# Firmware

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Low-level computer software

Firmware is commonly stored in an [EEPROM](/source/EEPROM) or Flash memory,[1] which makes use of an I/O protocol such as [SPI](/source/Serial_Peripheral_Interface).

In [computing](/source/Computing), **firmware** is [software](/source/Software) that provides [low-level](/source/Low-level) control of [computing device](/source/Computing_device) [hardware](/source/Computer_hardware). For a relatively simple device, firmware may perform all control, monitoring and data manipulation functionality. For a more complex device, firmware may provide relatively low-level control as well as [hardware abstraction](/source/Hardware_abstraction) [services](/source/Service_(systems_architecture)) to higher-level software such as an [operating system](/source/Operating_system).

Firmware is found in a wide range of computing devices, including [personal computers](/source/Personal_computer), [smartphones](/source/Smartphone), [home appliances](/source/Home_appliances), [vehicles](/source/Vehicles), [computer peripherals](/source/Computer_peripherals) and in many of the [integrated circuits](/source/Integrated_circuit) inside each of these larger systems.

Firmware is stored in [non-volatile memory](/source/Non-volatile_memory) – either [read-only memory](/source/Read-only_memory) (ROM) or programmable memory such as [EPROM](/source/EPROM), [EEPROM](/source/EEPROM), or [flash](/source/Flash_memory). Changing a device's firmware stored in ROM requires physically replacing the memory chip – although some chips are not designed to be removed after manufacture. Programmable firmware memory can be reprogrammed via a procedure sometimes called *flashing*.[2]

Common reasons for [changing](/source/Patch_(computing)) firmware include fixing [bugs](/source/Bug_(engineering)) and adding [features](/source/Feature_(software_design)).

## History and etymology

Ascher Opler used the term *[firmware](https://en.wiktionary.org/wiki/firmware)* in a 1967 *[Datamation](/source/Datamation)* article, as an intermediary term between *hardware* and *software*. Opler projected that [fourth-generation computer](/source/Fourth-generation_computer) systems would have a [writable control store](/source/Writable_control_store) (a small specialized high-speed memory) into which [microcode](/source/Microcode) firmware would be loaded. Many software functions would be moved to microcode, and [instruction sets](/source/Instruction_set) could be customized, with different firmware loaded for different instruction sets.[3]

As computers began to increase in complexity, it became clear that various programs needed to first be initiated and run to provide a consistent environment necessary for running more complex programs at the user's discretion. This required programming the computer to run those programs automatically. Furthermore, as companies, universities, and marketers wanted to sell computers to laypeople with little technical knowledge, greater automation became necessary to allow a layperson to easily run programs for practical purposes. This gave rise to a kind of software that a user would not consciously run, and it led to software that a lay user would not even know about.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

As originally used, firmware contrasted with hardware (the CPU itself) and software (normal instructions executing on a CPU). It was not composed of CPU machine instructions, but of lower-level microcode involved in the implementation of machine instructions. It existed on the boundary between hardware and software; thus the name *firmware*. Over time, popular usage extended the word *firmware* to denote any computer program that is tightly linked to hardware, including [BIOS](/source/BIOS) on PCs, [boot firmware](/source/Boot_firmware) on smartphones, [computer peripherals](/source/Computer_peripheral), or the control systems on simple [consumer electronic devices](/source/Consumer_electronic_devices), such as [microwave ovens](/source/Microwave_oven) and [remote controls](/source/Remote_control).

## Applications

### Computers

ROM [BIOS](/source/BIOS) firmware on a [Baby AT](/source/Baby_AT) [motherboard](/source/Motherboard)

In some respects, the various firmware components are as important as the [operating system](/source/Operating_system) in a working computer. However, unlike most modern operating systems, firmware rarely has a well-evolved automatic mechanism of updating itself to fix any functionality issues detected after shipping the unit.

