BIOS/UEFI Lesson 002: Boot Options

What does the BIOS manage?

Data flow between the OS and other devices

What functionalities does the BIOS manage?

The power-on self-test, hardware configuration, and the boot order setup.

Read-Only Memory (ROM) Chip

The type of chip embedded in the motherboard and can be upgraded through flashing and is where the BIOS is stored.

Complementary Metal-Oxide Semiconductor (CMOS)

A battery-powered non-volatile memory chip where date, time, BIOS settings configurations are stored.

Complementary Metal-Oxide Semiconductor (CMOS) Battery

The battery that powers the CMOS.

What is an indication that the CMOS battery needs to be replaced?

The date and time keep resetting to factory settings.

How long can a CMOS battery last?

3 years minimum, but up to 10 years on more modern systems.

What type of battery is the CMOS battery?

CR2032 3 volt cell battery.

Power-On Self-Test (POST)

A diagnostic testing sequence run by BIOS to check if the hardware is working properly.

How does the POST communicate if something is wrong?

Usually with a message on the display or through a series of coded beeps if that is not an option.

What can cause the POST to halt the boot process?

If there is anything wrong with the memory, keyboard, I/O devices, or the processor.

How does one configure BIOS settings?

Through the BIOS configuration environment.

What advantages does UEFI have over BIOS

Can support 64-bit systems, large SSDs and HDDs, with faster boot-up time and larger ROM for complex tools.

Master Boot Record (MBR)

This is what BIOS uses as a storage device partition table, which tells the user how things are stored on a storage device.

Globally Unique Identifier (GUID) Partition Table (GPT)

Supports larger storage decives that are larger than 2.2 terabytes (TB).

How big of a drive can BIOS support?

Up to 2.2 terabytes (TB).

How big of a drive can UEFI support?

9.4 zettabytes (ZB).

Preboot eXecution Environment (PXE)

A standard for booting computers over a network from a server, eliminating the need for physical storage devices for boot-up.

What would you most likely use to configure the preboot eXecution environment?

The BIOS boot option.

Where can one obtain an operating system to boot up?

On any internal or external storage device or through a network using PXE.

What is the best practice to ensure that data on a computer cannot be accessed from a different OS on a computer.

By disabling booting from optical or USB drives to prevent system takeover by attackers, and to configure the system to boot from the installed hard drive using the installed OS.

Flashing

Performed during upgrades, security fixes, or feature improvements.

How was BIOS firmware updated on legacy systems?

By replacing the entire chip on the motherboard.