IBM 728

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
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
Magnetic tape data storage formats
Linear
Three quarter inch (19 mm)
  • TX-2 Tape System (1958)
  • LINCtape (1962)
  • DECtape (1963)
Half inch (12.7 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)
  • 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)
  • KC standard, Compact Cassette (1975)
  • HP DC100 (1976)
  • Tarbell Cassette Interface (1977)
  • Commodore Datasette (1977)
  • DECtapeII (1979)
Stringy (1.58–1.9 mm)
  • Exatron Stringy Floppy (1979)
  • ZX Microdrive (1983)
  • Rotronics Wafadrive (1984)
Helical
Three quarter inch (19 mm)
  • Sony DIR (19xx)
  • Ampex DST (1992)
Half inch (12.7 mm)
  • 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)