What is BIOS and How Does it Work?

BIOS is short for Basic Input Output System. It is essentially the most important part of a computer system. Without BIOS, the computer cannot boot up or even start the OS. BIOS has been there since the era of primitive computers and DOS.

The BIOS is a firmware program stored in an erasable programmable read only memory chip (EPROM) chip. When the Computer is turned on, the microprocessor on-board passes the control to the BIOS, which checks the system from its location on the EPROM chip.


After the BIOS boots up, it performs a predefined set of tasks and checks whether all the hardware components are properly connected and then, boots up the OS in a boot device (e.g. Hard disk, CD or DVD).

How exactly the BIOS helps?

  • A Power on Self Test (POST) is carried out by the BIOS after booting up. It checks all the configured hardware for issues. After making sure there are no issues, it passes the control to the Bootstrap loader.
  • The Bootstrap loader then locates a capable operating system. When found, it then passes the control to it.
  • It then activates the other BIOS chips on the different cards. For example, newer graphics cards come pre-installed with their own firmware updates. It also loads the different low level drivers that give the basic control over the system hardware.
  • CMOS Setup- It allows basic configuration program so that basic hardware and system settings can be changed from the OS such as passwords, date and time, relevance etc.

Besides these, there are a number of other functions which are performed by the BIOS. As the name indicates, it frees the hardware and the OS from having to go through the details of the Input/output devices. Fan speed, memory clocking and power management are some of the things which BIOS can affect.


The BIOS can be regarded as the dark knight. The whole usefulness of the PC depends on the BIOS framework. It is quite easy for technicians to manage and configure system properties through BIOS.

How to Update BIOS?

When new devices in the computer go unrecognized, it becomes necessary to update the BIOS framework. BIOS updates are a bit tacky and should not be done regularly unless absolutely necessary. Before an update, it is essential to check the version installed from the boot menu and then look up at the manufacturer’s website for newer firmware updates.

What to expect from BIOS updates?

  • Compatibility- updated BIOS may help fix problems for newer devices and drivers.
  • Bug Fixes- After all, the BIOS is just code and codes can be altered to vary performance and solve bug issues on the system.
  • Performance- the Updated BIOS may help improve the boot time, among other factors.


I started this tech blog back in 2011 as a place to write down processes I took to fix my client systems and network. Now I write some tips and tricks to help others with the tech issues that one might encounter.

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