This may require ROM integrated circuits to be physically replaced, or flash memory to be reprogrammed through a special procedure.
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.
The BIOS may be "manually" updated by a user, using a small utility program.
In contrast, firmware in storage devices (harddisks, DVD drives, flash storage) rarely gets updated, even when flash (rather than ROM) storage is used for the firmware; there are no standardized mechanisms for detecting or updating firmware versions.
Firmware such as the program of an embedded system may be the only program that will run on the system and provide all of its functions.
Before the inclusion of integrated circuits, other firmware devices included a discrete semiconductor diode matrix.
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 processor machine instructions for BIOS, bootstrap loaders, or the control systems for simple electronic devices such as a microwave oven, remote control, or computer peripheral.
Right click the Windows logo (lower left corner of your screen).