3.8.1 BIOS/UEFI

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does UEFI stand for?

Universal Extended Firmware Integration

Unified Executable Firmware Interface

Unified Extensible Firmware Interface (correct)

Unified External Firmware Interface

Which of the following provides better security against bootkit attacks?

EEPROM

CMOS

UEFI (correct)

Legacy BIOS

What has replaced CMOS chips in modern devices?

EEPROM (correct)

BIOS

RAM

Flash Memory

What limitation does UEFI improve over legacy BIOS?

Supports drives larger than 2.2 TB Signup and view all the answers

Why can't the CPU load software directly from RAM or disk?

It lacks the necessary instructions. Signup and view all the answers

What is the function of a ROM chip on a motherboard?

To store the necessary instructions for hardware communication Signup and view all the answers

Which of the following statements about EEPROM is true?

It allows updating of BIOS without removing chips. Signup and view all the answers

What role do BIOS and CMOS play in a PC system?

They enable communication between the CPU and other devices. Signup and view all the answers

What is the primary purpose of the CMOS battery?

To keep the clock running when the computer is off Signup and view all the answers

What type of memory is EEPROM, and how does it relate to BIOS settings?

It is a type of flash memory that retains BIOS settings after shutdown. Signup and view all the answers

How are BIOS and CMOS settings typically referenced in the industry?

They are often used interchangeably, though this is technically incorrect. Signup and view all the answers

What can be modified using the CMOS setup program?

The parameters that the BIOS software needs to function Signup and view all the answers

Which statement correctly describes the relationship between BIOS and CMOS?

CMOS settings can save custom parameters while BIOS cannot. Signup and view all the answers

What might happen if the CMOS battery is removed or fails?

The clock will reset, requiring manual adjustment. Signup and view all the answers

Why do we still need a CMOS battery in modern systems?

To maintain the date and time settings. Signup and view all the answers

What was the relationship between BIOS chips and CMOS chips in older systems?

They were implemented as two separate chips on the motherboard. Signup and view all the answers

What is a key feature of a ROM chip compared to a RAM chip?

It retains its contents when the system is powered off. Signup and view all the answers

What is the collective name for the hundreds of programs stored on a ROM chip in a PC?

BIOS Signup and view all the answers

Which type of devices can be handled by the BIOS alone?

Non-configurable Devices Signup and view all the answers

What type of memory do EEPROM chips correspond to?

Random access memory Signup and view all the answers

What do the programs in the CMOS provide to the BIOS?

Configuration parameters for devices Signup and view all the answers

Which type of device might require the use of Option ROM?

Sound card Signup and view all the answers

What is a primary reason for using device drivers instead of BIOS for certain components?

BIOS cannot communicate with custom devices. Signup and view all the answers

What happens to the information stored in RAM when the PC is powered off?

It is lost. Signup and view all the answers

Which of the following is NOT a characteristic of ROM?

Can be rewritten. Signup and view all the answers

Why can't the BIOS handle configurable devices alone?

Their parameters frequently change. Signup and view all the answers

Which of the following statements about the CPU’s interaction with devices is true?

The CPU uses both BIOS programs and device drivers to communicate. Signup and view all the answers

What is stored in the ROM chip that is essential for system function?

Basic input-output services Signup and view all the answers

Study Notes

BIOS and CMOS Overview

BIOS and CMOS are not single entities, but rather a combination of UEFI, legacy BIOS, CMOS, and EEPROM.
UEFI (Unified Extensible Firmware Interface) replaced older BIOS designs, improving software interoperability, addressing limitations, and enhancing security.
UEFI offers faster boot times, support for larger drives, and 64-bit drivers.
Legacy BIOS still exists in some PCs.
"BIOS" is now a general term encompassing both UEFI and legacy BIOS.
CMOS is also a generic term, historically referring to chips now replaced by EEPROMs.
EEPROM (Electrically Erasable Programmable Read-only Memory) is a non-volatile memory, replacing EPROMs, allowing in-place BIOS updates since 1994.

CPU-Device Communication

CPUs cannot directly communicate with devices like RAM and storage.
Software instructions are needed.
Software cannot be loaded from RAM or storage directly: the CPU doesn't initially know how to communicate with these components.
ROM (Read-Only Memory) chips solve this, containing programs to manage CPU-device communication.

ROM (Read-Only Memory)

ROM chips retain data even when power is off (persistent data).
RAM loses data with power loss.
ROMs are pre-programmed at the factory with programs.
ROM programs for device communication are called the BIOS.
BIOS is the software on the ROM chip, not the chip itself.
ROM chips in PC systems are typically 365 KB to 1 MB in size.

Device Categories

Devices are categorized into non-configurable, configurable, and custom devices.

Non-Configurable Devices

BIOS handles these devices because parameters are fixed.
Examples: keyboard, internal PC speaker.

Configurable Devices

Parameters can change; BIOS alone is insufficient.
Examples: RAM, hard drives (sizes vary).
EEPROM (or CMOS) chips are used to store configurable parameters.
These allow adding/changing hardware without BIOS replacement.

Custom Devices

Devices like sound cards, network cards, and video cards are numerous and varied.
BIOS cannot account for all possibilities.
Two strategies to handle custom devices:
- Option ROM (OPROM): Firmware on plugin cards or system boards that provide drivers for particular devices (e.g., video cards, RAID controllers).
- Device drivers: Software loaded by the operating system; tell the CPU how to interact with custom hardware.

CMOS (Complementary Metal-Oxide-Semiconductor)

CMOS is RAM used to hold configuration data needed by BIOS programs.
BIOS has programs for communication.
CMOS stores configuration data like drive parameters.
BIOS programs access CMOS for this data to address new devices; thus, enabling the system to manage the newly added hardware.
CMOS stores system clock information.
Older CMOS required a battery (CMOS battery) to retain settings during power-off. Modern systems use EEPROM (flash) instead, which are not affected by power loss.
CMOS battery is still needed to provide power to the system clock.

BIOS Settings vs. CMOS Settings

Historically, BIOS and CMOS were separate chips.
Now, they are often on the same chip, leading to the terminology confusion.
BIOS cannot be rewritten; it's read-only.
CMOS data allows customizing hardware parameters.
CMOS setup programs allow modifying CMOS data.

Summary

CPUs need software to communicate with devices.
BIOS/UEFI provides this software.
CMOS (or EEPROM) stores configurable parameters for devices.
Device drivers handle custom devices.
A CMOS battery maintains the system clock.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the intricacies of BIOS, CMOS, and UEFI. This quiz delves into the evolution of these systems and their impact on PC functionality, including their roles in communication between the CPU and other devices. Test your knowledge of these essential components in modern computing.