A network is a group of two or more computer systems sharing services and interacting in some manner In the end Computer network are mainly divided into Local
A computer network is a collection of interconnected computers and other devices which are able to communicate with each other and share hardware and software
Introduction -A network can be defined as a group of computers and other devices connected in some ways so as to be able to exchange data
A personal area network (PAN) is a computer network used for communication among computer and different information technological devices close to one person
When we create a network of different devices, it is called networking Page 3 COMPUTER NETRWORK • A computer network is a collection of computers and
A computer network consists of a collection of computers, printers and other equipment that is connected together so that they can communicate with each other
Here we use the public Internet, a specific computer network, as our principle vehicle for discussing computer networking protocols But what is the Internet?
This network consists of group of computers along with its connecting devices that has a common communications channel In this there will be only one main
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INTRODUCTION TO
COMPUTER
NETWORKING AND
OPERATING SYSTEM
Chapter No. ONE
By
Dr. Yasir Zafar Khan
Computer Science Faculty
$08 *LUO¶V 6ŃORRO $08 iec.ice@gmail.com
INTRODUCTION
Networking refers the inte-connection of various devices to share their resources. A network is an inter-connection of machines or people. A network is a group of devices connected with one another. Cable television networks and telephone networks are examples of networks. When we create a network of different devices, it is called networking.
COMPUTER NETRWORK
A computer network is a collection of computers and peripheral devices such as printer connected communication links. To establish a computer network, we need at least two computers and some other devices. These devices are interconnected using a communication medium such as wire. The communication media or links allow the network components to work together. The network components may be located at remote locations or within the same building.
NEYWROK BENEFITS
¾ Many companies and individual
have discovered that there are several benefits of connecting computers together.
¾ Network can improve the work by
increasing productivity, lowering costs etc. Ease of Access Work from Home Sharing Resources Sharing Information Productivity Programs Cost Administration Security
HARDWARE REQUIRED
TO
ESTABLISHED NETWORK
9 COMPUTERS
IBM-Compatible and Macintosh
Computers connected to a network need not to be
of the same type.
9 CABLE
Ethernet, twisted pair, Co-axial Cable and Optical fiber. Cables are wires that connect computers and resources on a network.
9 CONNECTORS
RJ-45 connectors
A connector is a device that joins two computers
or networks together.
9 NETWORK
Network Interface Card (NIC)
Is a Device that join a cable to a computer.
TYPES OF NETWORK
¾ PERSONAL AREA NETWORK (PAN)
A PAN is a computer network used for communication among various electronic devices VXŃO 3G$·V 3HUVRQMO GLJLPMO $VVLVPMQPV
Mobile Phones in close proximity.
The area of PAN is typically a few meters.
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PAN can be used for communication among the
devices or for connecting to the internet.
A PAN may use wireless connection as well
Example of PAN: Home and School
¾ LOCAL AREA NETWORK(LAN)
A LAN is the most common type of network.
A LAN connects computers and devices located
close to one another, such as in one building.
Usually LAN has not more than 100 computers.
Example of LAN: Computer Lab of your school, CCTV Network
¾ CAMPUS AREA NETWORK (CAN)
A CAN is a computer network made of an
interconnection of two or more I$1·V RLPOLQ M limited area. A CAN is larger than a LAN but smaller than WAN.
Example of CAN: A University, College,
School or Shopping Mall
¾ METROPOLITAN AREA NETWORK (MAN)
A MAN is also a collection of LAN.
MAN connects computers located in the same
geographical area such as city or town.
Example of MAN: Cable network, Banks
¾ WIDE AREA NETWORK (WAN)
A WAN connects local and metropolitan are
network together.
The Networks that make up a WAN, may be
located throughout a country or even around the world.
Example of WAN: Internet
NATURE OF COMPUTER NETWORK
Two types of nature of computer network are:
PERMANENT NETWORK
Most companies use a permanent network to transfer information. A permanent network uses cables to link computers together. The computers and cables on a permanent network stay connected and in place at all times.
TEMPORARY NETWORK
A temporary network is a network connection that is established for a brief period of time and disconnected.
The most common type of temporary network
occurs when a n employee connects a computer at home to a computer at work in the office using a modem.
NETWORK TOPOLOGY
The art of connecting different
computers in a network is known as topology.
The term network topology refers to
the way in which the nodes of a network are linked together. There are three basic topologies are:
9 STAR TOPOLOGY
All nodes are connected to a central system called switch, which forwards data towards its final destination. The switch controls the communication on the network.
