BBA-I: Computer Applications for Business: Computer Networking

What is a Computer Network?

A computer network is a system in which multiple computers are connected to each other to share information and resources.

A computer network is a set of computers connected together for the purpose of sharing resources. The most common resource shared today is connection to the Internet. Other shared resources can include a printer or a file server. The Internet itself can be considered as a computer network.

A computer network is a set of connected computers. Computers on a network are called nodes. The connection between computers can be done via cabling, most commonly the Ethernet cable, or wireless through radio waves. Connected computers can share resources, like access to the Internet, printers, file servers, and others. A network is a multipurpose connection, which allows a single computer to do more.

Fig: A Computer Network

Characteristics of a computer network

·        Share Resources from one computer to another

·        Create files and store them in one computer, access those files from the other computer(s) connected over the network

·        Connect a printer, scanner, or a fax machine to one computer within the network and let other computers of the network use the machines available over network.

Following is the list of hardware's required to setup a computer network/Components/Tools for Networking:-

• Network Cables
• Distributors
• Routers
• Internal Network Cards
• External Network Cards

Network Cables

Network cables are used to connect computers. The most commonly used cable is Category 5 cable RJ-45.

Distributors

A computer can be connected to another one via a serial port but if we need to connect many computers to produce a network, this serial connection will not work. The solution is to use a central body to which other computers, printers, scanners etc. can be connected and then this body will manage or distribute network traffic.

Router

A router is a type of device which acts as the central point among computers and other devices that are part of a network. A router is equipped with holes called ports and computers and other devices are connected to a router using network cables. Now-a-days router comes in wireless modes using which computers can be connected without any physical cable.

Network Card

Network card is a necessary component of a computer without which a computer cannot be connected over a network. It is also known as network adapter or Network Interface Card (NIC). Most branded computers have network card pre-installed. Network cards are of two types : Internal and External Network Cards.

INTERNAL NETWORK CARDS

Motherboard has a slot for internal network card where it is to be inserted. Internal network cards are of two types in which first type uses Peripheral Component Interconnect (PCI) connection while the second type uses Industry Standard Architecture (ISA). Network cables are required to provide network access.

EXTERNAL NETWORK CARDS

External network cards come in two variants : Wireless and USB based. Wireless network card need to be inserted into the motherboard but no network cable is required to connect to network.

BBA-I- Computer Applications for Business: LINUX Operating System

Operating System - Linux

Linux is one of popular version of UNIX operating System. It is open source as its source code is freely available. It is free to use. Linux was designed considering UNIX compatibility. Its functionality list is quite similar to that of UNIX.

Following are some of the important features of Linux Operating System.

1. ·        Portable − Portability means software can works on different types of hardware in same way. Linux kernel and application programs support their installation on any kind of hardware platform.
2. ·        Open Source − Linux source code is freely available and it is community based development project. Multiple teams work in collaboration to enhance the capability of Linux operating system and it is continuously evolving.
3. ·        Multi-User − Linux is a multiuser system means multiple users can access system resources like memory/ ram/ application programs at same time.
4. ·    Multiprogramming − Linux is a multiprogramming system means multiple applications can run at same time.
5. ·        Hierarchical File System − Linux provides a standard file structure in which system files/ user files are arranged.
6. ·        Shell − Linux provides a special interpreter program which can be used to execute commands of the operating system. It can be used to do various types of operations, call application programs. etc.'
7.     Security − Linux provides user security using authentication features like password protection/ controlled access to specific files/ encryption of data.

Architecture

The following illustration shows the architecture of a Linux system −

The architecture of a Linux System consists of the following layers −

• ·        Hardware layer − Hardware consists of all peripheral devices (RAM/ HDD/ CPU etc).
• ·     Kernel − It is the core component of Operating System, interacts directly with hardware, provides low level services to upper layer components.
• ·        Shell − An interface to kernel, hiding complexity of kernel's functions from users. The shell takes commands from the user and executes kernel's functions.
• ·        Utilities − Utility programs that provide the user most of the functionalities of an operating systems.

