BIOS

Accessing System BIOS

• You can use the System Setup utility to change variable BIOS information, such as the type of hard drive you have installed on your system.

• You can access the System Setup utility when you boot the computer. Just follow the on-screen instructions when you first power up.

Function of the System BIOS

• The BIOS determines how the various devices in the PC and the CPU communicate.

• The system BIOS is saved on a special chip on the motherboard called the flash BIOS chip.

• BIOS stored in the flash ROM can be updated. Updating enables a motherboard to access new technologies that it was not originally designed to support.

Three primary functions of BIOS

• Boots the computer• Verifies the information providedoInternal and peripheral devices

connected to the computer• Serves as the interfaceoBetween the hardware and

software

BIOS Manufacturers • Award• AMI (American Megatrends, Inc.)• Phoenix

o 80 percent of all Intel motherboards oAward was bought by Phoenix (1998)

BIOS in Action • The instructions used to start up a PC

and load the operating system• Boot sequence or booting the

computeroThe process of starting the PC

• Boot means “pulling one’s self up by one’s own bootstrap” or being able to start up by itself

Types of BIOS Chips • ROM (read only memory)

o Type of memory that cannot be alteredo Non-volatileo Commonly called ROM BIOS

• PROM (programmable read only memory)o Blank ROM that must be programmed with data

you want it to storeo Using a ROM burner or ROM programmer

• EPROM (erasable programmable read only memory)o Data can be erased and reprogrammed

• EEPROM (electronically erasable programmable read only memory)o Somewhat similar to EPROM but it doesn’t need

to be removed from the boardo Updating the BIOS EERPOM is called flashingo Commonly called Flash ROM

Types of BIOS Chips • CMOS (complementary metal oxide semiconductor)

o Aka NVRAM (non volatile RAM)o Powered by lithium battery or dry cell

• Unified Extensible Firmware Interface (UEFI)o is a specification that defines a software interface

between an operating system and platform firmware

o meant to replace the Basic Input/Output System (BIOS) firmware interface, originally present in all IBM PC-compatible personal computers

o In practice, most UEFI images provide legacy support for BIOS services. UEFI can support remote diagnostics and repair of computers, even without another operating system

o The original EFI (Extensible Firmware Interface) specification was developed by Intel.

Cold boot vs Warm boot

• Cold booto The boot sequence used after the PC is

powered on from a powered-off state• Warm boot

o PC is powered on and reset

POST Process POST (Power On Self Test)

Checks all system component and hardware listed in the system setup

BIOS beep codes • IBM BIOS beep codes

BIOS beep codes • AMI BIOS beep codes

BIOS beep codes • Award BIOS beep codes

BIOS beep codes • Phoenix BIOS beep codes

BIOS start-up screen• Name of the BIOS manufacturer and the

version number of the BIOS• Release date or version date of the BIOS• Keyboard key used to access the BIOS

setup program• Logo

oBIOS manufacturer, PC manufacturer, motherboard manufacturer

• Energy star logo• Serial number of the BIOS

BIOS Access keys