Introduction to BIOS
- The BIOS (Basic Input Output System) is the first software that runs when you start
your computer, appearing before the operating system loads.
- Also referred to as firmware, system BIOS, or ROM
BIOS (historically stored in Read-Only Memory).
- Modern systems store the BIOS in flash memory on the motherboard, allowing for
updates.
- The BIOS initializes hardware and prepares the system to load the operating system.
Power On Self Test (POST)
- The POST (Power On Self Test) is the diagnostic process performed by the BIOS
during startup.
- Checks for essential hardware components, including:
- CPU
- Memory (RAM)
- Keyboard and mouse
- Storage devices
- If any critical hardware fails initialization, an error message or beep code is
displayed.
- The POST process typically completes within a few seconds before proceeding to load the operating
system.
Bootloader and Operating System Selection
- After POST completes, the system either:
- Automatically loads the operating system, or
- Displays a bootloader prompt to select an operating system (if multiple are
installed).
- The bootloader signifies that POST has finished and the system is ready to load the OS.
BIOS Storage and Redundancy
- Modern motherboards store the BIOS in flash memory, enabling updates and
modifications.
- Some motherboards include dual BIOS chips (main and backup) to prevent failure
during updates.
- If an update fails, the backup BIOS can restore functionality.
Legacy BIOS
- Used in older systems (over 25 years old) and designed for legacy hardware.
- Limitations include:
- Lack of support for modern hardware components.
- Text-based interface requiring keyboard navigation (no mouse support).
- Limited configuration options compared to modern alternatives.
- Common features:
- Function keys or number keys for navigation.
- On-screen prompts for available actions.
UEFI BIOS
- UEFI (Unified Extensible Firmware Interface) is the modern standard for BIOS,
replacing legacy BIOS in newer systems.
- Developed by Intel but adopted as an industry standard, ensuring consistency across manufacturers.
- Key features:
- Graphical user interface (GUI) with mouse support.
- Enhanced hardware compatibility for modern components.
- Advanced configuration options for performance, security, and virtualization.
- Common UEFI settings include:
- CPU and BIOS overview.
- Connected devices (storage, audio, network).
- Advanced settings (virtualization, CPU features).
- Power management and security options.
- Boot order and startup configurations.
- Some settings are critical for system stability; modifications should be made with caution.
BIOS Updates and Best Practices
- BIOS updates can improve hardware compatibility, security, and performance.
- Best practices for updating BIOS:
- Backup current BIOS settings before updating.
- Follow manufacturer instructions precisely.
- Ensure a stable power source during the update process.
- Use the backup BIOS (if available) in case of failure.
- Incorrect updates can render a system inoperable; proceed with caution.