EPROM 
erasable programmable ROM 
Unlike dynamic RAM (DRAM) and static RAM (SRAM), EPROM chips retain their data even when the computer's power is turned off. Consequently, EPROM chips are commonly used to store information essential to running a computer, such as BIOS information and basic software instructions for modems, video cards, and other peripherals. EPROMs can be erased by exposure to ultraviolet light and then reprogrammed using a device called a PROM burner.