Advantages of LINUX Operating System:

1.      Cost – The most obvious advantage of using Linux is the fact that it is free to obtain as it is an open and free software.

2.      Security – In line with the costs, the security aspect of Linux is much stronger, powerful and reliable.

3.      Choice (Freedom) – The power of choice is a great Linux advantage. With Linux, you have the power to control just about every aspect of the operating system.

4.      Software – There are so many software choices when it comes to doing any specific task. Regular users and programmers contribute applications all the time. In addition, software on Linux tends to be packed with more features and greater usability than software on Windows. Best of all, the vast majority of Linux software is free and open source.

5.      Hardware – Linux is perfect for those old computers with barely any processing power or memory.

Disadvantages of Linux Operating System:

1.    Understanding – Becoming familiar with the Linux operating system requires patience as well as a strong learning curve.

2.    Compatibility – Because of its free nature, Linux is sometimes behind the curve when it comes to brand new hardware compatibility.

BBA-I_Computer Applications for Business: UNIX Operating System

What is UNIX?

The UNIX operating system is a set of programs that act as a link between the computer and the user.

The computer programs that allocate the system resources and coordinate all the details of the computer's internals is called the operating system or kernel.

Users communicate with the kernel through a program known as the shell. The shell is a command line interpreter; it translates commands entered by the user and converts them into a language that is understood by the kernel.

Features of UNIX

·         Multiuser Capability

·         Multitasking Capability

·         Communication

·         Security

·         Portability

MULTI USER CAPABILITY:

UNIX Operating System supports many users to use the resources from different computers connected to it at the same time. There need not be operating system installed on all of them. A single computer with UNIX operating system can help in running all of them at the same time.

MULTI TASKING CAPABILITY:

It is capable of carrying out more than one job at the same time. It allows user to type in a program in its editor while  it simultaneously   executes  some other commands  like  sort,  copy  a huge file.

The later job is performed in the background while in the foreground uses the editor or takes a directory listing or anything else.

This is managed by dividing  the  CPU  time  intelligently between all process being carried out .Depending on the  priority of the task, the OS    approximately  allots   small time slots  (of  the order of milliseconds or  microseconds)  to  each foreground and background task.

COMMUNICATION:

The communication may be within the network of a single main  computer or between two or more such computer networks. The users can easily  exchange  mail,  data  programs    through   such networks. Distance  posses  no barrier to passing  information  or messages to and fro.

SECURITY:

Unix has 3  inbuilt features for protecting data:-

i) Assign passwords and login name to users area.

ii) Provide read, write and execute permission to each file.

iii)Encrypt files into an unreadable format, and decrypting the file is also possible.

PORTABILITY:

Unix is a highly portable OS. It can be ported to a variety of hardware platforms. It is the only system which has been ported across various hardware platforms of major vendors such as IBM, DEC, HP and SUN. Most OSs are written for one specific machine or platform only.

Advantages of Unix

-  Unix is more flexible and can be installed on many different types of machines, including main-frame computers, supercomputers and micro-computers.

- Unix is more stable and does not go down as often as Windows does, therefore requires less administration and maintenance.

- Unix has greater built-in security and permissions features than Windows.

- Unix possesses much greater processing power than Windows.

- Unix is the leader in serving the Web. About 90% of the Internet relies on Unix operating systems running Apache, the world's most widely used Web server.

- Software upgrades from Microsoft often require the user to purchase new or more hardware or prerequisite software. That is not the case with Unix.

Disadvantages of Unix:

Interface

·         The traditional interface for the Unix operating system is command line based, and this command line shell interface may be hostile to the casual user. Unix was developed for use by programmers and serious computer users rather than casual users. A graphical user interface (GUI) is also available, but the traditional Unix interface is command line only.

