Operating Systems

Ubuntu : A Linux Distribution Operating System

Operating System

      Operating System is a System Software which is an Interface between Application software and Hardware also co ordinates between processor,input/output devices and Memory Allocation.Also is the first program to load into the memory after boot a computer.

Functions of an Operating System

• It is used as an easy to use interface for the User to the computer system.
• It assigns different tasks to the processor to be performed by the computer system.
• It allocated memory and storage for system programs, user applications and data.
• It coordinates between Input / Output Devices and their activities .
• It stores data in the form of files and helps in modifying them with the help of user applications and transferring data to other devices.
• It maintains Job priority.
• It transfer the control from one program to another program by the control signal from the user.
• It maintains data Security and Integrity.
• In case of errors it produces error messages and debugging codes.
• It maintains log of users in a Multi User Operating System.

Operating system as an Interface

Types Of Operating System

Single User Operating System

      Operating System which allows a single user at a time is Single User Operating System.

      Ex : MS-DOS.

Multi User Operating System

      Allows a number of users to work on a single computer.Users connect to the computer             the help of terminals.

      Ex : UNIX.

Single-Tasking Operating System

      OS which executes a single task at a time is called Single User Operating System.

      Ex : MS-DOS.

Multitasking Operating System

      Allows user to perform more than one job at the same time on a computer system.

      Ex : LINUX,UNIX,Windows.

Real-Time Operating System

      A real time operating system provides immediate processing and responds to user                   commands in real time or a very short period of time.Typically these are used in areas             like Aeroplane control ,Scientific Experiments,etc.

      Ex : HP -RT,VT-Works.

        

Network Operating System(NOS)

      NOS is a Multi User OS designed to support interconnection of several computers.NOS supports Multi User,Administrative,Network Management functions and responds requests of work stations, manage network access,resource allocation and sharing,data protection and error control also it provides printer , file, database and application sharing facilities. 

      Ex : Novell's Netware,Microsoft's Windows NT, etc.

Distributed Operating System

      A distributed operating systems runs on multiple computers interconnected by a network.In this Processes and system resources are managed globally and controlled from specific  locations.

Operating Systems Processing

1. Serial Processing : Programs are executed one by one.
2. Batch Processing : Multiple jobs are combined as a group and Executed at once.
3. Multi programming : Multiple jobs are loaded into the memory and executed based on                                                       priority with the help of spooling.

Spooling - Simultaneous Peripheral Operations On-Line :

      This is a  a kind of buffering by which slow process like printing is added to a queue for later processing .