Computer Startup and BIOS Overview

Introduction to BIOS

• Basic Input/Output System (BIOS): Initial software run when a computer starts.
  • Also known as firmware, system BIOS, or ROM BIOS.
  • Essential for system initialization even without storage devices or OS.
• Functions of BIOS:
  • Initializes system hardware components.
  • Performs a Power-On Self Test (POST) to check CPU, memory, and basic hardware.
  • Identifies storage devices for boot loader and OS loading.

Types of BIOS

• Legacy BIOS:
  • Over 25 years old, text-based interface.
  • Limited hardware support, no network or internet capabilities.
  • Direct hardware communication, though now largely replaced by device drivers.
• UEFI BIOS (Unified Extensible Firmware Interface):
  • Modern replacement for Legacy BIOS.
  • Based on Intel's Extensible Firmware Interface standard.
  • Supports larger storage systems and GUID Partition Table (GPT).
  • Includes pre-boot environment for troubleshooting without an OS.
  • Offers remote diagnostics and supports network communications.

BIOS Configuration Storage

• Nonvolatile BIOS Memory:
  • Stores configuration settings.
  • Traditionally used "Complementary Metal-Oxide-Semiconductor (CMOS)" memory.
  • Now primarily uses flash memory, no constant power needed.

Importance of the BIOS Battery

• Role of Battery:
  • Maintains BIOS settings and system date/time.
  • On older systems, a dead battery could lead to loss of settings.
  • Modern systems utilize the battery mainly for date/time maintenance.
• Resetting BIOS Settings:
  • On older systems, removing the battery could reset BIOS settings to defaults.

Practical Insight

• Finding the BIOS Chip:
  • Consult motherboard documentation to locate the BIOS chip.
  • Chip might be labeled directly on the hardware.
• Modern Developments:
  • Movement from Legacy to UEFI for enhanced capabilities and support.
  • Use of flash memory has improved reliability and flexibility in storing configurations.