Special Commands

·         Commands required by the command line interface often make use of cryptic naming schemes, and do not give much information to notify a user of what they are doing. Many commands in the Unix interface require the use of special characters. Small, normally insignificant typos can have much greater effects and unexpected results on Unix machines.

Not User-Friendly:

·         Not as user-friendly or easy to learn for the average person as windows is.

BBA-I CAB: MS-DOS & Windows Operating system & Features

Source: Computer Applications for Business Thakur Publications

BBA-I_CAB_Operating System

An Operating System (OS) is an interface between a computer user and computer hardware. An operating system is a software which performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers.

An operating system or OS is a software program that enables the computer hardware to communicate and operate with the computer software. Without a computer operating system, a computer and software programs would be useless. The picture is an example of Microsoft Windows XP, a popular operating system and what the box may look like if you were to visit a local retail store to purchase it.

When computers were first introduced, the user interacted with them using a command line interface, which required commands. Today, almost every computer is using a Graphical User Interface (GUI) operating system that is much easier to use and operate.

Some popular Operating Systems include MS-DOS, Windows, UNIX, Linux.

Fig: Operating System

Following are some of important functions of an operating System.

• Memory Management
• Processor Management
• Device Management
• File Management
• Security
• Control over system performance
• Job accounting
• Error detecting aids
• Coordination between other software and users

Memory Management

Memory management refers to management of Primary Memory or Main Memory. Main memory is a large array of words or bytes where each word or byte has its own address.

Main memory provides a fast storage that can be accessed directly by the CPU. For a program to be executed, it must in the main memory. An Operating System does the following activities for memory management:

1. ·        Keeps tracks of primary memory, i.e., what part of it are in use by whom, what part is not in use?
2. ·        In multiprogramming, the OS decides which process will get memory when and how much.
3. ·        Allocates the memory when a process requests it to do so.
4. ·        De-allocates the memory when a process no longer needs it or has been terminated.

 

 Processor Management

In multi programming environment, the OS decides which process gets the processor when and for how much time. This function is called process scheduling. An Operating System does the following activities for processor management −

1. ·        Keeps tracks of processor and status of process. The program responsible for this task is known as traffic controller.
2. ·        Allocates the processor (CPU) to a process.
3. ·        De-allocates processor when a process is no longer required.

Device Management

An Operating System manages device communication via their respective drivers. It does the following activities for device management −

1. ·        Keeps tracks of all devices. Program responsible for this task is known as the I/O controller.
2. ·        Decides which process gets the device when and for how much time.
3. ·        Allocates the device in the efficient way.
4. ·        De-allocates devices.

File Management

A file system is normally organized into directories for easy navigation and usage. These directories may contain files and other directions.

An Operating System does the following activities for file management −

1. ·        Keeps track of information, location, uses, status etc. The collective facilities are often known as file system.
2. ·        Decides who gets the resources.
3. ·        Allocates the resources.
4. ·        De-allocates the resources.

Other Important Activities

Following are some of the important activities that an Operating System performs −

1. ·        Security − By means of password and similar other techniques, it prevents unauthorized access to programs and data.
2. ·        Control over system performance − Recording delays between request for a service and response from the system.
3. ·        Job accounting − Keeping track of time and resources used by various jobs and users.
4. ·        Error detecting aids − Production of dumps, traces, error messages, and other debugging and error detecting aids.
5. ·        Coordination between other software and users − Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.

BBA-I; CAB: Working of a Computer

A computer functions in the following manner:

• The computer accepts input. Computer input is whatever is entered or fed into a computer system. Input can be supplied by a person (such as by using a keyboard) or by another computer or device (such as a diskette or CD-ROM). Some examples of input include the words and symbols in a document, numbers for a calculation, instructions for completing a process, pictures, and so on.

• The computer performs useful operations, manipulating the data in many ways. This manipulation is called processing. Examples of processing include performing calculations, sorting lists of words or numbers, modifying documents and pictures according to user instructions, and drawing graphs. A computer processes data in the CPU.

