IBM 728
{{short description|Magnetic tape drive used on the SAGE AN/FSQ-7 computer}}
{{more sources needed|date=February 2024}}
The IBM 728 was an IBM 7 series magnetic tape drive. It was used on the SAGE AN/FSQ-7 computer. It was physically similar to the IBM 727, but with significantly different specifications.{{Cite AV media|first=Daniel|last=Faust |title=IBM 728 Magnetic Tape Drive |url=https://www.metmuseum.org/art/collection/search/307301 |year=2008|publisher=The Metropolitan Museum of Art|type=inkjet print of photograph}}
| class="wikitable" |
| 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
|{{convert|2400|ft|m|abbr=on}} |
| 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