The Operating system Gives life to the hardware Firmware built into the computer run special software – known as software

Functions of OS Providing use interface Managing the hardware devices Managing and maintaining the disk files Supporting – running application programmes

Components of OS and its functions Bootstrap programme Diagnostic programme Monitor programme BIOS programme Utility programme File maintenance programme

Bootstrap programme Usually contained on the ROM memory Task – to load the main portion of the OS in to the main memory Known as booting the computer

Diagnostic programme Test the operation of the system components One programme may check the disk , other may check RAM

Monitor programme Monitor and control the activities of various units and assign tasks to them Also known as operating system executive

BIOS programme Contains number of sub programmes that control some basic input/output devices

Utility programme Formatting the disk Copying the contents of a disk Determining the space available in a disk

File maintenance programme Maintain the files on the secondary storage units attached to the computer

Types of OS system Batch OS Multi-user OS Multitasking OS Multiprocessing OS On-line OS Real-time OS

Batch OS The system reads the job, process it and when completed goes to the next job Most early computer used this OS

Multi-user OS Allow more than one user to access and use the computer The CPU time is shared by the users simultaneously

Multitasking OS Ability of an OS to handle more than one task at a time Multimedia applications requires OS with multitasking capabilities

Multiprocessing OS OS that can mange s series of CPUs working together is known as multiprocessing OS Increases overall power of the computer Also called parallel processing system

On-line OS The computer system in on-line and the programme that is used to process the data resides in the internal memory continuously The system executes programmes as and when the data is available Used in railway reservation system

Real-time Os There are situations where computers are used to control some physical systems such as process control system. In such system a computer operates in real time, that is the computer receives signals process tem instantly and takes control action immediately

Popular OS MS- DOS Windows –95, 98, 2000, XP Windows NT Unix

Application of Word processors Repetitive letters Standard documents Special reports Financial reports

Popular WP packages WordPerfect MS word WordStar Mac Write MultiMate