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Read-Only Memory (ROM)

Vangie Beal
Last Updated June 23, 2021 7:06 am

Pronounced rahm, a read-only memory (ROM) is a computer memory on which data has been pre-recorded. Once data has been written onto a ROM chip, it cannot be removed and can only be read. Unlike main memory (RAM), ROM retains its contents even when the computer is turned off. ROM is referred to as being non-volatile, whereas RAM is considered volatile. Read more about the difference between RAM and ROM here.

Most personal computers contain a small amount of ROM for critical programs that will not need to change over a device s lifetime, known as firmware. In addition, ROMs are used extensively in calculators and peripheral devices such as laser printers, whose fonts are sometimes stored in ROMs.

Three Types of ROM

There are three types of ROM that have historically been used in PCs, with each subsequent version replacing its predecessor: