Rememberthat the PC cannot do anything unless it receives instructions.Instructions are fragments of programs which are loaded into the CPU, and theCPU starts by executing the system software which is stored on the motherboard.Later, once the PC is up and running, the operating system can fetchinstructions (programs) itself from the hard disk; but during startup, the CPUis fed instructions from the ROM code in the motherboard.
Thelast link in the startup process is that the BIOS looks in the CMOS storage tofind the chosen boot device. Normally it has to boot from one of the harddisks, and the BIOS thus has to read the contents of the master boot record(which is a particular sector on the hard disk). It then continues by loadingthe operating system from the hard disk, and the startup programs have playedout their role.
Today theBIOS is still a collection of program fragments which establish connections tocertain hardware devices. The BIOS is still available to programmers, but theWindows operating system prefers to use its own drivers to communicate withhardware. Thus Windows has two ways of accessing each hardware device:
I havealready mentioned that the Internet is a good source of knowledge on ITsubjects. There are an incredible number of English language sites, whichspecialise in describing, analysing and commenting on various hardware itemssuch as motherboards, processors, etc.
ESCD. Extended System ConfigurationData. A list of the installed PCI devices. Included in the CMOS storage. File system. A system for organising data atthe sector level on, for example, a hard disk. E.g. FAT32, NTFS.IDE. Integrated Drive Electronics. Harddisk interface. IrDA. Infrared Data Association.Standard for wireless data transfer over short distances using infrared light(like your TV remote control).