similar product for smaller computers.
The data rate was reduced from 170,000 to 34,000 characters
per second, and only single channel operation was provided.
The resultant Model 2 was introduced in April 1963,
just two days after the debut of the celebrated System/360.
It was never shipped outside IBM and was withdrawn from
marketing in February 1971.
A new Model 3 of the 7340 was developed to provide
a double-density option of 3022 bytes per inch, in addition
to the 1511 bytes per inch of the Models 1 and 2, thereby
doubling the data rate to 340,000 bytes per second.
The Model 3 was announced in April 1964, and the first
customer shipment went to the U.S. Internal Revenue
Service in West Virginia in mid-1965. A second unit
was shipped to the Boeing Company in Seattle. Although
both customers received good performance from their
Hypertape units, the 7340 did not enjoy widespread acceptance
elsewhere because many potential customers did not wish
to incur the costs of converting existing half-inch
tape libraries to Hypertape.
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