BIOS

BIOS (Basic Input/Output System) Overview

1. What is the BIOS?

BIOS (Basic Input/Output System) is firmware embedded in a small memory chip on a computer’s motherboard. It is responsible for initializing hardware components and loading the operating system (OS). The BIOS provides an interface between the OS and the hardware.

2. Timeline of BIOS Evolution

  • 1975: Created by Gary Kildall as part of CP/M (Control Program for Microcomputers).
  • 1981: IBM PC introduced the first widely used BIOS.
  • 1990s-2000s: BIOS became a standard in IBM-compatible PCs.
  • 2006: UEFI (Unified Extensible Firmware Interface) was introduced to replace BIOS.
  • Present: UEFI has largely replaced BIOS, offering more features like Secure Boot, graphical UI, and support for larger storage.

3. Where is BIOS Used?

BIOS is used in:

  • Desktops & Laptops: To initialize hardware before loading the OS.
  • Embedded Systems: Some devices, like industrial controllers, still use BIOS-like firmware.
  • Older Legacy Systems: Many older computers rely on BIOS since they do not support UEFI.

4. How to Access BIOS?

You can access the BIOS during the boot process by pressing a specific key before the OS loads. Common keys include:

  • DEL or F2: Most desktop and laptop motherboards.
  • F10: HP devices.
  • F12: Some Lenovo and Dell systems.
  • ESC: Some ASUS and Toshiba laptops.
Steps to Enter BIOS:
  1. Restart the computer.
  2. Immediately press the designated key repeatedly before the OS loads.
  3. Navigate using the keyboard (arrow keys, Enter, ESC) or mouse (on newer UEFI systems).
  4. Adjust settings like boot order, hardware configurations, or security options.

5. Advantages and Disadvantages of BIOS

Advantages:

  1. Hardware Initialization: Ensures hardware components are working before booting the OS.
  2. Boot Device Selection: Allows users to select boot priority (HDD, SSD, USB, CD/DVD).
  3. Basic Troubleshooting Interface: Provides low-level access to diagnose hardware issues.
  4. Legacy Support: Works with older operating systems and hardware that do not support UEFI.

Disadvantages:

  1. Limited Storage Support: Cannot boot from drives larger than 2TB.
  2. Slower Boot Time: Lacks optimized startup processes compared to UEFI.
  3. No Secure Boot: More vulnerable to boot-level malware and rootkits.
  4. Keyboard-Only Interface: No mouse or graphical UI, making navigation harder.
  5. Outdated Technology: UEFI has largely replaced BIOS in modern systems.

6. BIOS Troubleshooting Guide

If you encounter BIOS-related issues, follow these troubleshooting steps:

 Computer Not Booting (Stuck on BIOS Screen)

Solutions:

  • Check if the boot order is correct (ensure the hard drive or SSD is the first priority).
  • Disconnect any external devices (USB drives, external hard drives) and restart.
  • Reset BIOS settings to default factory settings (option available in BIOS).
  • Check for hardware failures (RAM, CPU, or motherboard issues).

BIOS Not Detecting Hard Drive

Solutions:

  • Verify the SATA/IDE cables are securely connected to the motherboard and hard drive.
  • Enter BIOS and check if the SATA mode is set correctly (AHCI/IDE).
  • Try switching to another SATA port on the motherboard.
  • If using an NVMe SSD, ensure UEFI boot mode is enabled.

Unable to Access BIOS

Solutions:

  • Try a different BIOS key (DEL, F2, F10, F12, ESC) as it varies by manufacturer.
  • Use the “Restart to Firmware Settings” option in Windows Advanced Startup:
    • Open Settings > Update & Security > Recovery > Restart Now.
    • Go to Troubleshoot > Advanced Options > UEFI Firmware Settings > Restart.
  • If BIOS is locked with a password, reset it by removing the CMOS battery for 5-10 minutes.

BIOS Update Failed

Solutions:

  • If the system does not boot, check if the manufacturer provides a BIOS recovery mode.
  • Try reflashing the BIOS using a USB recovery tool provided by the motherboard vendor.
  • Do not power off the system during BIOS update, as it may brick the motherboard.

Overclocking Issues / System Instability

Solutions:

  • If the system crashes after overclocking, reset BIOS to default factory settings.
  • Reduce overclocking frequencies for CPU and RAM.
  • Ensure proper cooling to prevent overheating.

CMOS Checksum Error

Solutions:

  • Replace the CMOS battery (CR2032) on the motherboard.
  • Reset BIOS to default settings and restart the computer.
Previous Lesson
Back to Lesson
Next Topic