IBM 726

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The IBM 726 dual magnetic tape reader/recorder for the IBM 701 was announced on May 21, 1952. Unlike later IBM 7 track drives, the 726 could read backwards as well as forwards.

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. [1]

The 726 concurrently handled two reels of tape, and there were two 726 units in an IBM 701 system. [2]

Tracks 6 Data, 1 parity
Copy groups/inch 100 copy groups/inch
Tape speed 75 Inches/sec
Transfer rate 7 500 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 1 200 feet
Composition Cellulose acetate base