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

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

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

4. 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

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

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

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

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

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

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

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

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

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

14. 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

15. 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

16. 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

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

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

19. Popular WP packages
WordPerfect
MS word
WordStar
Mac Write
MultiMate