from
The Free On-line Dictionary of Computing (8 July 2008)
Erasable Programmable Read-Only Memory
EPROM
<storage> (EPROM) A type of storage device in which the data
is determined by electrical charge stored in an isolated
("floating") {MOS} {transistor} {gate}. The isolation is good
enough to retain the charge almost indefinitely (more than ten
years) without an external power supply. The EPROM is
programmed by "injecting" charge into the floating gate, using
a technique based on the tunnel effect. This requires higher
voltage than in normal operation (usually 12V - 25V). The
floating gate can be discharged by applying ultraviolet light
to the chip's surface through a quartz window in the package,
erasing the memory contents and allowing the chip to be
reprogrammed.
(1995-04-22)