BIOS – Basic input/output System

What is BIOS?

Basic input/output system is a non volatile firmware that performs hardware initialization during when you boot a computer. BIOS initializes and test all the hardware that needs to be functioned together in a computer and after the check up BIOS loads the device drivers and operating system to the RAM, which then boot the computer.

Programming language used for BIOS

While in theory one can write BIOS in any programming language, the modern reality is most BIOS is written using AssemblyC, or a combination of the two. BIOS must be written in a language that can compile to machine code that is understood by the physical hardware-machine.

Main functions of BIOS

  1. A power-on self-test (POST) test the computer hardware and make sure no errors exist before loading the operating system.
  2. Locate the operating system
  3. Loading drivers that give the computer basic operational control over hardware.
  4. Allows configuring hardware settings including system settings such as computer passwords, time, and date.

How BIOS works

The first thing the BIOS do is check the information stored in a tiny (64 bytes) amount of RAM located on a complementary metal oxide semiconductor (CMOS) chip. The CMOS Setup provides detailed information particular to your system and can be altered as your system changes. The BIOS uses this information to modify or supplement its default programming as needed.

After checking the CMOS Setup and loading the interrupt handlers, the BIOS determine whether the video card is operational.

Next, the BIOS checks to see if this is a cold boot or a reboot, then the BIOS verifies RAM.

The BIOS uses CMOS technology to save any changes made to the computer’s settings. With this technology, a small lithium or Ni-Cad battery can supply enough power to keep the data for years.

What is CMOS?

CMOS is short for Complementary Metal-Oxide Semiconductor referred to as a Real-Time Clock (RTC), Non-Volatile RAM (NVRAM) or CMOS RAM. CMOS is an on-board, battery powered semiconductor chip inside computers that stores information. This information ranges from the system time and date to system hardware settings for your computer.

Popular BIOS Manufacturers

The following are some of the more popular BIOS vendors:

  1. Phoenix Technologies
  2. IBM
  3. Dell
  4. Gateway
  6. American Megatrends (AMI)
  7. Insyde Software

Note: Award Software, General Software, and Microid Research were BIOS vendors that were acquired by Phoenix Technologies.

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You may also like to read

Click here to learn about motherboards

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