A report on Magnetic-tape data storage and Group coded recording

10+1/2 in diameter reel of 9-track tape
Quarter-inch cartridges
An IBM 3590 data cartridge can hold up to 10GiB uncompressed.
Linear
Linear serpentine
Helical
IBM 729V

The first, used in 6,250 bpi magnetic tape since 1973, is an error-correcting code combined with a run length limited (RLL) encoding scheme, belonging into the group of modulation codes.

- Group coded recording

Common 7-track densities started at 200 characters per inch (CPI), then 556, and finally 800; 9-track tapes had densities of 800 (using NRZI), then 1600 (using PE), and finally 6250 (using GCR).

- Magnetic-tape data storage
10+1/2 in diameter reel of 9-track tape

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IBM 2401 System/360 tape drives that introduced the 9-track format

9-track tape

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Now generally known as 9-track tape.

Now generally known as 9-track tape.

IBM 2401 System/360 tape drives that introduced the 9-track format
Full-size reel of 9-track tape
9 Track tape drive used with DEC minicomputers
Inside a 9 Track tape drive. The vacuum columns are the two gray rectangles on the left.
Full size 1/2" tape reel in protective case
Two small 1/2" tapes, front and back
Aluminum foil strips mark the start and end of tape
The write protection ring prevents the tape from being written when removed
A typical library of half-inch magnetic tape
3M 777 High Grade 6250 CPI - Security Computer Tape

The 1⁄2 inch (12.7 mm) wide magnetic tape media and reels have the same size as the earlier IBM 7-track format it replaced, but the new format has eight data tracks and one parity track for a total of nine parallel tracks.

Various recording methods have been employed during its lifetime as tape speed and data density increased, including PE (phase encoding), GCR (group-coded recording) and NRZI (non-return-to-zero, inverted, sometimes pronounced "nur-zee").