Read-Only Memory

read-only memory

[′rēd ¦ōn·lē ′mem·rē]

(computer science)

A device for storing data in permanent, or nonerasable, form; usually a static electronic or magnetic device allowing extremely rapid access to data. Abbreviated ROM. Also known as read-only storage.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Read-Only Memory

(storage)

(ROM) A type of data storage device which is manufactured with fixed contents. In its most general sense, the term might be used for any storage system whose contents cannot be altered, such as a gramophone record or a printed book; however, the term is most often applied to semiconductor integrated circuit memories, of which there are several types, and CD-ROM.

ROM is inherently non-volatile storage - it retains its contents even when the power is switched off, in contrast to RAM.

ROM is often used to hold programs for embedded systems since these usually have a fixed purpose. ROM is also used for storage of the lowest level bootstrap software (firmware) in a computer.

See also Programmable Read-Only Memory.

This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

ROM

(1) Firmware for an Android phone. See Android ROM.

(2) (Read Only Memory) A memory chip that permanently stores instructions and data. Also known as "mask ROM," its content is created in the last masking stage of the chip manufacturing process and cannot be changed. Stand-alone ROM chips and a ROM bank in microcontrollers are used to hold control routines for myriad applications. ROMs were also widely used to hold the BIOS in early PCs as well as plug-in cartridges for video games. See microcontroller.

Although EPROMs, EEPROMs, and particularly flash memory, are the kinds of non-volatile storage one hears about more often, ROM is a mature, inexpensive technology that is easy to integrate into the design of any CMOS chip.

ROMs Are Secure
Unlike flash memory, which can be updated, the data in ROM chips cannot be tampered with. If encryption keys and other security codes are stored in a ROM, they cannot be altered unless the chip is physically replaced (see secure boot). See ROM BIOS, memory types, RAM, EEPROM and flash memory.

ROMs Are Everywhere

Cartridges that contain nothing more than a ROM chip are used to hold games and educational programs. The yellow ROM cartridge in this image (bottom right) contains a program for the LeapPad Learning System for preschoolers.

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