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
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Linear |
Three quarter inch (19 mm) |
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Half inch (12.7 mm) |
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Eight millimeter (8 mm) |
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Quarter inch (6.35 mm) |
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"Eighth" (0.15) inch (3.81 mm) |
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Stringy (1.58–1.9 mm) |
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Helical |
Three quarter inch (19 mm) |
Sony DIR (19xx) · Ampex DST (1992)
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Half inch (12.7 mm) |
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Eight millimeter (8 mm) |
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Four millimeter (3.81 mm) |
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