One type of permanent memory is read-only memory (ROM), also known as firmware. It is an integrated circuit programmed with specific data when it is manufactured. The types of ROM include PROM (which can be programmed once), EPROM (erasable and programmable many times), EEPROM (electrically erasable read-only memory) and flash memory (a type of EEPROM that uses in-circuit wiring to erase and rewrite data). See how EEPROM is used next.

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