Bare machine

In computer science, bare machine (or bare metal) refers to a computer executing instructions directly on logic hardware without an intervening operating system. Modern operating systems evolved through various stages, from elementary to the present day complex, highly sensitive systems incorporating many services. After the development of programmable computers (which did not require physical changes to run different programs) but prior to the development of operating systems, sequential instructions were executed on the computer hardware directly using machine language without any system software layer. This approach is termed the "bare machine" precursor to modern operating systems. Today it is mostly applicable to embedded systems and firmware with time-critical latency requirements, while conventional programs are run by a runtime system overlaid on an operating system.