Know BIOS Full Form: Basic Input/Output System

There must have been times when the BIOS automatically turns up when you switch on the desktop/laptop. This could happen when you first buy a computer without Windows or another operating system installed in it. It would also appear when there is a CMOS battery issue. Or it could be that you accidentally pressed the F2 key right after startup. BIOS lets you configure your system in many ways too.

BIOS is a firmware stored in a computer motherboard’s chip during manufacture. And the BIOS full form is basic input/output system. It allows the CPU to load the operating system into the main memory (RAM) and make out which devices (mouse, keyboard, hard drives, etc.) are present and working properly during startup. 

Every motherboard has BIOS in the read only memory (ROM)  or the flash memory chip of the CPU. Irrespective of which version of Windows or Linux OS you may use, BIOS will be present. BIOS knowledge is integral to the job description of an IT Support Engineer, Hardware Engineer, and the like. 

But even as a layperson who uses a computer on a daily basis, or a gamer who wants to overclock the processor, knowing about performing basic settings on BIOS will be of help. 

How BIOS or Basic Input/Output System Works

It is essential to know the fundamental relationship between the hardware component, aka CPU and the software component comprising the operating system, applications, etc.  The main function of BIOS is to make the hardware component interact with the software component. 

It’s like this. You turn on the CPU. It has to provide instructions to run the operating system. Here is where the BIOS comes in. 

Explaining BIOS Functions Step-by-Step

Power-on

After turning on your computer, the power supply sends electricity to the motherboard, providing power to the BIOS chip. 

The BIOS is a small program. It is stored on a ROM (Read-Only Memory) chip that retains its contents even when the computer is powered off. When the power is supplied, the BIOS gets activated.

Power-on self-test (POST)

The first task of the BIOS is to perform a Power-on Self-Test (POST). During POST, the BIOS checks the hardware components, including the processor, memory (RAM), graphics card, hard drives, and other peripherals. The goal is to ensure that all the essential hardware is present and functioning correctly.

Booting Process

After the POST is completed and the hardware is verified, the BIOS initiates the booting process. 

It looks for the boot device where the operating system is located. Initially, the BIOS searches for the boot sector on the primary storage device, typically the hard drive. If found, it loads the boot loader, which further starts the operating system.

Basic System Configuration and Settings

The BIOS also provides a user interface (often accessed by pressing Del, F2, or Esc during startup) to access and modify system settings. 

These settings include options related to the boot order, date and time, CPU and memory configurations, and various other parameters. Users can customise these settings according to their requirements.

Interface Between Hardware and Operating System

Once the operating system is loaded, the BIOS hands over control to the operating system, acting as an interface between the hardware and the software. 

It provides essential services to the operating system, such as accessing hardware functions and providing system information. 

BIOS Origins

American computer scientist Gary Kildall of Digital Research Inc. first introduced the term BIOS in 1975. BIOS was used first for a precursor to an operating system, Control Program/Monitor (CP/M). 

Key Milestones in the History of BIOS

• The introduction of the IBM 5150 Personal Computer in 1981 marked a significant milestone in BIOS history. IBM developed a standardised BIOS for their PC, which worked with the widely used Microsoft Disk Operating System (MS-DOS).
• Plug-and-Play (PnP) BIOS was introduced when Windows 95 was launched around 1995. This led to automatic device recognition and configuration without manual intervention.
• Advanced Configuration and Power Interface (ACPI) was released in 1996, aiming to replace PnP BIOS. ACPI allowed the operating system to communicate with the BIOS to control power-related functions, such as sleep modes and power-saving features.

Transition from BIOS to UEFI 

The BIOS can encounter difficulties when starting up and recognising multiple peripheral interfaces, such as USB, eSATA, Thunderbolt, as well as their associated devices, ports, and controllers on a modern PC.

Additionally, there is a limitation with BIOS versions where they are unable to boot from hard disks that have a storage capacity exceeding 2.2TB (terabytes). This means that if a hard disk larger than that is connected to a computer with such a BIOS, it may not be recognised as a bootable device during the startup process.

That’s why Intel started the ‘Intel Boot Initiative’ in 1998, which was later called Extensible Firmware Interface (EFI). Then, in 2006, when Apple made the transition to the Intel architecture for its Mac computers, it opted for EFI (Extensible Firmware Interface). However, other PC manufacturers did not adopt EFI and continued to use different firmware systems.

UEFI offers several advantages over legacy BIOS. 

• Enhanced pre-boot environment with graphical interfaces and mouse support.
• Support for larger hard drives and partitions through the GUID Partition Table (GPT) format.
• Secure Boot feature to protect against unauthorised firmware and operating system modifications.
• Faster boot times and improved system initialization.
• Advanced networking capabilities and support for protocols like IPv6.

Discover More Full Forms Quickly

• HTML Full Form
• ISP Full Form
• WWW Full Form
• API Full Form