read-only memory

computing

Also known as: ROM

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July 23, 2026

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Read-only memory (ROM) is a type of computer memory that stores data that cannot be modified during normal computer operation. This is in contrast to random-access memory (RAM), which can be read from and written to by the central processing unit (CPU). ROM is a form of primary memory, directly accessible by the CPU.1

ROM is used for essential programs that are fundamental to a computer's operation, such as the bootstrap program that initiates the computer and loads its operating system, or the BIOS (basic input/output system) that manages external devices. While ROM is not rewritable once manufactured, some types like EPROM, EAROM, and flash memory allow for rewriting, though this process is much slower than reading.2

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computer memory
Semiconductor memory
Some nonvolatile memories, such as read-only memory (ROM), are not rewritable once manufactured or written. Each memory cell of a ROM chip has either a transistor for a 1 bit or none for a 0 bit. ROMs are used for programs that are essential parts of a computer’s operation, such…
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Some nonvolatile memories, such as read-only memory (ROM), are not rewritable once manufactured or written. Each memory cell of a ROM chip has either a transistor for a 1 bit or none for a 0 bit. ROMs are used for programs that are essential parts of a computer’s operation, such…
Read More