Software is a set of instructions that controls computer processing and is classified into two categories. System software manages computer resources and includes operating systems, translators, and utility programs. Operating systems are responsible for resource management, file management, disk management, memory management, and security. There are various types of operating systems including DOS, Windows, UNIX, Linux, and others. Application software includes programs like word processors, spreadsheets, graphics software, and databases. Software is also classified based on its license type such as public domain, freeware, shareware, and commercial. Destructive software like viruses, worms, spyware, and others can also affect computer systems.

1. Introduction to Computers
Software

2. Functions of a computer
software means:
 a sets of instructions in the form of a program
 to control the processing of computer.
classified into two categories
Systems software
Applications software

3. System software
category of software, which manages all the
resources of computer
· Used by the computer to accomplish a task.
· Manages all the resources of computer
· Create database and keeps it update after every transaction
(Process Information : PID)
· Arrangement of files : Files System
· Controls the internal functions of computer : CPU
· Controls other devices connected to the CPUs : IO

4. Types of System Software
System software can be classified into :
1. Operating system
2. Translator (Assembles, Compilers, Intrepretors)
3. Utility programs

5. Functions of Operating System
(i) Resource Management :
Operating System is responsible for allocating various resources such as I/O
devices, memory etc.
(ii) File Management (FAT32, NTFS, Ext, Ext2, Ext3, JFS …
(iii) Disk Management : (Volumes, Partitions)
(iv) Memory Management:
Memory management software handles where programs put their current
data in RAM
(v) Security of data ( User Access Control)

6. Operating Systems
DOS, Windows 95,98, ….. XP , Win 7,8 ,10
UNIX
IBM – AIX
HP
SCO Unix
LINUX
Ubuntu
Redhat etc….

7. Types of Processing
Single user single tasking (DOS)
Single User, Multi tasking (win 95,98…..)
Multi User, Multi tasking (Unix, Win server editions)
Batch Processing
Real time OS (Hard, Soft)
Time Sharing Operating System

8. Application S/W
Eg:
1. Word Processing Package
2. Spreadsheet Package
3. Graphics Software, and
4. Database Management Software

9. Classification on the basis of License
1. Public Domain Software
2. Freeware
3. Shareware
4. Commercial Software (Proprietary)

10. Virus : Destructive Software
1. Trojans:
2. Worms
3. Spy ware
4. Zombie
5. Phishing
6. Spam
7. Browser hijacking (Session, Click-jacking)