Short for Read-Only Memory, ROM is a type of "built-in" memory that is capable of holding data and having that data read from the chip, but not written to. Unlike Random Access Memory (RAM), ROM is non-volatile which means it keeps its contents regardless if it has power or not.


A good example of ROM is EEPROM, which is a programmable ROM used for the computer BIOS, as shown in the above picture.

Tip: The term ROM is used to describe any type of memory or media that is read only. For example, a CD-ROM (Compact Disc Read-Only Memory) is a disc that can only be read from and a drive only capable of reading.

Also see: EPROM, Memory terms, PROM