A computer's firmware may be manually updated by a user via a small utility program. In contrast, firmware in mass storage devices (hard-disk drives, optical disc drives, flash memory storage e.g., solid state drive) is less frequently updated, even when flash memory (rather than ROM, EEPROM) storage is used for the firmware.

Most computer peripherals are themselves special-purpose computers. Devices such as printers, scanners, webcams, and [USB flash drives](/source/USB_flash_drive) have internally-stored firmware; some devices may also permit field upgrading of their firmware. For modern, simpler devices, such as [USB keyboards](/source/USB_keyboard), [USB mouses](/source/USB_mouse) and [USB sound cards](/source/USB_sound_card), the trend is to store the firmware in on-chip memory in the device's [microcontroller](/source/Microcontroller), as opposed to storing it in a separate [EEPROM](/source/EEPROM) chip.

Examples of computer firmware include:

- The [BIOS](/source/BIOS) firmware used on PCs

- The [(U)EFI](/source/Unified_Extensible_Firmware_Interface)-compliant firmware used on [Itanium](/source/Itanium) systems, Intel-based [Macs](/source/Mac_(computer)), and many newer PCs

- [Hard disk drive](/source/Hard_disk_drive), [solid-state drive](/source/Solid-state_drive), [optical disc drive](/source/Optical_disc_drive) and optical disc recorder firmware[4]

- [Video BIOS](/source/Video_BIOS) of a [graphics card](/source/Graphics_card)

- [Open Firmware](/source/Open_Firmware), used in [SPARC](/source/SPARC)-based computers from [Sun Microsystems](/source/Sun_Microsystems) and [Oracle Corporation](/source/Oracle_Corporation), [PowerPC](/source/PowerPC)-based computers from Apple, and computers from [Genesi](/source/Genesi)

- ARCS, used in computers from [Silicon Graphics](/source/Silicon_Graphics)

- [Kickstart](/source/Kickstart_(Amiga)), used in the [Amiga](/source/Amiga) line of computers ([POST](/source/Power-on_self-test), hardware init + [Plug and Play](/source/Plug_and_Play) [auto-configuration](/source/Autoconfig) of peripherals, [kernel](/source/Kernel_(operating_system)), etc.)

- [RTAS](/source/Run-Time_Abstraction_Services) (Run-Time Abstraction Services), used in [System i](/source/IBM_System_i) and [System p](/source/System_p) computers from [IBM](/source/IBM)

- The [Common Firmware Environment](/source/Common_Firmware_Environment) (CFE) for [Broadcom](/source/Broadcom) [systems-on-chip](/source/Systems-on-chip) (SoCs)

Updating the firmware of a [Fuji Instax](/source/Instax) camera

### Home and personal-use products

Consumer products like [digital cameras](/source/Digital_camera) and [portable music players](/source/Portable_music_player) support firmware upgrades. In digital cameras, firmware upgrades address bugs in the operation, along with adding new functions to the camera's operation. Some companies use firmware updates to add new playable file formats ([codecs](/source/Codecs)). Other features that may change with firmware updates include the user interface or even the battery life.

### Automobiles

Since 1996, most [automobiles](/source/Automobile) have employed an on-board computer and various sensors to detect mechanical problems. As of 2010[\[update\]](https://en.wikipedia.org/w/index.php?title=Firmware&action=edit), modern vehicles also employ computer-controlled [anti-lock braking systems](/source/Anti-lock_braking_system) (ABS) and computer-operated [transmission control units](/source/Transmission_control_unit) (TCUs). The driver can also get in-dash information while driving in this manner, such as real-time fuel economy and tire pressure readings. Local dealers can update most vehicle firmware.

