| Prior to 1990 or so BIOSes were installed on ROM | | | | BIOS corruption, some new motherboards are |
| chips that could not be changed. As its intricacy | | | | loaded with backup BIOS which can be referred |
| and requirement for updates grew, BIOS | | | | to Dual BIOS boards. |
| firmware was subsequently loaded on EEPROM or | | | | At the same time Gigabyte even provides a |
| flash memory devices. The first flash chips being | | | | motherboard with quad BIOS. There are most |
| added to the ISA bus. Making its journey in 1998, | | | | BIOSes which are equipped with boot block which |
| the BIOS flash shifted to the LPC bus, a functional | | | | is a part of the ROM that runs first. This code will |
| substitute for ISA, following a new upgraded | | | | make verification that the rest of the BIOS is |
| execution considered to be as "firmware hub" | | | | kept protected via checksum, hash etc. prior to |
| (FWH). In 2006, the first systems giving back up | | | | hand over the control to it. In case the boot block |
| to a Serial Peripheral Interface (SPI) being | | | | surfaces that the main BIOS is not good. It is |
| available, and the BIOS flash darted again. | | | | corrupted. Then it will typically start a recovery |
| EEPROM chips are suitable because they can be | | | | process by booting to a removable media like |
| modified and upgraded by the user with much | | | | floppy, CD or USB memory so that the user can |
| comfort. The hardware manufacturers sometimes | | | | make an attempt to flash again. Owing to the |
| issue BIOS updates to advance their products, | | | | restriction on the number of times that there is |
| develop competence and delete bugs. However it | | | | the higher possibility of the flashing of the flash |
| is the fact that there is the risk in the | | | | memory. A flash based BIOS is prone to flash |
| implementation of BIOS update in imperfect way | | | | burn viruses that again and again write to the |
| can make the computer or device unusable. If | | | | flash resulting the corruption of the chip. |
| someone wants to rescue the system from | | | | |