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.

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 Millisec
Stop time	10 Millisec
Width of tape	1/2 Inches
Length of reel	1,400 Feet
Composition	cellulose acetate base

[edit] External links

• IBM 726 Magnetic tape reader/recorder
• Innovations in the Design of Magnetic Tape Subsystems (PDF)

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