Aral-aral pag may time ;) (F.Y.I) For Your Information COMPUTER SOFTWARE • The first application of computers in business were in the early 1950s. Software was less important (and less costly) in computer system then, because early hardware was literally hardwired by hand for each application. Today, software comprises a much larger percentage of the cost of modern computer systems than it did in the 1950s. There are several reasons for this trend, First, the price of hardware dramatically decreased, while the performance of hardware has exponentially increased. Second, building applications – a process called SOFTWARE DEVELOPMENT – is slow, complex, and error-pane. Software is, therefore, expensive and getting more so as its complexity grows. Finally, salaries for software developers are steadily increasing because there is an increased demand for their skills. • Software is a set of programs, which are designed to perform a well-defined function. A program is a sequence of instructions written to solve a particular problem. COMPUTER PROGRAMS – software consists of it, which are sequences of instructions for the computer. PROGRAMMING – is the process of writing or coding programs. PROGRAMMERS – are the individuals who perform the task of writing programs. DOCUMENTATIONS – is a written description of the functions of the program. It helps the user operate the computer system and helps other programmers understand what the program does and how it accomplishes its purpose. Without it, if a key programmer or user leaves, the knowledge of how to use the program or how it is designed may be lost. TWO TYPES OF SOFTWARE: 1. System Software 2. Application Software I. System Software – is a set of instructions that serves primarily as an intermediary between computer hardware and application programs, and may also be directly manipulated by knowledgeable user. • It provides important self-regulatory functions for computer systems, such as loading itself when the computer is first turned on, managing hardware resources such as secondary storage for all applications, and providing commonly used sets of instructions for all applications to use. • System Programming is either the creation or maintenance of system software. • System software can be grouped into two major functional categories: System Control Programs and System Support Programs. Features of System Software are the following: • Close to system. • Fast in speed. • Difficult to design. • Difficult to understand. • Less interactive. • Smaller in size. • Difficult to manipulate. • Generally written in low-level language. a) SYSTEM CONTROL PROGRAMS – control the use of the hardware, software, and data resources of a computer. o OPERATING SYSTEM – is the main system control program. It supervises the overall operation of the computer, including monitoring the computer’s status and scheduling operations, which include the input and output processes. It allocates CPU time and main memory to programs running on the computer, and it also provides an interface between the user and the hardware. Specifically, it provides services that include Process Management, Virtual Memory, File Management, Security, Fault Tolerance and the User Interface. Process Management – means managing the program or programs (also called jobs) running on the processor at a given time. In simplest case (a desktop operating system), the OS loads a program into main memory and executes it. The program utilizes the computer’s resources until it relinquishes control. Some OS offer more sophisticated forms of process management, such as: 1. Multitasking – (or multiprogramming) the first program is executed until an interruption occurs, such as a request for input. While the input request is handled, the execution of a second program begins. Because switching among these programs occurs so rapidly, they appear to be executing at the same time. However, because there is only one processor, only one program is actually in execution mode at any one time. 2. Multithreading – is a form of multitasking that focuses on running multiple tasks within a single application simultaneously. For ex: a word processor application may edit one document while another document is being spell-checked. 3. Time-sharing – is an extension of multiprogramming. In this mode, a number of users operate online with the same CPU, but each uses a different input/output terminal. The programs of these users are placed into partitions in primary storage. Executions of these programs rotate among all users, occurring so rapidly that it appears to each user as though he or she were the only one using the computer. 4. Multiprocessing – occurs when a computer system with two or more processors can run more than one program. It uses simultaneous processing with multiple CPU’s whereas multiprogramming involves concurrent processing with one CPU. Virtual Memory – simulates more main memory than actually exists in the computer system. It allows a program to behave as if it had access to the full storage capacity of a computer, rather than just access to the amount of primary storage installed on the computer. It divides an application program or module into fixed-length portions called PAGES. The system executes some pages of instructions while pulling others from secondary storage. In effect, primary storage is extended into a secondary storage device, allowing users to write programs as if primary storage were larger than it actually is. This enlarged capability boosts the speed of the computer and allows it to efficiently run programs with very large number of instructions. The OS is responsible for FILE MANAGEMENT and SECURITY, managing the arrangement of, and access to, files held in secondary storage. The OS creates and manages a directory structure that allows files to be created and retrieved by name, and it also may control access to those files based on permissions and ample, it must typically provide