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INTRODUCTION

The BIOS (an acronym for Basic Input Output System) software has a number of different roles, but its most important role is to load the operating system. BIOS is sometimes called firmware because it is an integral part of the system hardware. INTRODUCTION. About BIOS.

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INTRODUCTION

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  1. The BIOS (an acronym for Basic Input Output System) software has a number of different roles, but its most important role is to load the operating system. BIOS is sometimes called firmware because it is an integral part of the system hardware. INTRODUCTION

  2. About BIOS The BIOS is the default control for the most important functions of PC. It defines the compatibility of our PC with expansion hardware. Without it our PC couldn’t even boot.

  3. HISTORY • Before 1990 or so BIOSes were held on ROM chips. • BIOS firmware stored on EEPROM or flash memory devices. • To avoid BIOS corruption, some new motherboards have a backup BIOS ("Dual BIOS" boards). • Hardware manufacturers frequently issue BIOS updates to upgrade their products and remove bugs.

  4. WHATBIOSDOES? • A power-on self-test (POST) for all of the different hardware components in the system to make sure everything is working properly. • Activating other BIOS chips on different cards installed in the computer - For example, SCSI and graphics cards often have their own BIOS chips. • Providing a set of low-level routines that the operating system uses to interface to different hardware devices - It is these routines that give the BIOS its name. They manage things like the Keyboard, the Screen, and the Serial and Parallel ports, especially when the computer is booting. • Managing a collection of settings for the hard disks, clock, etc.

  5. POST • The first step of POST is the testing of the Power Supply to ensure that it is turned on and that it releases its reset signal. • CPU must exit the reset status mode and thereafter be able to execute instructions. • BIOS checksum must be valid, meaning that it must be readable. • CMOS checksum must be valid, meaning that it must be readable.

  6. POST(CONT…) • CPU must be able to read all forms of memory such as the memory controller, memory bus, and memory module. • The first 64KB of memory must be operational and have the capability to be read and written to and from, and capable of containing the POST code. • I/O bus / controller must be accessible

  7. ACCESSINGBIOS • Keys used to access the BIOS are"Esc," "Del," "F1," "F2," "Ctrl-Esc" or "Ctrl-Alt-Esc"key. • Power on the computer system and press the key to enter the BIOS after the beep for a clean POST is signaled. • If the procedure has been done correctly, the BIOS screen should be displayed rather than the typical boot screen.

  8. Common Options Includes :- • System Time/Date • Boot Sequence • Plug and Play • Mouse/KeyboardDrive Configuration • MemorySecurity • Power ManagementExit

  9. What Happens when System Boots?? • The BIOS reads sector 0 (known as the MBR - the Master Boot Record) from the first disk (or from floppy or CDROM), and jumps to the code found there - usually some bootstrap loader. • A bootstrap loader or bootstrapping or boot loader, is a program that resides in the computersEPROM,PROM, or otherNon- Volatile Memorythat automatically executed by the processor when the computer is turned on.

  10. EPROM

  11. PROM

  12. BOOT SEQUENCE • Check the CMOS Setup for custom settings • Load the interrupt handlers and device drivers • Initialize registers and power management • Perform the power-on self-test (POST) • Display system settings • Determine which devices are bootable • Initiate the bootstrap sequence

  13. CMOS • CMOS an acronym of Complementary Metal-Oxide Semiconductor is an on-board semiconductor chip powered by a CMOS battery inside computers that stores information such as the system time and system settings.

  14. Types of CMOS batteries Batteries used are – • External Lithium • Coin Cell • Barrel Style Solder • PS2 6v Life Time of a CMOS battery - Standard lifetime of a CMOS battery is around 10 Years.

  15. Flash memory • A form of non-volatile memory that can be electrically erased • Reprogrammable • Flash memory is used for easy and fast information storage • It is erased and programmed in blocks consisting of multiple locations . • Less costlier.

  16. TYPES OFBOOTING • COLD BOOT • WARM BOOT

  17. BIOS Boot Devices • A Boot Device is any device that must be initialized prior to loading the operating system. This includes : • primary input devices (keyboard). • primary output device (display). • Initial program load device (floppy drive, hard drive, CD-ROM,USB flash drive, etc).

  18. OVERCLOKING • Process of forcing a computer component to run at a higher clock rate than designed or designated by the manufacturer. • Boost a computer system's performance by increasing clock frequencies

  19. Advanced Configuration and Power Interface The Advanced Configuration and Power Interface (ACPI) specification is an open industry standard first released in December 1996 developed by HP, Intel, Microsoft, Phoenix and Toshiba that defines common interfaces for hardware recognition, motherboard and device configuration and power management. According to its specification[1], "ACPI is the key element in Operating System-directed configuration and Power Management (OSPM)".

  20. List of BIOS suppliers: • American Megatrends (AMI) • Phoenix Technologies • Award Software International (merged with Phoenix in 1998) • MicroID Research (MR BIOS) • Insyde Software (Insyde) • General Software (General Software)

  21. The Fall and Rise of the BIOS • Older operating systems such as DOS called on the BIOS to carry out most input-output tasks within the PC; with the introduction of newer operating systems such as Microsoft Windows and Linux, the BIOS was related to principally providing initial hardware setup, and bootstrapping. Once it was up and running, the operating system didn't have to rely on the BIOS for much. • In recent years, however, by way of systems such as ACPI, the BIOS has taken on more complex functions such as aspects of power management, hot plug, thermal management etc. This has led to renewed reliance on the BIOS by operating system producers, and an increase in complexity in the BIOS code

  22. .

  23. Top 6 Reasons To Upgrade BIOS AGP Video CPU Upgrading Large Hard Drive support Faster I/O Speeds Windows XP ACPI 2.0 Compliance Windows 2000 ACPI 2.0 Compliance

  24. LINKING TO HARDWARE • BIOS routines uses memory or I/O Ports to pass the commands and data to Hardware Devices. • In Memory Mapping a block of memory is used. • In I/O mapping I/O Ports are used .

  25. BIOS SETUP ENTRY POINTS

  26. FLASH BIOS • Better than EPROM • Can Encode the BIOS Program more quickly into Flash ROM than EPROM.

  27. BIOS SHORTCOMINGS Device Drivers Flash Laziness BIOS Shadowing Direct Control BIOS Bugs

  28. BIOS TROUBLESHOOTING • During POST BIOS generates two types of error messages – • Beep Codes. • POST Codes.

  29. GENERAL SYMPTOMS • BIOS Checksum Error – default loaded • CMOS Memory Size Mismatch • Data Error • CMOS Battery Failed • Hard Disk Failure • BIOS ROM Checksum Error –System Halted

  30. BIOS UPGRADE TROUBLESHOOTING • Flash Loader Utility Refuses to Run • Erase Chip Failure • Flash Chip Not Supported • System Refuses To Recognize Drives • Cannot Print Under DOS Or Windows

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