A type of
magnetic disk, or possibly
magneto-optical disk which is not permanently attached to
the
disk drive (not a
fixed disk) but which can be taken
out and replaced, allowing many disks to be used in the same
drive.
The term "removable disk" would seem to be applicable to
floppy disks but is generally reserved for hard disks in
suitable cartridges such as those made by
Syquest,
Iomega
and others.
Removable disk packs were common on minicomputers such as
the
PDP-11 in use in the 1970s except that the drives were
the size of washing machines and the disk packs as big as
car wheels. Removable disks became popular on
microcomputers in the 1990s as a cheap way of expanding disk
space, transporting large amounts of data between computers
and storing backups. Large, cheap fixed hard disks and USB memory sticks have made removable disks less attractive.