IBM 728

Magnetic tape drive used on the SAGE AN/FSQ-7 computer

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The IBM 728 magnetic tape drive was used on the SAGE AN/FSQ-7 computer. It was physically similar to the IBM 727, but with significantly different specifications.

This is one of several IBM 7 track tape drives.

tracks  | 6 Data, 1 synchronization

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char/inch  | 248 char/inch
words  | 6 chars (32 data bits, 1 odd parity bit, 3 end of file bits)
word/inch  | 41.33 word/inch
end of record gap  | 0.75 inch - 186 chars - 31 words
Tape speed  | 75 inch/s
Rewind speed  | 500 inch/s (average)
Transfer rate  | 18,750 char/s - 3,125 word/s
Start time  | 5 ms
Stop time  | 5 ms
Width of tape  | 1/2 inch
Length of reel  | 2,400 ft (730 m)
Composition  | Mylar or cellulose acetate base

Tape Word Bit Positions

-->   Tape travel
LS   L6   L12  R2   R8   R14
L1   L7   L13  R3   R9   R15
L2   L8   L14  R4   R10  P
SYN  SYN  SYN  SYN  SYN  SYN
L3   L9   L15  R5   R11  EOF
L4   L10  RS   R6   R12  EOF
L5   L11  R1   R7   R13  EOF

-->   Tape travel

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Magnetic-tape data storage formats

Linear|

| Wide (19–25.4 mm)|

* IBM 7340 (1961)
* LINCtape (1962)
* DECtape (1963)
* CDC 626 (1966)

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Half inch (12.7 mm)|

* UNISERVO (1951)
* IBM 7-track (1952)
* TX-2 Tape System (1958)
* 9-track (1964)
* IBM 3480 (1984)
* DLT (1984)
* IBM 3590 (1995)
* T9840 (1998)
* T9940 (2000)
* LTO Ultrium (2000)
* IBM 3592 (2003)
* T10000 (2006)

Eight millimeter (8 mm)|

* Travan (1995)
* IBM 3570 MP (1997)
* ADR (1999)

Quarter inch (6.35 mm)|

* QIC (1972)
* SLR (1986)
* Ditto (1992)

"Eighth" (0.15) inch (3.81 mm)|

* D/CAS (1971)
* KC standard, Compact Cassette (1975)
* DC100 (1976)
* Tarbell Cassette Interface (1976)
* Commodore Datasette (1977)
* DECtape II (1979)
* IBM PC Cassette (1981)

Stringy (1.58–1.9 mm)|

* Exatron Stringy Floppy (1979)
* ZX Microdrive (1983)
* QL Microdrive (1984)
* Rotronics Wafadrive (1984)

Helical|

| Three quarter inch (19 mm)|

* Sony DIR (19xx)
* Ampex DST (1992)

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Half inch (12.7 mm)|

* ArVid (1992)
* Redwood SD-3 (1995)
* DTF (19xx)
* SAIT (2003)

Eight millimeter (8 mm)|

* Data8 (1987)
* Mammoth (1994)
* AIT (1996)
* VXA (1999)

Four millimeter (3.81 mm)|

* DDS/DAT (1989)

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