Star topology has minimal line cost (Advantage)
If any of the local computers fails, the remaining portion of the network is unaffected. (Advantage) The system crucially depends on the central switch. (Disadvantage) If it fails, the entire network goes down. (Disadvantage)
9 RING TOPOLOGY
The nodes are connected in a closed loop so that
each devices is connected to two others, one either. The computers in a ring topology are connected in the shape of closed ring. Data are simple passed from one machine to another.
Data travel only in one direction in a ring.
Each computer passes the data to the next one on
the line automatically. The ring works well where there is no central-site computer system (Advantage) It is more reliable than a star network. (Advantage)
The ring network requires more complicate
control software. (Disadvantage)
9 BUS TOPOLOGY
All of the nodes are connected to central cable called bus.
A bus is single continuous cable.
Transmission from any node travels the length of
the bus in both directions and can be received by all other nodes. The bus has terminators at either ends which absorbs the signal, removing it from the bus.
It is quit easy to set.
Failure of one node does not affect the rest of the network.
It offers limited flexibility for change.
A signal on the bus must be strong enough to reach the receiver.
OPERATING SYSTEM
The operating system, also referred to as the OS, is a computer program that manages all the other programs on your computer, stores files in an organized manner, and coordinates the use of the computer hardware such as the keyboard and mouse The operating system frees one from having to interact directly with the hardware³other than clicking the mouse button or pressing keys on the keyboard³ to complete tasks.
VARIOUS FUNCTIONS OF OPERATING
SYSTEM
MEMORY MANAGEMENT FUNCTION
Operating System manages the primary memory of the system. It allocates the memory, on the request of process, which is being run @ that time. It also keeps a check @ a particular time, how many bytes of memory are in use and which process is using it. It also keeps track of what part of it is free. In case of multi-user system, it decides on the propriety basis, that which user will have access to memory & when. How much of it is used depends on the requirements.
File Management Function
Writing & retrieving the information on/from the secondary storage device is the function of an
Operating system.
It follows a complete methodology for maintaining the files, so that different sets of information do not get mixed up and exactly the same set of information is supplied, which is required by the user.
Processor Management Functions
Operating System also takes care of the processor It allocates the processor. In case of multi-user system, it allocates the processor time to different users as and when needed & in such a way that every user has a minimum time.
Device Management Function
It keeps track of all the devices i.e. peripherals attached to the computer such as I/O devices etc. When needed, it allocates the devices in such a way that can be efficiently used. It initiates the I/O operations & allocates them along with other devices to the user. It initiates the I/O operations & allocates them alongwith other devices to the user.
TYPES OF OPERATING SYSTEM
SINGLE USE OPERATING SYSTEM
These Operating Systems allows only user
to work on a computer at a time.
Example: MS-DOS, CP/M
MULTIUSER OPERATING SYSTEM
These Operating system allow more than one user to work on the computer at the same time. These operating systems allocates memory in such a way that different users can work simultaneously without disturbing each other. It also allocates the processing time in such a way that every user gets a very quick response from the machine. These are also known as Time Sharing
Operating System.
Example: UNIX, XENIX, VMS and
Windows NT
MULTITASKING OPERATING SYSTEM
The ability to execute more than one task at the same time, a task being a program. The terms multitasking & multiprocessing are often used interchangeably, although multiprocessing sometimes implies that more than one CPU is involved. In multitasking sometimes, only one CPU is involved, but it switches from one program to another so quickly that it gives the appearance of executing all of the programs at the same time. There are two basic type of multi-tasking:
Preemptive
9 The Operating system parcels out CPU time slices to
each program.
9 OS/2, Windows 95, Windows NT, the Amiga operating system
and UNIX use preemptive multitasking
Cooperative
9 Each program can control the CPU for as long as it needs it.
9 If a program is not using the CPU, however, it can allow
another program to use it temporarily.
9 MS-Windows 3.x and the MultiFinder
(for Macintosh computers) use cooperative multitasking)
SINGLE USER OPERATING SYSTEM
These Operating System allow execution of
only one task at a time E.g.: MS-DOS
NETWORK OPERATING SYSTEM
An Operating System that includes special functions for connecting computer & devices into a local network (LAN). Some Operating systems, such as UNIX &
Mac OS, have built-in networking functions.
The term network operating system, however, is generally reserved for S/w that enhances a basic operating system by adding networking features. Example: some popular for DOS & Windows systems include: Novell Netware,
Airsoft's, LANtastic, MS-LAN Manager and
Windows NT.