In a CD recorder, firmware is the programming instructions contained on a ROM chip within the CD recorder which tell the recorder how to respond to commands issued by software. Some firmware is flash-upgradeable, meaning that you can upgrade the firmware by running a piece of software on the computer attached to the recorder. Other firmware is coded into non-rewriteable chip, so the entire chip must be changed in order to upgrade the firmware.
Dude just have a scan to this link..for a more clear picture
*en.wikipedia.org/wiki/Firmware
This will surelly help you