protected memory and maintain access control on files in the file system. The OS also must keep track of users and their authority level as well as audit changes to security permissions. Fault Tolerance – is the ability of a system to produce correct results and to continue to operate even in the presence of faults or errors. It can involve error-correcting memory, redundant computer components, and related software that protect the system from hardware, operating system, or user errors. Although OS perform some of their functions automatically, for certain tasks the user interacts directly with the computer through the systems software. The ease or difficulty of such interaction is to a large extent determined by the Interface Design. Older text-based interfaces like DOS (Disk Operating System) required typing in cryptic commands. In an effort to make computers more user-friendly, the graphical user interface was developed. Graphical User Interface (GUI) – allows user to have direct control of visible objects (such as icons) and actions that replace complex command syntax. The GUI was developed by researchers at Xerox PARC (Palo Alto Research Center), and then popularized by the Apple Macintosh computer. Microsoft soon introduced its GUI-based Windows OS for IBM-style PC’s. The next generation of GUI technology will incorporate features such as virtual reality, head-mounted displays, sound and speech, pen and gesture recognition, animation, multimedia, artificial intelligence and cellular/wireless communication capabilities. The next step in the evolution of GUI’s is social interfaces. A SOCIAL INTERFACE is a user interface that guides the user through computer application by using cartoonlike characters, graphics, animation and voice commences. The cartoonlike characters can be cast as puppets, narrators, guides, inhabitants, avatars (computer-generated humanlike figures), or hosts. COMMON OPERATING SYSTEM TASKS • Monitoring performance • Correcting errors • Providing and maintaining the user interface • Starting (“booting”) the computer • Reading programs into memory • Managing memory allocation to those programs • Placing files and programs in secondary storage • Creating and maintaining directories • Formatting diskettes • Controlling the computer monitor • Sending jobs to the printer • Maintaining security and limiting access • Locating files • Detecting viruses • Compressing data Characteristics of Operating System • Memory Management -- It keeps track of primary memory, i.e., what parts of it are in use by whom, what parts are not in use, etc. Allocates the memory when the process or program requests it. • Processor Management -- Allocates the processor (CPU) to a process. Deallocate processor when processor is no longer required. • Device Management -- Keeps tracks of all devices. This is also called I/O controller. Decides which process gets the device when and for how much time. • File Management -- Allocates the resources. Deallocates the resource. Decides who gets the resources. • Security -- By means of passwords & similar other techniques, preventing unauthorized access to programs & data. • Job accounting -- Keeping track of time & resources used by various jobs and/or users. • Control over system performance -- Recording delays between requests for a service & from the system. • Interaction with the operators -- The interaction may take place via the console of the computer in the form of instructions. Operating System acknowledges the same, do the corresponding action and inform the operation by a display screen. • Error-detecting aids -- Production of dumps, traces, error messages and other debugging and error-detecting methods. • Coordination between other software and users -- Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems. TYPES OF OPERATING SYSTEM Operating Environments – which add features that enable system developers to create applications without directly accessing the OS, function only with an OS. That is, operating environments are not OS, but work only with an OS. • Operating Systems (Oss) can be categorized by the number of users they support as well as by their level of sophistication. o Mobile Operating System – are designed to support a single person using a mobile, handheld device, or information appliance. Embedded Linux – is a compact form of Linux used in mobile devices. Both IBM and Motorola are developing Embedded Linux for mobile devices. Windows CE – a 32-bit OS, is Microsoft’s information appliance OS. It includes scaled-down version (known as Pocket Versions) of Microsoft Word, Excel, Powerpoint and Internet Explorer. Pocket PC – is a version of Windows CE 3.0 specifically designed for personal digital assistants and handheld computers. Windows Embedded NT 4.0 – a 32-bit OS, is aimed at embedded devices that require more OS capabilities and flexibility than Windows CE can offer. The Palm OS – was developed by Palm for its PalmPilot handheld, pen-input PDAs. Palm OS includes a graphical user interface, and users must learn a stylized alphabet, called Grafiti, to make the device receive handwritten input. o Desktop and Netbook Computer Operating System – are designed to support a single user or a small workgroup of users. The MS-DOS (Microsoft Disk Operating System) – was one of the original OS for the IBM PC and its clones. This 16-bit operating system, with its text-based interface, has now been almost totally replaced by GUI OS such as Windows 2000 and Windows XP. Windows 1.0 through Windows 3.1 (successive versions) – were not OS but were Operating Environments that provided the GUI that operated with, and extended the capabilities of MS-DOS. Windows 95 – is released in 1995, was the first of a series of products in the Windows OS that provided a streamlined GUI by using icon to provide instant access to common task. It is a 32-bit OS that features multitasking, multithreading, networking and Internet integration