PROMs

PROM (Programmable Read-Only Memory) is a type of non-volatile memory (meaning that its data is retained even after power is turned off) which can be programmed only once. Once programmed, it cannot be erased or reprogrammed. So it is used to store permanent information. Unlike standard ROM devices which get programmed during manufacturing, PROM can be custom programmed by user according to requirement. PROMs are often called as OTP (One time programmable) ROMs. PROM is less expensive than standard ROM devices.