### Other examples

Other firmware applications include:

- In home and personal-use products: - Timing and control systems for [washing machines](/source/Washing_machine) - Controlling sound and video attributes, as well as the channel list, in modern [televisions](/source/Television)

- In [routers](/source/Network_router), [switches](/source/Network_switch), and [firewalls](/source/Firewall_(computing)): - [LibreCMC](/source/LibreCMC) – a 100% [free software](/source/Free_software) router distribution based on the [Linux-libre](/source/Linux-libre) kernel - [IPFire](/source/IPFire) – an [open-source](/source/Open-source_software) firewall/router distribution based on the [Linux kernel](/source/Linux_kernel) - [fli4l](/source/Fli4l) – an open-source firewall/router distribution based on the Linux kernel - [OpenWrt](/source/OpenWrt) – an open-source firewall/router distribution based on the Linux kernel - [m0n0wall](/source/M0n0wall) – an embedded firewall distribution of [FreeBSD](/source/FreeBSD) - [Proprietary firmware](/source/Proprietary_firmware)

- In [NAS](/source/Network-attached_storage) systems: - [NAS4Free](/source/NAS4Free) – an open-source NAS operating system based on FreeBSD - [Openfiler](/source/Openfiler) – an open-source NAS operating system based on the Linux kernel - [Proprietary firmware](/source/Proprietary_firmware)

- [CPLD](/source/CPLD) or [FPGA](/source/FPGA) code may be referred to as firmware

## Flashing

*Flashing*[5] is a process that involves the overwriting of existing firmware or data, contained in [EEPROM](/source/EEPROM) or [flash memory](/source/Flash_memory) module present in an electronic device, with new data.[5] This can be done to upgrade a device[6] or to change the provider of a service associated with the function of the device, such as changing from one mobile phone service provider to another or installing a new operating system. If firmware is upgradable, it is often done via a program from the provider, and will often allow the old firmware to be saved before upgrading so it can be reverted to if the process fails, or if the newer version performs worse. Free software replacements for vendor flashing tools have been developed, such as [Flashrom](/source/Flashrom_(utility)).

## Firmware hacking

Main article: [Custom firmware](/source/Custom_firmware)

Sometimes, third parties develop an unofficial new or modified ("aftermarket") version of firmware to provide new features or to unlock hidden functionality; this is referred to as [custom firmware](/source/Custom_firmware). An example is [Rockbox](/source/Rockbox) as a firmware replacement for [portable media players](/source/Portable_media_players). There are many [homebrew](/source/Homebrew_(video_games)) projects for various devices, which often unlock general-purpose computing functionality in previously limited devices (e.g., running [Doom](/source/Doom_(1993_video_game)) on [iPods](/source/IPod)).

Firmware hacks usually take advantage of the firmware update facility on many devices to install or run themselves. Some, however, must resort to [exploits](/source/Exploit_(computer_security)) to run, because the manufacturer has attempted to lock the hardware to stop it from running [unlicensed code](/source/Unsigned_code).

Most firmware hacks are [free software](/source/Free_software).

### HDD firmware hacks

The Moscow-based [Kaspersky Lab](/source/Kaspersky_Lab) discovered that a group of developers it refers to as the [Equation Group](/source/Equation_Group) has developed [hard disk drive](/source/Hard_disk_drive) firmware modifications for various drive models, containing a [trojan horse](/source/Trojan_horse_(computing)) that allows data to be stored on the drive in locations that will not be erased even if the drive is formatted or wiped.[7] Although the Kaspersky Lab report did not explicitly claim that this group is part of the United States [National Security Agency](/source/National_Security_Agency) (NSA), evidence obtained from the code of various Equation Group software suggests that they are part of the NSA.[8][9]

Researchers from the Kaspersky Lab categorized the undertakings by Equation Group as the most advanced hacking operation ever uncovered, also documenting around 500 infections caused by the Equation Group in at least 42 countries.

