What is a BIOS and what does BIOS mean?
BIOS - Basic Input Output System
The BIOS is a collection of commands usually stored in a ROM chip, which allows a CPU to communicate with the connected devices in a PC or other digital system.
For more detailed information please see below.
The CPU in a PC needs a way of communicating with the many different hardware devices that are installed, each hardware device has its own special BIOS software which allows for this communication.
The main BIOS in a PC system is stored inside a microchip on the motherboard (mainboard), and is the first piece of software your computer runs when you (boot up) turn it on.
When a PC is first powered-up the BIOS will run the POST (Power On Self Test), which initialises all of the basic hardware devices, including the CPU, RAM, video card, storage devices and DMA controllers. When a system is reset (soft-boot) the BIOS will effectively skip the POST test.
The configuration data used by the BIOS is stored in the CMOS memory which is backed up by a battery. This data includes all of the basic configuration data, including device types and also the date and time.
A Flash BIOS can be updated with new information and many motherboard manufacturers publish updates for their respective BIOS on their websites.