Prior to 1990 or so BIOSes were installed on ROM chips that could not be changed. As its intricacy and requirement for updates grew, BIOS firmware was subsequently loaded on EEPROM or flash memory devices. The first flash chips being added to the ISA bus. Making its journey in 1998, the BIOS flash shifted to the LPC bus, a functional substitute for ISA, following a new upgraded execution considered to be as "firmware hub" (FWH). In 2006, the first systems giving back up to a Serial Peripheral Interface (SPI) being available, and the BIOS flash darted again.



EEPROM chips are suitable because they can be modified and upgraded by the user with much comfort. The hardware manufacturers sometimes issue BIOS updates to advance their products, develop competence and delete bugs. However it is the fact that there is the risk in the implementation of BIOS update in imperfect way can make the computer or device unusable. If someone wants to rescue the system from BIOS corruption, some new motherboards are loaded with backup BIOS which can be referred to Dual BIOS boards.

At the same time Gigabyte even provides a motherboard with quad BIOS. There are most BIOSes which are equipped with boot block which is a part of the ROM that runs first. This code will make verification that the rest of the BIOS is kept protected via checksum, hash etc. prior to hand over the control to it. In case the boot block surfaces that the main BIOS is not good. It is corrupted. Then it will typically start a recovery process by booting to a removable media like floppy, CD or USB memory so that the user can make an attempt to flash again. Owing to the restriction on the number of times that there is the higher possibility of the flashing of the flash memory. A flash based BIOS is prone to flash burn viruses that again and again write to the flash resulting the corruption of the chip.