Explain BIOS

[Mathees]

Please explain to me how a BIOS works in detail.

 

Thanks in advance

 

Big Boi Mathis

[Riki M.]

BIOS (Basic Input/Output System) is a type of Firmware that is used to perform the hardware initialization during the boot-up process and it provides run-time services.

[minibois]

40 minutes ago, Mathees said:

Please explain to me how a BIOS works in detail.

BIOS stands for "Basic Input/Output System" and serves as the system running on your motherboard, to handle tasks such as setting CPU speed, memory speed, boot order (what drives to start up an OS from) and setting the time.

BIOS has been replaced with UEFI, which functionally for the user does the same.

 

There are a lot of different things you can do in the UEFI/BIOS, some of which I can detail here a bit:

Boot order: In said UEFI/BIOS a user will be able to set their boot order, so you can decide what drives to start up from first. Usually - when you just built a new system - you will have a USB drive with a Windows install on it and you will want to set that at #1 in the boot order, so the PC can start up from that. After installing Windows, you will want to alter the boot order, so the SSD you installed Windows on is now #1.

 

Memory overclocking: it is usually recommended to buy fast memory, think 3000Mhz or more. Many system will run the memory at a lower frequency by default, like 2133Mhz, 2400Mhz, etc. To enable the higher memory speeds, you need to turn on a feature that is often called "XMP" (or DOCP on ASUS AMD boards, or occasionally something else on the AMD side). This will make sure the memory is running at the higher speeds.

 

CPU overclocking: this is a feature that can have books written about them, it's this big of a subject. In short, you can make your motherboard tell your CPU to run faster, by editing certain parts of the UEFI/BIOS.

 

There are a lot more things I could go into detail about, but that depends on the scope you're looking for.

For most novice builders I recommend:

- Alter the boot order to have your USB drive as #1

- Install Windows

- Go back to the UEFI/BIOS, enable XMP and set your SSD as boot order #1

- Ensure everything works

- Overclock your CPU (if you are interested in that).

 

The specifics of what feature are or are not available (such as CPU/memory overclocking) may depend from one motherboard to another.

[straight_stewie]

UEFI/BIOS and ACPI provide an abstraction level on top of hardware that the operating system can use to interact with said hardware.

It is additionally responsible for system and component initialization, among other things.

For specifics on how these work, what they do and how they do it, you can read the de-facto specifications here:

https://www.uefi.org/specifications