• The computer stores data. A computer must store data so that it is available for processing. Most computers have more than one location for storing data (the hard drive or C:\, and the floppy drive or A:\). The place where the computer stores the data depends on how the data is being used. The computer puts the data in one place while it is waiting to be processed and another place when it is not needed for immediate processing. The storage of data in the computer is called online storage’ while the storage of data on computer tapes, diskettes or CD-ROMs is called ‘offline storage’.

• The computer produces output. Computer output is information that has been produced by a computer. Some examples of computer output include reports, documents, music, graphs, and pictures. Output can be in several different formats, such as paper, diskette, or on screen.

BBA-I: CAB- Types/Classification Of Software

Fig: Classification of Software

 Software is a set of programs, which is designed to perform a well-defined function. 

A program is a sequence of instructions written to solve a particular problem. 

There are two types of software

  System Software

  Application Software

Software System:

The system software is collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software are generally prepared by computer manufactures. These software products comprise of programs written in low-level languages which interact with the hardware at a very basic level. System software serves as the interface between hardware and the end users.

Some examples of system software are Operating System, Compilers, Interpreter, Assemblers etc.

Operating System:The operating system is the software that allows you to operate the hardware. The programs that we want to execute, the applications that we want to use all require a platform on which to execute. That platform is provided by the operating system.

One role of the operating system is to provide a virtual machine. This refers to the way that, by clicking on icons and menus, or by typing in commands at a prompt, we get to interact with the computer hardware without having to understand its complexity. By hiding the true complexity of the system from the user, the operating system makes it easier for ordinary people to make computers perform useful tasks.

Language Translators:

Whatever language or type of language we use to write our programs, they need to be in machine code in order to be executed by the computer. There are 3 main categories of translator used,

Assembler

An assembler is a program that translates the mnemonic codes used in assembly language into the bit patterns that represent machine operations. Assembly language has a one-to-one equivalence with machine code, each assembly statement can be converted into a single machine operation.

Compiler

A compiler turns the source code that you write in a high-level language into object code (machine code) that can be executed by the computer.

The compiler is a more complex beast than the assembler. It may require several machine operations to represent a single high-level language statement. As a result, compiling may well be a lengthy process with very large programs.

Interpreter

Interpreters translate the source code at run-time. The interpreter translates statements one-at-a-time as the program is executed.

Interpreters are often used to execute high-level language programs whilst they are being developed since this can be quicker than compiling the entire program. The program would be compiled when it is complete and ready to be released.

Some programming languages make use of both compilers and interpreters. If you were to write a Java program in a text editor, when you came to compile it with the Java compiler, you would actually be creating something called bytecode. Bytecode can be thought of as an intermediate stage between source code and object code. When a computer executes a Java program, library programs on that machine interpret the bytecode. This allows Java to be platform-independent - a user needs the correct run-time libraries for Java on their machine in order to execute the programs.

Application Software:

Application software tends be used for the tasks that have some relationship to the world outside of the computer. For example, you might use a word processor to write a letter or an essay. Although you use the computer to perform the task, the task itself might reasonably be considered to be a non-computer task.

General-Purpose Software

Software is general-purpose if it can be used for lots of different tasks. You can use a word processor to write letters, memos, essays, instructions, notes, faxes, invoices and lots more.

These days we tend to use integrate suites of office software where a range of general-purpose software is provided, usually with the facility to combine elements from each application in a single file.

Special-Purpose Software

This software performs a single specific task. This task might be complex like payroll calculation, stock control etc. but will be based on a single task.

As with many abstract concepts, you can stretch these definitions until they blur a little. These days, web browsers can contain a lot of features. They are still primarily focused on a single task, rendering web pages and so the web browser is special-purpose. Being able to access an application using a browser does not change the main purpose of the browser software itself.

Source: http://www.multiwingspan.co.uk/