Other secondary storage media or ideas
CD ROM - inexpensive, very high capacity, never will wear out.
DVD - technological improvement over VD ROM. Extremely high
capacity (4.7, 8.5, 9.4 or 17 GB).
CD-Recordables (CD-R) - can be recorded, but only once
CD-Rewritables (CD-RW) - can be rewritten. However, CD-RW
blanks are considerably more expensive that CD-R blanks.
Magnetic tapes - inexpensive, but very slow. Sequential access.
Wear out. Used only for backup.
Tape libraries - yet another memory hierarchy level
DRAMS instead of disks - 100 000 times faster, but 100 times more
expensive than magnetic disks.