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What Is The BIOS?

In this post I go over what the BIOS is, along with a brief history of the BIOS.

What is the BIOS?

Rather watch than read?

Almost everyone who has turned on a PC and watched the screen has seen the word BIOS, but what exactly is it? It’s actually very simple, but is also perhaps the important part of the booting process.

What is a BIOS?

The BIOS (Basic Input Output System) is the very first piece of software that runs when you boot the computer up. Its job is to ensure that all of the hardware is started up and working properly before eventually initializing the loading process for your computer’s operating system. The BIOS is stored on a ROM (Read-Only Memory) chip on the motherboard.

Not sure about motherboards? I have a blog post about motherboards right here.

The BIOS has settings that are stored on what is called the CMOS (Complementary metal-oxide semiconductor). That’s an intimidating term, but for now just know that it stores BIOS settings such as the date and time, boot settings, and depending on the BIOS your computer has, there can be many more complex settings. The CMOS requires constant electricity in order to store these settings, so you will almost certainly see a small battery somewhere on the motherboard similar to what you’d see in a watch. If you pull this battery out, you are effectively resetting all of the BIOS’ settings. This is of course because without the power from the battery, the CMOS is unable to hold the BIOS information. Often times, this is the acceptable way to reset the BIOS settings.

A Brief History of the BIOS

The original BIOS was developed for CP/M (Control Program for Microcomputer), by Gary Kildall in 1975. At the time, it was proprietary, but later DOS operating systems had early versions of BIOS’ as well. Eventually Glenn Ewing and Gary Kildall worked together to separate the BIOS from the CP/M, making it possible to develop BIOS’ for all sorts of systems.

More on the BIOS

When you load up a BIOS screen to adjust settings and such, it can often look somewhat cryptic. This is where the UEFI (Unified Extensible Firmware Interface) came into play. UEFI is expected to fully replace BIOS eventually, and nowadays it’s pretty common to see this in place of the classic BIOS. UEFI’s often have a much more pleasant graphical user interface or GUI for short, that is more intuitive and offers more features than a classic BIOS.

Can the BIOS Be Upgraded?

Updating a BIOS or UEFI in a computer is not an amateur task. It typically requires flashing the ROM, which is the process of wiping out the Read-Only Memory chip and replacing it with the new BIOS or UEFI. If anything goes wrong during the flashing process the chip could be rendered useless. Updating the BIOS can lead to increased functionality of your computer, but if you are untrained, you will want a technician to do this for you.

A Brief history of the BIOS