IBM 726
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 |
External link
| Magnetic tape data storage formats | ||
|---|---|---|
| Linear | Helical-Scan | |
| Three Quarter Inch (~19 mm) |
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| Half Inch (12.65 mm) |
UNISERVO (1951) - IBM 7 Track (1952) - 9 Track (1964) - IBM 3480 (1984) - DLT (1984) - IBM 3590 (1995) - T9840 (1998) - T9940 (2000) - LTO Ultrium (2000) - T10000 (2006) |
Redwood SD-3 (1995) - DTF (19xx) - SAIT (2003) |
| Eight Millimeter (8 mm) |
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| Quarter Inch (6.35 mm) |
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| Eighth Inch (3.81 mm) |
KC Standard, Compact Cassette (1975) - DC100 (1976) - Commodore Datassette (1977) - DECtapeII (1979) |
DDS/DAT (1989) |
| Stringy (1.58 - 1.9 mm) |
Exatron Stringy floppy (1979) - ZX Microdrive (1983) - Rotronics Wafadrive (1984) |
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