What is BIOS?
The BIOS (for BASIC Input/Output System) is a whole of routines (programmmes) which allows the operating system to manage the various elements of the mother board. These instructions are stored in a EEPROM (for Electrically Eraseable Programmable Read Only Memory). The process of update is thus a little more complex and riskier than that of a normal software. In the event of a bad handling, the contents of the EEPROM of the BIOS can be deteriorated, which can prevent the PC from correctly functioning, to even ignite.
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Tutorials - Bios