BIOS (Basic Input/Output System)

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The BIOS firmware is the most basic software for PCs. It initiates and tests the hardware on the system, then loads a boot loader from the storage device to load and run the installed operating system. BIOS is the acronym for Basic Input/Output System, which originates from CP/M operating system that was used in the late 70s. BIOS was originally proprietary of IBM PC; then some other companies reverse engineered it.

The history of BIOS

The original BIOS applications from the early days of IBM PCs had no user interface; it was just delivering the error codes and the settings were changed via the jumpers and switches on the motherboard. The jumpers are simple conductive tools that bridge two pins on the motherboard. Then, by the beginning of the 90s, companies have begun including BIOS configuration utility/BIOS setup utility in the firmware; which are the ones that are generally known as just “BIOS” today.

How does BIOS work?

As the computer starts up, the power-on-self-test process (POST) begins, which tests and initializes the components of the PC such as CPU, chipset, RAM, GPU, keyboard, storage, integrated peripherals, and others. After that, the BIOS checks the boot loader software on the boot devices for their boot sectors; starting with the highest priority device, boots up the operating system if it has a boot loader software, or passes to the second-highest priority device if it has no boot loader installed.

The BIOS settings

BIOS configuration utility brought a primitive user interface that enables changing the settings of the firmware through the use of a keyboard. We are calling it “primitive”; in fact, it was a big improvement since the motherboards no longer needed that many switches and jumpers on their surface area which were eventually filled with other components.

The BIOS configuration interface generally can be reached by pressing the DELETE or F2 buttons. Then, users can change a variety of most basic settings that normally couldn’t be changed through the operating systems. Turning on and off the components on the motherboard, changing the speeds of the PCI slots, voltages and clock speeds of CPUs, latency settings of RAMs, and many more settings can be changed here. However, most AIO and laptop products have most of the BIOS settings locked; allowing only time and date settings as well as changing the boot devices’ priorities.

Does resetting CMOS delete BIOS?

The BIOS and its settings are generally stored on separate chips on the motherboard. Although, some companies have merged them. The BIOS settings chip, which is dubbed the CMOS RAM chip, is a nonvolatile memory that is backed up with a battery. Removing the battery while the motherboard had no power connected causes the loss of the settings. This “flaw” is often utilized by overclockers since it is an easy way to reset all of the settings.

Should I update my BIOS? Is it dangerous to update BIOS?

Updating the BIOS firmware is possible and is needed. Some motherboards might require BIOS updates to run the newer CPUs as well as some security or stability-related patch might be out. But a power loss during the updating process -mostly- ends up with bricked motherboard. Fixing this problem requires professional tools. The motherboard manufacturers have begun including additional BIOS chips in their high-level products to prevent this issue.

Today, BIOS is mostly replaced by UEFI firmware due to its limitations. UEFI provides much more features on a user-friendly interface that enables users to navigate through the menus by using a mouse as well.

What is a TPM device in BIOS?

TPM is the acronym for Trusted Platform Module. It generates, stores, and limits the use of cryptographic keys. It is mostly used for system integrity measurements. Currently, AMD and Intel have integrated TPM into their CPUs as firmware-based. TPM is strictly required by Windows 11.

What is AHCI mode in BIOS?

AHCI mode is a programming interface that brings additional functionalities to SATA storage devices such as NCQ and hot-plugging capabilities. Activating it also can bring some performance boost to storage.

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