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Understanding BIOS: The Basic Input/Output System

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BIOS, or Basic Input/Output System, is a fundamental component of a computer. It is a type of firmware used during the booting process (startup) of any computer. It’s the first software that runs when you turn on your computer, and it’s responsible for initializing and testing the system hardware components, and loading the operating system into the computer’s memory. You can think of it as the bridge that connects the hardware and software components of a computer.

The History of BIOS

The term BIOS was first coined in 1975 by American computer scientist Gary Kildall. It was incorporated into IBM’s first personal computer in 1981 and, in the years to come, gained popularity within other PCs, becoming an integral part of computers for some time. Intel announced a plan in 2017 to retire support for legacy BIOS systems by 2020, replacing them with UEFI (Unified Extensible Firmware Interface). You can read more about the history of BIOS here.

The Uses of BIOS

The main use of BIOS is to act as a middleman between operating systems and the hardware they run on. BIOS is theoretically always the intermediary between the microprocessor and I/O device control information and data flow. Although, in some cases, BIOS can arrange for data to flow directly to memory from devices, such as video cards, that require faster data flow to be effective.

How Does BIOS Work?

BIOS comes included with computers as firmware on a chip on the motherboard. When users turn on their computer, the microprocessor passes control to the BIOS program, which is always located at the same place on EPROM (Erasable Programmable Read-Only Memory) chip. When BIOS boots up a computer, it first determines whether all of the necessary attachments are in place and operational. Any piece of hardware containing files the computer needs to start is called a boot device. After testing and ensuring boot devices are functioning, BIOS loads the operating system — or key parts of it — into the computer’s random access memory (RAM) from a hard disk or diskette drive (the boot device).

The Four Functions of BIOS

BIOS identifies, configures, tests, and connects computer hardware to the operating system immediately after a computer is turned on. The combination of these steps is called the boot process. This tests the hardware of the computer before loading the operating system. This locates the software and drivers that interface with the operating system once running. Complementary metal-oxide-semiconductor (CMOS) setup is a configuration program that enables users to alter hardware and system settings. CMOS is the name of BIOS’ non-volatile memory.

Accessing BIOS

With BIOS, the operating system and its applications are freed from having to understand exact details, such as computer hardware addresses, about the attached I/O devices. When device details change, only the BIOS program needs to be changed. Sometimes, this change can be made during system setup. Users can access BIOS and configure it through BIOS Setup Utility. Accessing BIOS Setup Utility varies somewhat depending on the computer being used. When the computer turns back on, look for a message that says “entering setup” or something similar. Accompanying that message will be a key that the user should press to enter system configuration. Some keys often usedas prompts are Del, Tab, Esc, and any of the function keys (F1-F12). Upon seeing the prompt, quickly press the key specified. Once in BIOS Setup Utility, users can change hardware settings, manage memory settings, change the boot order or boot device, and reset the BIOS password, among other configuration tasks.

Here is our guide to check and update BIOS version

BIOS Security

BIOS security is a somewhat overlooked component of cybersecurity; however, it should still be managed to prevent hackers from executing malicious code on the operating system. Security group Cylance, in 2017, showed how modern BIOS security flaws could enable ransomware programs inside a motherboard’s UEFI and exploit other PC BIOS vulnerabilities. Another unique exploit involving the manipulation of BIOS was Plundervolt. Plundervolt could be used to mess with a computer’s power supply at the time data was being written to memory, causing errors that lead to security gaps. Intel released a BIOS patch to defend against it.

BIOS Manufacturers

BIOS, in its beginnings, was originally owned by IBM. However, some companies, such as Phoenix Technologies, have reverse-engineered IBM’s original version to create their own. Phoenix, in doing this, allowed other companies to create clones of the IBM PC and, more importantly, create non-IBM computers that work with BIOS. One company that did this was Compaq. Today, many manufacturers produce motherboards with BIOS chips in them. Driver updates may improve computer performance or patch recent BIOS-level security vulnerabilities. Each manufacturer has a unique way of updating these drivers.

In conclusion, BIOS is a fundamental part of any computer system. It is the bridge between the hardware and the operating system, ensuring that your computer boots up correctly and runs smoothly. Understanding how it works and its importance can help you troubleshoot issues and optimize your computer’s performance.

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Gyula Virag
Gyula Virag

Gyula is a developer and a passionate geek father with a deep love of online marketing and technology. He always seeks challenging adventures and opportunities to create something permanent in the digital world.

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