Disk pack

The protective cover consisted of two parts, a plastic shell, with a handle in the center, that enclosed the top and sides of the disks and a separate bottom that completed the sealed package.

To remove the disk pack, the drive would be taken off line and allowed to spin down.

Turning the handle would lock the disk pack in place and free the shell for removal.

The first removable disk pack was invented in 1961 by IBM engineers R. E. Pattison[1] as part of the LCF (Low Cost File) project headed by Jack Harker.

When the removable cartridge was inserted into the cartridge drive peripheral device, the read/write heads of the drive could access the magnetic data storage surface of the platter through holes in the shell.