Firmware is programming that is inserted into electrically erasable programmable read-only memory (EEPROM), thus becoming a permanent part of an instrument. It provides the complete instrument's functionality.
The firmware has been tested under the control of the Software/Firmware QA, according the rules of software/firmware development. When ready, it is distributed and, using a special user interface, installed in the EEPROM by the user. Updating the firmware might be necessary due to new released firmware revisions (new features, instrument improvements) or after replacing the electronic board (repair) that houses the EEPROM.