Read-only memory

Read-only memory (ROM) is a type of <a href="/facts/Non-volatile_memory/EN72wMD9">non-volatile memory</a> used in <a href="/facts/Computers/SQe1aK05">computers</a> and other <a href="/facts/Electronic_devices/E4JhgISq">electronic devices</a>. Data stored in ROM cannot be electronically modified after the manufacture of the <a href="/facts/Memory_device/hQKVQ51J">memory device</a>. Read-only memory is useful for storing <a href="/facts/Software/RP79lVSW">software</a> that is rarely changed during the life of the system, also known as <a href="/facts/Firmware/62UVKIUK">firmware</a>. Software applications, such as <a href="/facts/Video_game/vmTdNASJ">video games</a>, for programmable devices can be distributed as <a href="/facts/ROM_cartridge/mWLcNez7">plug-in cartridges containing ROM</a>.
Strictly speaking, read-only memory refers to hard-wired memory, such as <a href="/facts/Diode_matrix/3MPPVB8s">diode matrix</a> or a mask ROM <a href="/facts/Integrated_circuit/fjn6vg7C">integrated circuit</a> (IC), that cannot be electronically changed after manufacture. Although discrete circuits can be altered in principle, through the addition of <a href="/facts/Jump_wire/hu4Wr7rf">bodge wires</a> and the removal or replacement of components, ICs cannot. Correction of errors, or updates to the software, require new devices to be manufactured and to replace the installed device.
<a href="/facts/Floating-gate/AvmK0oBb">Floating-gate</a> ROM <a href="/facts/Semiconductor_memory/XXP0CacJ">semiconductor memory</a> in the form of <a href="/facts/Erasable_programmable_read-only_memory/kXcEca36">erasable programmable read-only memory</a> (EPROM), <a href="/facts/Electrically_erasable_programmable_read-only_memory/0yAMFY0I">electrically erasable programmable read-only memory</a> (EEPROM) and <a href="/facts/Flash_memory/Cn8JsStx">flash memory</a> can be erased and re-programmed. But usually, this can only be done at relatively slow speeds, may require special equipment to achieve, and is typically only possible a certain number of times.
The term "ROM" is sometimes used to refer to a ROM device containing specific software or a file with software to be stored in a writable ROM device. For example, users modifying or replacing the <a href="/facts/Android_operating_system/nNyHb0xz">Android operating system</a> describe files containing a modified or replacement operating system as "<a href="/facts/Custom_ROM/0zV9QDT7">custom ROMs</a>" after the type of storage the file used to be written to, and they may distinguish between ROM (where software and data is stored, usually <a href="/facts/Flash_memory/Cn8JsStx">Flash memory</a>) and RAM.
ROM and RAM are essential components of a computer, each serving distinct roles. RAM, or Random Access Memory, is a temporary, volatile storage medium that loses data when the system powers down. In contrast, ROM, being non-volatile, preserves its data even after the computer is switched off.

Read-only memory open-in-new

Read-only memory