POST, BIOS, CMOS and UEFI Flashcards
What does BIOS stand for?
Basic Input/Output System.
What does POST stand for?
Power-on Self-test.
What happens when a computer is booted?
The BIOS performs a hardware check on the main components of the computer. This is called a POST.
If there is a problem at bootup, then what is the likely outcome?
Either the computer emitting a series of beeps, or the screen goes blank and the beeps are emitted.
This error code indicates there is a hardware problem.
Are the error codes uniform across different BIOS?
No. There are usually similarities, however, motherboard manufacturers tend to use many different codes. Always consult the documentation.
What is a safe method of determining whether or not the POST is functioning correctly?
Remove the RAM modules from the computer, then power it on. It should emit the error code, but not damage your computer.
What is BIOS?
BIOS is a ROM chip on the motherboard that contains a small program. This program controls the communication between the operating system and the hardware.
What do POST/BIOS do together?
They identify:
Which drives are available.
Which drives are bootable.
How the memory is configured and when it can be used.
How PCIe and PCI expansion slots are configured.
How SATA and USB ports are configured.
Motherboard power management features.
Where are the BIOS settings stored?
In a Complimentary Metal Oxide Semiconductor chip.
CMOS Chip
How are BIOS settings retained by the CMOS?
The CMOS is battery powered. However, if the battery fails then settings can be lost. To this end it is always recommended that the BIOS settings be documented.
What is an easy way of documenting the BIOS settings?
By simply taking a picture of them.
What could the computers time and date being incorrect mean?
That the CMOS battery is bad or getting low.
What does UEFI mean?
Unified Extensible Firmware Interface.
What booting system do new computers utilise?
They use UEFI with legacy BIOS. This is because is provides additional features whilst addressing security issues with base BIOS.
Why may you see BIOS/UEFI when booting your BIOS?
Because Intel chips currently support backwards compatibility with legacy BIOS. They will stop with this practice past 2020.