## Security risks

[Mark Shuttleworth](/source/Mark_Shuttleworth), the founder of the company [Canonical](/source/Canonical_(company)), which created the [Ubuntu Linux](/source/Ubuntu_Linux) distribution, has described [proprietary](/source/Proprietary_software) firmware as a security risk, saying that "firmware on your device is the [NSA](/source/NSA)'s best friend" and calling firmware "a trojan horse of monumental proportions". He has asserted that low-quality, [closed source](/source/Closed_source) firmware is a major threat to system security:[10] "Your biggest mistake is to assume that the NSA is the only institution abusing this position of trust – in fact, it's reasonable to assume that all firmware is a cesspool of insecurity, courtesy of incompetence of the highest degree from manufacturers, and competence of the highest degree from a very wide range of such agencies". As a potential solution to this problem, he has called for declarative firmware, which would describe "hardware linkage and dependencies" and "should not include [executable code](/source/Executable_code)".[11] Firmware should be [open-source](/source/Open-source_software) so that the code can be checked and verified.

Custom firmware hacks have also focused on injecting [malware](/source/Malware) into devices such as smartphones or [USB devices](/source/USB_device). One such smartphone injection was demonstrated on the [Symbian OS](/source/Symbian_OS#Malware) at [MalCon](/source/MalCon),[12][13] a [hacker convention](/source/Hacker_convention). A USB device firmware hack called [BadUSB](/source/BadUSB) was presented at the [Black Hat USA 2014](/source/Black_Hat_Briefings) conference,[14] demonstrating how a USB flash drive microcontroller can be reprogrammed to spoof various other device types to take control of a computer, exfiltrate data, or spy on the user.[15][16] Other security researchers have worked further on how to exploit the principles behind BadUSB,[17] releasing at the same time the source code of hacking tools that can be used to modify the behavior of different USB devices.[18]

## See also

- [Electronics portal](https://en.wikipedia.org/wiki/Portal:Electronics)

- [Bootloader](/source/Bootloader)

- [Computer hardware](/source/Computer_hardware)

- [Coreboot](/source/Coreboot)

- [Custom firmware](/source/Custom_firmware)

- [Microcode](/source/Microcode)

- [Proprietary device driver](/source/Proprietary_device_driver)

- [Real-time operating system](/source/Real-time_operating_system)

- [ROM image](/source/ROM_image)

## References

1. **[^](#cite_ref-1)** ["W25X20CL Datasheet"](https://www.winbond.com/hq/support/documentation/?__locale=en&line=/product/code-storage-flash-memory/index.html&family=/product/code-storage-flash-memory/serial-nor-flash/index.html&pno=W25X20CL&category=/.categories/resources/datasheet/). [Winbond](/source/Winbond). Retrieved 2024-08-30.

1. **[^](#cite_ref-2)** ["What is firmware?"](http://incepator.pinzaru.ro/software/what-is-firmware/). 23 January 2013.

1. **[^](#cite_ref-Opler_3-0)** Opler, Ascher (January 1967). ["Fourth-Generation Software"](https://archive.org/details/TNM_4th_generation_software_hardware_-_Datamation_20171010_0125). *Datamation*. **13** (1): 22–24.

1. **[^](#cite_ref-4)** Mielewczik, Michael (2000). "Firmware-Update. Mehr Speed und Sicherheit". *PC Praxis* (in German). 1/2000: 68.

1. ^ [***a***](#cite_ref-techfaq_5-0) [***b***](#cite_ref-techfaq_5-1) ["Flashing Firmware"](http://www.tech-faq.com/flashing-firmware.html). Tech-Faq.com. [Archived](https://web.archive.org/web/20110927010726/http://www.tech-faq.com/flashing-firmware.html) from the original on September 27, 2011. Retrieved July 8, 2011.

1. **[^](#cite_ref-6)** ["HTC Developer Center"](https://web.archive.org/web/20110426201145/http://developer.htc.com/adp.html). [HTC](/source/HTC). Archived from [the original](http://developer.htc.com/adp.html) on April 26, 2011. Retrieved July 8, 2011.

1. **[^](#cite_ref-7)** ["Equation Group: The Crown Creator of Cyber-Espionage"](http://www.kaspersky.com/about/news/virus/2015/Equation-Group-The-Crown-Creator-of-Cyber-Espionage). [Kaspersky Lab](/source/Kaspersky_Lab). February 16, 2015. [Archived](https://web.archive.org/web/20151202101934/http://www.kaspersky.com/about/news/virus/2015/equation-group-the-crown-creator-of-cyber-espionage) from the original on December 2, 2015.

