IBM 728

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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
chars/inch	248 Chars/inch
words	6 chars (32 data bits, 1 odd parity bit, 3 end of file bits)
words/inch	41.33 Words/inch
end of record gap	0.75 Inches - 186 chars - 31 words
Tape speed	75 Inches/sec
Rewind speed	500 Inches/sec (average)
Transfer rate	18,750 Chars/sec - 3,125 Words/sec
Start time	5 Millisec
Stop time	5 Millisec
Width of tape	1/2 Inches
Length of reel	2,400 Feet
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

v • d • e

Magnetic tape data storage formats

Three Quarter Inch (19 mm)

Linear

LINCtape (1962) • DECtape (1963)

Helical

Sony DIR (19xx) • Ampex DST (1992)

Half Inch (12.65 mm)

Linear

UNISERVO (1951) • IBM 7 track (1952) • 9 track (1964) • IBM 3480 (1984) • DLT (1984) • IBM 3590 (1995) • T9840 (1998) • IBM 3592 (?) • T9940 (2000) • LTO Ultrium (2000) • T10000 (2006)