Lecture 1: Network Operating Systems (NOS) An Introduction

What is an Operating System? 2 kinds of a software – Application Software Word processors, database manager, compiler, web browser – System Software Operating system itself Bridges between the hardware and users

Functions of Operating Systems (OS) Resource management Memory management Device management – Printer – Hard drive – display Process management Processor management (CPU time )

Operating Systems (OS) : Examples

Why OS was Born? Batch processing – Resident Monitor

Time Sharing Using Operating Systems

Operating Systems  An operating system (OS) is software that manages computer hardware and software resources and provides common services for computer programs.  Operating systems form an essential component of the system software in a computer system. Application programs usually require an operating system to function.  Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources.

Operating Systems  For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and will frequently make a system call to an OS function or be interrupted by it.  Operating systems can be found on almost any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers.

Operating Systems: Examples  Examples of popular modern operating systems include:  Android, BSD, iOS, Windows Phone,  Linux, OS X, QNX,  Microsoft Windows, and IBM z/OS.  All these examples, except Windows, Windows Phone and z/OS, share roots in UNIX.

Networks Operating Systems  Network operating system refers to software that implements an operating system of some kind that is oriented to computer networking.  For example, one that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions.  The network operating system is designed to allow shared file and printer access among multiple computers in a network,  typically a local area network (LAN), a private network or to other networks.

Networks Operating Systems: Where to use?  NOS can be used in:  Routers, switches and hardware firewall.  PCs in Peer-to-peer networks  Client-server Architicture