An Erasable Programmable Read-Only Memory (EPROM)

An Erasable Programmable Read-Only Memory (EPROM) is a type of early semiconductor storage device that uses an ultraviolet (UV) light for erasure.

A major disadvantage of the earlier PROM technology was that if the burn process were to fail, then it would be necessary to discard the chip. In any case, it could be used only once and never reused for anything else again. To overcome this limitation, Intel pioneered the erasable PROM (EPROM), which employed charge-storage MOS technology. The chip came with a window that permitted light to expose the die substrate. Since ultraviolet (UV) light is a rich source of high-energy photons, exposing the die to it resulted in memory erasure.