Firmware

thumb|right|Firmware is commonly stored in an EEPROM or Flash memory, which makes use of an I/O protocol such as SPI.

In computer architecture, microcode is a layer of low-level control data or instructions used to implement a processor's instruction set architecture or internal control sequences. It consists of hardware-level operations that carry out higher-level machine code instructions or direct internal sequencing in many digital components. In many modern Intel and AMD general-purpose processors, common instructions are decoded directly into internal micro-operations, while microcode is used mainly for more complex instructions, special cases, and processor updates.

coreboot (formerly LinuxBIOS) is an open‑source project that provides lightweight firmware to initialize hardware and then load an operating system. It is designed to replace proprietary firmware (traditional BIOS or UEFI implementations) by performing the minimal tasks required to start a modern 32-bit or 64-bit operating system.

Libreboot (briefly known as GNU Libreboot) is a free and open-source software project based on coreboot, aimed at replacing some of the proprietary BIOS or UEFI firmware on supported x86-64 and AArch64 computers. Libreboot performs the basic machine setup such as CPU initialization or memory controller initialization necessary to load and run a 32-bit or 64-bit operating system, such as Linux or BSD. It was tested on FreeBSD, NetBSD, and OpenBSD.

set of software routines that emulate platform-specific details, giving programs direct access to hardware resources in a device-independent, high performance manner

Preboot Execution Environment

closed-source device driver published only as binary code

multi-platform free software boot loader

data dump from a ROM chip

technical standard

OpenBIOS is a project aiming to provide free and open source implementations of Open Firmware. It is also the name of such an implementation.

method of executing programs directly from long-term storage

firmware and software that runs on all modern Intel CPUs at a higher level than user-facing operating system

software needed to operate motherboards

Amiga firmware

trusted execution environment subsystem

LinuxBoot is a free software project aimed at replacing most of the Driver Execution Environment (DXE) modules in Unified Extensible Firmware Interface (UEFI) firmware with the Linux kernel. LinuxBoot must run on top of hardware initialisation software in order to start. This can be the Pre-EFI Initialization (PEI) part of UEFI, coreboot, or U-Boot. It can boot Linux through the kexec syscall, but is also able to boot Windows with a different method.

Barebox is a primary boot loader used in embedded devices. It is free software under the GPL-2.0-only license. It is available for a number of different computer architectures, including ARM, x86, MIPS and RISC-V.

open source firmware for 3D printers