You can think of it as a combination of hardware and software. Firmware is computer programming instructions stored on a fixed hardware device such as a ROM chip. It is basically software that cannot be changed, except by changing the hardware. Firmware is often responsible for the behavior of a system when it is first switched on. A typical example would be a ROM program in a microcomputer that loads the full OS from disk or from a network and then passes control to it. In many electronic instruments we use the entire operating system is in firmware. This means that any updates require swapping out chips.