UK How firmware works
Firmware is software that is built into a hardware device and stored in its non-volatile memory, so it stays in place when power is off. It controls the hardware directly: it sets up the chips, reads buttons and sensors, drives outputs and, on a computer, hands over to the operating system. The name reflects its position between fixed hardware and changeable software.
Early firmware was written into read-only memory at the factory and could not be changed. EPROM and EEPROM allowed it to be rewritten with special equipment, and today almost all firmware lives in flash memory that can be updated in the field. That flexibility is useful, because bugs can be fixed after shipping, but it also makes firmware a target for attackers.
Firmware is everywhere in electronics: in washing machines, cars, cameras, keyboards and every component inside a computer. A single industrial PC can carry a dozen separate firmware images, each with its own version and update process.
Types of firmware in a computer
The firmware most people mean is the UEFI or BIOS that starts the computer. It is only one of several layers, and each can affect how a system behaves on site.
| Firmware | Where it lives | What it does | How it is usually updated |
|---|---|---|---|
| UEFI or BIOS | SPI flash chip on the motherboard | Initialises the hardware and boots the operating system | Board maker’s tool or a UEFI capsule |
| Embedded controller | Small microcontroller on the board | Power sequencing, fans, ignition and wake events | Bundled with the UEFI update |
| Management engine | Inside the chipset or processor | Security and remote management functions | Bundled with the UEFI update or a separate package |
| SSD controller | The drive’s own flash and controller | Wear levelling, error correction and power-loss handling | Drive maker’s tool |
| Network and Wi-Fi | Network controller or module | Link control and offload features | Driver package or vendor tool |
| Peripherals and I/O | Microcontrollers on cards, cameras and modules | Run the device’s own logic | Vendor tool, often over USB or serial |
On Arm and embedded boards, the boot firmware, Linux kernel and drivers are delivered together as a board support package that brings up the operating system. Changing the board, even to a new revision, can mean a new package.
Firmware vs software vs hardware
The three are layers of the same device. Hardware is the physical circuitry. Firmware is the fixed program that makes that particular hardware work. Software is everything that runs on top: the operating system and applications, which can be installed, removed and moved to another machine.
The line is not always sharp. A computer’s UEFI is firmware, but it is large enough to include a network stack and a graphical menu. A router or camera may run a full Linux system that is still called firmware, because it is supplied as one image tied to that device.
How firmware updates work
A firmware update replaces the image in the device’s flash memory with a new version. On PCs this is often delivered as a UEFI capsule through Windows Update, or through the Linux fwupd service, and the firmware applies it on the next restart. Other devices use a vendor utility, a USB stick or a web interface.
Updates fix bugs, close security holes, add support for new processors, memory or drives, and sometimes change default behaviour. Because a failed update can stop a device starting, good practice is to:
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Read the release notes. Update to fix a known problem or a security flaw, not simply because a newer version exists.
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Keep power stable. Use mains or a charged battery, never a supply that might drop, and do not interrupt the process.
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Record settings first. Some updates reset UEFI options such as boot order or power-on behaviour.
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Test before rolling out. Try the update on one system with the real operating system image before applying it to a fleet.
Firmware on industrial systems
On industrial and embedded systems, firmware is part of the configuration that has to stay the same across a fleet and for the life of a project. A change of firmware version can alter boot timing, power behaviour or device support, so it is tracked like any other part of the bill of materials.
Security guidance treats firmware as its own layer. NIST SP 800-193 sets out three goals for platform firmware: protect it from unauthorised change, detect corruption, and recover to a known good state. On computers in remote cabinets or vehicles, out-of-band management for remote recovery lets firmware be updated or a system recovered without a site visit.
Quick answers on firmware
Firmware: common questions
Is firmware software?
Yes, a specific kind. Firmware is software built for one piece of hardware and stored on it. Ordinary software runs on top of an operating system and can move between machines; firmware usually cannot.
What is a firmware update?
A new version of the code stored on a device. It is written to the device’s flash memory, a process called flashing, and typically fixes bugs, closes security holes or adds hardware support.
Does a firmware update erase my data?
Normally not. Firmware sits in its own memory, separate from files on the drive. Some updates do reset settings to default, so note custom settings before updating, and back up the data anyway.
Can I undo a firmware update?
Sometimes. Many boards allow a rollback, but some updates block it on purpose so that a fixed security flaw cannot be reintroduced. Check the release notes before updating.
What happens if a firmware update fails?
The device may not start. A power cut mid-update can leave corrupt firmware. Boards with dual or recovery flash can restore themselves; others need reprogramming, so update on a stable supply.
We record and fix the firmware versions in every industrial PC we supply as standard, set the UEFI options each project needs and validate firmware updates before they reach a fleet.