System Software

System ↔ System ↔ Application ↔ Computer

User         Software        Software          System

System s/w is a collection of programs designed to operate, control and extend processing capabilities of computer and which makes the operation of a computer system more effective and efficient.

It comprises of
1.Operating system
2.Device driver
3.System utility
4.Language translators

Operating System

A collection of programs used to control and coordinate the computer system. It manages functions performed by hardware, I/O devices, CPU, Secondary storage devices, communication and n/w equipment.

Functions of operating system:

1.Memory management: It allocates and deallocates the memory of user prg.

2.Process management: Manages prg in execution. It schedules CPU and shares the CPU among many processes.

3.File management: Manages organization, naming, storing, retrieving, sharing and protection of
files.

4.Device management: Controls all the I/O devices and provides flexible and easy interface.

5.Security management: Protects the system resources and information against destruction and unauthorized access.

6.User Interface: It allows the user to give inst. And retrieve info. From the system.

Device Driver

• Special programs to extend the ability of OS in order to support I/O devices such as keyboard, mouse, monitor, printer…
  
• It contains all possible device dependent codes.
  
• It accepts request from device, translate it into commands for the appropriate device controller.
  

             Computer System    ↔  Device Driver  ↔   I/O Device
                                                         

• System utility
  

  • 
    
• Small prg having specific tasks to perform which helps the user maintenance of system
  
  

  • Functions of system utility:
    

  
  1.File management
  
  2.Backup
  
  3.Data recovery
  
  4.Virus protection
  
  5.Disk management
  
  6.Firewall
  
  7.Disk cleanup
  
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• Language Translator
  
  

  Tool that translates a programming language to m/c language which is understandable by a computer. 
  
  
  
  Categories of translators: 
  

  
  1.Compiler: Converts high level language to m/c level lang.
  or it converts source code (prg) into object code (binary form) as a whole. Compiler is unique for each lang.
  
  2.Interpreter: It converts source code (prg) into object code (binary form) as well as executes it line by line. It executes the statement before translating next statement.
  
  3.Assembler: Converts assembly lang prg into m/c lang prg.

  
  
  

  Flowchart of Compiler
  
  
      
  
  

  Flowchart of Interpreter
  
  

  
  

     
  
  

  Process of Assembler
  

  
  
  

  
  

  
  

    
  
  
  

  
  

  
  

  Types of OS
  
  
  

    
  
  
  

  
  

  
  
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