1. **[^](#cite_ref-8)** Dan Goodin (February 2015). ["How "omnipotent" hackers tied to NSA hid for 14 years—and were found at last"](https://arstechnica.com/security/2015/02/how-omnipotent-hackers-tied-to-the-nsa-hid-for-14-years-and-were-found-at-last/). *[Ars Technica](/source/Ars_Technica)*. [Archived](https://web.archive.org/web/20160424062759/http://arstechnica.com/security/2015/02/how-omnipotent-hackers-tied-to-the-nsa-hid-for-14-years-and-were-found-at-last/) from the original on 2016-04-24.

1. **[^](#cite_ref-9)** ["Breaking: Kaspersky Exposes NSA's Worldwide, Backdoor Hacking of Virtually All Hard-Drive Firmware"](https://www.dailykos.com/story/2015/02/17/1364910/-Breaking-Kaspersky-Exposes-NSA-s-Worldwide-Backdoor-Hacking-of-Virtually-All-Hard-Drive-Firmware). [Daily Kos](/source/Daily_Kos). February 17, 2015. [Archived](https://web.archive.org/web/20150225044646/http://www.dailykos.com/story/2015/02/17/1364910/-Breaking-Kaspersky-Exposes-NSA-s-Worldwide-Backdoor-Hacking-of-Virtually-All-Hard-Drive-Firmware) from the original on February 25, 2015.

1. **[^](#cite_ref-linux-mag-162_10-0)** "Shuttleworth Calls for Declarative Firmware". *Linux Magazine*. No. 162. May 2014. p. 9.

1. **[^](#cite_ref-11)** [Shuttleworth, Mark](/source/Mark_Shuttleworth) (March 17, 2014). ["ACPI, firmware and your security"](http://www.markshuttleworth.com/archives/1332). [Archived](https://web.archive.org/web/20150315054919/http://markshuttleworth.com/archives/1332) from the original on March 15, 2015.

1. **[^](#cite_ref-12)** ["MalCon 2010 Technical Briefings"](https://web.archive.org/web/20110704040605/http://malcon.org/web/techbrief/malcon-2010-technical-briefings/). *Malcon.org*. Archived from [the original](http://malcon.org/web/techbrief/malcon-2010-technical-briefings/) on 2011-07-04.

1. **[^](#cite_ref-13)** ["Hacker plants back door in Symbian firmware"](https://web.archive.org/web/20130521142131/http://www.h-online.com/security/news/item/Hacker-plants-back-door-in-Symbian-firmware-1149926.html). *H-online.com*. 2010-12-08. Archived from [the original](http://www.h-online.com/security/news/item/Hacker-plants-back-door-in-Symbian-firmware-1149926.html) on 21 May 2013. Retrieved 2013-06-14.

1. **[^](#cite_ref-14)** ["Why the Security of USB Is Fundamentally Broken"](https://www.wired.com/2014/07/usb-security/). *Wired.com*. 2014-07-31. [Archived](https://web.archive.org/web/20140803200841/http://www.wired.com/2014/07/usb-security/) from the original on 2014-08-03. Retrieved 2014-08-04.

1. **[^](#cite_ref-15)** ["BadUSB - On Accessories that Turn Evil"](https://www.blackhat.com/us-14/briefings.html#badusb-on-accessories-that-turn-evil). *BlackHat.com*. [Archived](https://web.archive.org/web/20140808053344/https://www.blackhat.com/us-14/briefings.html#badusb-on-accessories-that-turn-evil) from the original on 2014-08-08. Retrieved 2014-08-06.

