EPROM, form of computer memory that does not lose its content when the power supply is cut off and that can be erased and reused. EPROMs are generally employed for programs designed for repeated use but that can be upgraded with a later version of a program. EPROMs are erased with ultraviolet light. The capabilities of EPROMs were extended with EEPROM (electrically erasable programmable read-only memory); flash memory, which is extensively used in computers in the early 21st century, is an EEPROM.