What is Read-only memory?
{{redirect|ROM}} [[File:6540 ROM chip.jpg|thumb|An image of a ROM chip, this particular one being a [[Commodore PET]].]] '''Read-only memory''' (or simply '''ROM''') is a type of [[computer memory]]. Unlike [[RAM]], it keeps its contents even when the [[computer]] or device is turned off. Usually, ROM cannot be written to when the computer runs normally. ROM is used for the [[BIOS]] which tells the computer how to start, or important programs like the [[firmware]] of certain devices, which usually does not need to be modified. Usually, ROM comes on [[computer chip]]s. There are different kinds of ROMs: * [[Masked ROM]]: This kind is written once, at the [[factory]]. It cannot be changed at all later on. Its main benefit is that it is very cheap to make. * [[PROM]]: Can be programmed once. Comes ''unprogrammed'' from the factory. Programming consists in removing connections. Invented in 1956, it has been replaced by EPROMs. * [[EPROM]]: This kind can be erased with [[UV]] light. Invented in 1972, it became rare early in the 21st century.<ref>{{Cite web|url=https://www.eetimes.com/document.asp?doc_id=1125035|title=Sun setting on EPROM Market?|last=McKeefry|first=Hailey Lynn|date=2000-03-27|website=EETimes}}</ref> * [[EEPROM]]: This kind can be erased using an [[electricity|electrical]] signal. Today, [[flash memory]] is often used.'' ==References== {{reflist}} {{Tech-stub}} [[Category:Computer memory]] [[Category:Computer science]]