Operating System and Data Communication

Operating system                  

            Operating system is a computer program that prepares the computer to be used by human user. It managed the computer hardware, central processing unit, memory, drivers, printers, etc. it also runs application software.

            Operating system programs reside in the main memory of the computer and control all operations of the computer. Commonly used operating systems are Unix, Mac OS, MS-DOS, OS/2 and Windows.

            A set of program running in the background on a computer system and providing an environment in which other program can be executed and the computer system can be used efficiently. It manages the software and resources of the system. These resources may include the process, m4emory, storage devices, input/output devices and many more. It provides stable and efficient way to use the hardware without having to know all detail of the hardware. We devide operating system into two categories depending upon their user interface.

            a. GUI (Graphical User Interface) Operating system.

            b. Command Line Operating System.

            A GUI operating system provides the user a graphical user interface to communicate with the computer. It provide graphical object such as icons, menus, windows, buttons and many more pointing and touchable controls to the user to perform

Kernel

Kernel is the main file, that is used to manage all the process management tasks by the operating system.

Stack

Stack is data structure. Operating System maintains a stack to manage the information required for process execution block (PCB), process scheduling, memory management and many more.

Queue

Queue is also a data structure. Queue is used to manage the execution of the programs and manage all the instructions on priority and sequential basis

SPOOL

Spooling in a process and an abbreviation of simultaneous peripheral operation online. In case situation, a device like printer in not available or on, installed, plugged in and some requests are being sent for printing. As soon as the printer is available, all printing jobs will be executed.

DOS

DOS is a command line interface, mostly used for managing of disk operations in past decades.

Device Drivers

Device drivers are the software provided with the devices which are newly installed with computer. These types of software are provided by the manufacturer of these devices. The program that contains specific instructions to operate and control a device attached to the computer is called device drivers. The operating systems usually have built in device drivers for most devices available in the market. Manufactures of devices also provide device drivers for the devices on a floppy disk or on a CD-Rom along with the devices. When the device is connected to the computer, the operating system asks for the device driver of the device. The device driver is copied from the floppy disk or CD-Rom to the operating system on the hard disk of the computer. This process is called installation of the device.

Firmware

On the basis of their native form, the computer software is divided into two types. Firmware and computer software. The instructions that are stored permanently in the computer ROM are called software.

Data communications

            Communication means the exchange of information or messages. The process of transferring data from one location to another is called data communication. In this process, data is transmitted electronically from one location to another by using standard methods.

            Today computer networks are commonly used for data communication. For this purpose, we use cables, tables, telephone lines, computers, and wireless devices that are linked in a network.

Components of Data Communication

Message

The message is the information or data that is to be communicated. It may be in the form of text, numbers, pictures, sounds, videos, videos or any combination of these.

Sender

A device that is used for sending messages (or data) is called sender.  It is also called transmitter or source. A sender may be computer, workstation, telephone, video camera and so on. Usually, a computer is used as sender in data communication system.

Receiver

A device that is used for receiving messages is called receiver. It may be a computer, a workstation, a telephone set, a television set, a printer, a fax machine and so on.

Medium

The path through which data is transmitted (sent) from one location to another is called transmission medium. It is also called communication channel. It may be a wire, or fiber optic cable, or telephone line etc. it the sender and receiver are within a building, a wire is used as the medium. It they are located at different locations, and then a medium may be telephone line, fiber optics cable, or telephone line etc. If the sender and receiver are within a building, a wire is used as the medium. If they are located at different locations, then a medium may be telephone line, fiber optics, microwave or satellite system.

Encoder

The encoder is an electronic device. It converts digital signals into a form, which can be transmitted through transmission medium.

Decoder

The decoder is an electronic device. It converts signals form encoded from into digital forms that are understandable for receiver.

Signals

            The data is transmitted from one place to another in the form of electromagnetic or light waves through communication medium. The electromagnetic or light waves representing data are called signals.

1.                  Analog Signals.

2.                  Digital Signals.

Analog Signals

The analog signals are continuous electronic signals in the form of wave. This wave is called carrier wave. The light waves, sound waves or radio waves are examples of analog signals. The data through telephone line is communicated in the form of analog signals. The data through telephone line is communicated in the form of analog signals. The analog signal has two characteristics. These are:

Frequency

      The number of times a wave repeats during a specific time interval is called frequency. It is measure in hertz (Hz).

Amplitude

      The height of a wave within a given period is called amplitude.

 

Digital Signals

A digital signal is a sequence of voltage represented in binary for. Actually, digital signals are on-off electrical pulses in discontinuous form (or in discrete form). Most of the computer are digital. Data is represented inside these computers in the form of binary numbers. It means that computers accept and process data in the form of digital signals.

                                            

Network

                  Sharing of data and resources in a secure and reliable way is called a network. A way of connecting computer tighter so that they can communicate share information and other resources with each other is call4ed computer network. Computer network is also called the information network.

 Uses of Network

a.       It allows the multiple users to access and share program and information at the same time.

b.            It allows multiple users to share peripheral devices, such as printers and hard disks.

c.                  It allow to send e-mails along with files.

d.            It allows the users to communicate via teleconferencing and video conferencing.

 

Basically network is classified into two categories.

Server Based	Peer to Peer
Centralized	Decentralized
Domain Based	Work Group

 

Work Group/Peer to peer/ decentralized

In this type of network, all the computers are of same type. They are doing their jobs in stand alone environment. There is no any kind of special computer for special purposes. All the computers are interconnected to share only limited files and resources. 

Server Based/Centralized/Domain Based/ Client Server

These types of networks are in such an architecture that is more secure, reliable, very minimum trouble arising ratio. Trouble shooting is easy as compared with decentralized environment. Securities and accessing of resources are more efficient and powerful.

All the resources are in centralized environments for example printers (for printing documents), scanners (for scanning documents and pictures, images), internet (net browsing, searching, viewing your email massages, sending emails), availability of space on hard disk for saving documents, accessing documents from the main computer (server)

Data entry from applications/software/programs (front ends) for accomplishing different record keeping procedures of Sale Invoices, Inventory Control Systems, Sale Tax Information System, Stock & wastage management systems, Accounting Systems to record all the transactions related with buying & selling, expenses, bank payment & receiving information, Accounting activities in banks by using client server architecture.

All the resources are equally distributed to all clients/terminal/end users computer to get the benefits of resources according to the user rights given by the network administrator. There are examples for some servers/special heavy duty computers are:-

 

a.                   Print server                  

b.                  Mail Server

c.                   FTP Server (File Transfer Protocol)

d.                  File Server (for document saving)

e.                   DNS Server

f.                    ADS Server

g.                   DHCP Server