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. Unlike later IBM 7 track drives, the 726 could read backwards as well as forwards.
The tape had seven parallel tracks, six for data 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.
The 726 concurrently handled two reels of tape, and there were two 726 units in an IBM 701 system.
Tracks6 Data, 1 parity
Copy groups/inch100 copy groups/inch
Tape speed75 Inches/sec
Transfer rate7500 copy groups/sec
End of record gap1 Inch - 100 chars - 16.67 words
Start time10 ms
Stop time10 ms
Width of tape1/2 inch
Length of reel
CompositionCellulose acetate base