Firmware is optical drives Bios . Like Motherboard Bios it can be flashed/upgraded . Bios is both a Hardware ( the EEPROM flash memory on the motherboard or device ) and Software ( the info/data/program stored in it to operate the Motherboard or device ) part . Of course most of the time when we talk about Bios/Firmware , we are speaking about his Software side because most of the time we want to upgrade the program stored in the EEPROM flash memory .
Bios is basically a link between Hardware and Software ( like O.S but at a much lower/basic level ) , without Bios a Motherboard cannot achieve Boot and some basic tasks . In modern motherboards there is a little part unflashable in the bios called "BootBlock" allowing floppy disk boot after a bad flash and able to search available Bios on the floppy ( for further information you can go there for example : http://www.wimsbios.com/index.htm?/HTML1/faq.html
This is the case for example with my Epox 8KTA3 chipset VIA KT133A ( it contains Bootblock ) . Without Bios a device like CD/RW ( i.e after a bad Firmware flash ) cannot be used by Software like burning Software ( Dimitri has created an utility allowing to flash a drive after a bad flash : http://www.digitri.tk/