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
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