IBM 726

The IBM 726 was IBM's first magnetic tape unit. It was a dual magnetic tape reader/recorder developed for use with the IBM 701 and announced on May 21, 1952. This model of tape unit was shipped with the IBM 701 from December 20, 1952 until February 28, 1955.{{Cite web|url=http://www.unirecovery.com/uk/hdd/IBM_back-up-tape.htm|title=UniRecovery Fifty years of IBM innovation with information storage on magnetic tape|last=Bradshaw|first=R.|last2=Schroeder|first2=C.|date=June 10, 2003|website=www.unirecovery.com|access-date=2019-07-13}} Unlike later IBM 7 track drives, the 726 could read backwards as well as forwards.{{Citation needed|date=July 2019}}

The tape had seven parallel tracks, six for data (called a copy group, not a character) and one to maintain parity. Tapes were recorded in odd parity, to ensure at least one bit transition per

copy group as well as for error checking. [http://www.research.ibm.com/journal/rd/255/ibmrd2505ZD.pdf Innovations in the Design of Magnetic Tape Subsystems] (PDF)

The 726 concurrently handled two reels of tape, and there were two 726 units in an IBM 701 system. [https://web.archive.org/web/20050122223045/http://www-03.ibm.com/ibm/history/exhibits/701/701_1415bx26.html IBM 726 Magnetic tape reader/recorder]

class="wikitable"
Tracks | 6 Data, 1 parity
Copy groups/inch | 100 copy groups/inch
Tape speed | 75 Inches/sec
Transfer rate | 7500 copy groups/sec
End of record gap | 1 Inch - 100 chars - 16.67 words
Start time | 10 ms
Stop time | 10 ms
Width of tape | 1/2 inch
Length of reel | {{nowrap|1 200 feet}}
Composition | Cellulose acetate base