from
The Free On-line Dictionary of Computing (8 July 2008)
write protect
<storage> A feature of certain {removable media} storage
devices that tells the system whether or not it should allow
the data on the media to be modified. Write protecting an
item of media prevents accidental overwriting of valuable
data.
For example, the write protect tab on a 3.5-inch {floppy
disks} is a small sliding plastic square that can either cover
or expose a hole near the edge of the disk cover. The drive
wil only allow the disk to be written to if the hole is
closed.
(2007-03-24)