1. **[^](#cite_ref-16)** Karsten Nohl; Sascha Krißler; Jakob Lell (2014-08-07). ["BadUSB – On accessories that turn evil"](https://srlabs.de/wp-content/uploads/2014/07/SRLabs-BadUSB-BlackHat-v1.pdf) (PDF). *srlabs.de*. [Archived](https://web.archive.org/web/20161019034729/https://srlabs.de/wp-content/uploads/2014/07/SRLabs-BadUSB-BlackHat-v1.pdf) (PDF) from the original on 2016-10-19. Retrieved 2014-08-23.

1. **[^](#cite_ref-17)** ["BadUSB Malware Released — Infect millions of USB Drives"](https://web.archive.org/web/20141006121457/http://hackingpost.com/badusb-malware-infect-millions-of-usb/). *The Hacking Post*. Archived from the original on 6 October 2014. Retrieved 7 October 2014.

1. **[^](#cite_ref-18)** Greenberg, Andy. ["The Unpatchable Malware That Infects USBs Is Now on the Loose"](https://www.wired.com/2014/10/code-published-for-unfixable-usb-attack/). *WIRED*. [Archived](https://web.archive.org/web/20141007092141/http://www.wired.com/2014/10/code-published-for-unfixable-usb-attack/) from the original on 7 October 2014. Retrieved 7 October 2014.

v t e Firmware and booting Processes Windows 9x NT Linux Android Booting firmware Types Proprietary firmware Open-source firmware Custom firmware Interfaces UEFI BIOS Video BIOS Open Firmware ACPI MultiProcessor Specification APM Legacy Plug and Play AlphaBIOS SRM SFI Implementations SeaBIOS Award BIOS American Megatrends AMIBIOS AMI Aptio InsydeH2O Phoenix SecureCore UEFI TianoCore EDK II OpenBIOS Coreboot Libreboot LinuxBoot Kickstart Run-Time Abstraction Services Hybrid firmware bootloader Common Firmware Environment Das U-Boot Bootloaders Bootloader unlocking Comparison of bootloaders Implementations Acronis OS Selector Barebox BootManager BootX (Apple) BootX (Linux) GNU GRUB iBoot LILO Limine loadlin MILO NTLDR OpeniBoot Plop Boot Manager RedBoot rEFInd rEFIt SYSLINUX systemd-boot Windows Boot Manager xOSL Yaboot Partition layouts GUID Partition Table Master boot record Apple Partition Map Partitions EFI system partition BIOS boot partition /boot/ Utilities Software flashrom fwupd UEFITool Odin Heimdall Hardware Bus Pirate Raspberry Pi ft2232 Network boot Preboot Execution Environment gPXE iPXE NetBoot Remote Initial Program Load Wake-on-LAN Wake-on-ring ROM variants ROM PROM EPROM EEPROM Related Boot ROM ROM hacking ROM image Execute in place Devicetree Fastboot Instant-on Power-on self-test EDL mode

v t e Embedded systems General terms ASIC Board support package Bootloader Consumer electronics Cross compiler Embedded database Embedded hypervisor Embedded OS Embedded software FPGA IoT Memory footprint Microcontroller Single-board computer Raspberry Pi SoC Firmware, controls Firmware Custom firmware Proprietary firmware Closed platform Crippleware Defective by Design Hacking of consumer electronics Homebrew (video games) iOS jailbreaking PlayStation 3 Jailbreak Rooting (Android) UEFI Vendor lock-in Boot loaders U-Boot Barebox Software libraries uClibc dietlibc Embedded GLIBC lwIP musl Programming tools Almquist shell BitBake Buildroot BusyBox OpenEmbedded Stand-alone shell Toybox Yocto Project Operating systems Linux on embedded systems Linux for mobile devices Light-weight Linux distribution Real-time operating system Windows IoT Win CE Programming languages Ada Assembly language CAPL Embedded C Embedded C++ Embedded Java MISRA C MicroPython Lightweight browsers List of open-source hardware Open-source robotics

Authority control databases International GND FAST National United States Japan Israel Other Yale LUX

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Adapted from the Wikipedia article [Firmware](https://en.wikipedia.org/wiki/Firmware) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Firmware?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.