A type of ROM chip that can be erased and reprogrammed. The process of programming an EPROM is often called BURNING, and the box into which it is plugged to program it an EPROM burner.
To erase its contents, the most popular and cheapest kind of EPROM has to be removed from its socket in the computer and placed under an ultraviolet light. Such UV-erasable EPROM’s have a round glass window on top of the chip package through which radiation passes and discharges the memory cells on the silicon chip. EPROM is relatively cheap and was once widely used for prototyping and to hold FIRMWARE that was subject to frequent revision. It is now being displaced by ELECTRICALLY ERASABLE PROM, which can be erased in situ by raising the voltage on one or more pins, and more recently by FLASH MEMORY.