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IT Support & Hardware · Foundational

Read-Only Memory (ROM)

Non-volatile memory that retains data without power; on PCs it historically stored firmware.

Definition

ROM retains contents when power is off. Modern firmware is stored in flash memory (EEPROM), which can be updated, so the term 'BIOS ROM' persists even though it is rewritable. ROM differs from RAM in volatility and purpose.

Example

Motherboard firmware is stored on an SPI flash chip often called the BIOS ROM.

Exam tip

ROM is non-volatile; RAM is volatile.

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