(Programmable ROM) A permanent memory chip in which the content is created (programmed) by the customer rather than by the chip manufacturer. It differs from a ROM chip, which is created at the time of manufacture. PROMs are used for storage when their content is not expected to change, but in many applications, they have given way to EPROMs and EEPROMs, which can be reprogrammed. See PROM programmer, memory types and EEPROM.
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