capabilities, including the ability to integrate fax, e-mail, and scheduling programs. It also offers plug-and-play capabilities that can automate the installation of new hardware by enabling the OS to recognize new hardware and install the necessary software (called Device Drivers) automatically. Windows 98 – was not a major upgrade to Win 95, but did offer minor refinements, bug fixes, and enhancement to Win 95. Windows Millennium Edition (Windows ME) – is a major update to Win 95, offering improvements for home computing in the areas of PC reliability, digital media, home networking and the online experience. Windows NT – is an OS for high-end desktops, workstations and servers. It provides the same GUI as Win 95 and 98, and has more powerful multitasking, multiprocessing and memory-management capabilities. It is also designed for easy and reliable connection with networks and other computing machinery and is proving popular in networked systems in business organizations. Windows 2000 – is a renamed version of Windows NT 5.0. This OS has added security features, will run on multiple-processor computers, and offers added Internet and Intranet functionality. Windows XP – is the first upgrade to Windows 2000 and has three versions: a 32-bit consumer version, a 32-bit business version and a 64-bit business version. It is the first version of Windows to support Microsoft’s NET platform. Blackcomb – following Win XP, Microsoft released its first fully NET-enabled Win OS, code-named Blackcomb. It will feature natural interfaces, including speech recognition and handwriting support. UNIX – provides many sophisticated desktop features, including multiprocessing and multitasking. It is valuable to business organizations because it can be used on many different sizes of computers (or different platforms), can support many different hardware devices (e.g. printers, plotters, etc) and has numerous applications written to run on it. LINUX – is a powerful version of the UNIX OS that is completely free of charge. It offers multitasking virtual memory management, and TCP/IP networking. It is originally written by Linus Torvalds at the University of Helsinki in Finland in 1991. The Macintosh Operating System X (ten) (Mac OS X) – for Apple Macintosh microcomputers, is a 32-bit OS that supports Internet integration, virtual memory management, and AppleTalk networking. Mac OS X features a new Aqua user interface, advanced graphics, virtual memory management, and multitasking. IBM’s OS/2 – is a 32-bit OS that supports multitasking, accommodates larger application, allows applications to be run simultaneously, and supports networked multimedia and pen-computing applications. Sun’s Java OS (Java OS) – executes programs written in the Java language without the need for a traditional OS. It is designed for Internet and intranet applications and embedded devices. It is designed for handheld products and thin-client computing. Departmental Server Operating System – it include UNIX, Linux, Windows 2000, Windows XP, and Novell NetWare. Although some of these are also desktop operating systems, all can serve as departmental server operating system because of their strong scalability, reliability, backup, security, fault tolerance, multitasking, multiprocessing, TCP/IP networking (Internet integration), network management, and directory services. Enterprise Server Operating System – (e.g., IBM’s OS/390, VM, VSE, and OS/400) generally run on mainframes and midrange systems. Enterprise operating systems offer superior manageability, security, stability, and support for online applications, secure electronic commerce, multiple concurrent users, large (terabyte) databases, and millions of transaction per day. Supercomputer Operating System – it target the supercomputer hardware market. Examples of this system include the Cray Unicos and IBM’s AIX (both types of UNIX). These two operating system manage highly parallel multiprocessor and multiuser environments. b) SYSTEM SUPPORT PROGRAMS – supports the operations, management, and users of a computer system by providing a variety of support services. Examples of system support programs are the following: System Utilities – are programs that have been written to accomplish common tasks such as sorting records, checking the integrity of diskettes (ex. Amount of storage available and existence of any damage), and creating directories and subdirectories. They also restore accidentally erased files, locate files within the directory structure, manage memory usage and redirect output. System Performance Monitors – are programs that monitor the processing of jobs on a computer system. They monitor computer system performance and produce reports containing detailed statistics relating to the use of system resources, such as processor time, memory space, input/output devices, and system and application programs. These reports are used to plan and control the efficient use of computer system resources and to help troubleshoot the system in case of problems. System Security Monitors – are programs that monitor the use of a computer system to protect it and its resources from unauthorized use, fraud or destruction. Such programs provide the computer security needed to allow only authorized users access to the system. It control the use of the hardware, software, and data resources of a computer system. II. APPLICATION SOFTWARE – consists of instructions that direct a computer system to perform specific information processing activities and that provide functionality for users. Because there are so many different uses for computers, there are a correspondingly large number of different application software programs available. Features of Application Software are the following: • It is close to user. • It is easy to design. • More interactive. • Slow in speed. • Generally written in high-level language. • Easy to understand. • Easy to manipulate and use. • Bigger in size and requires large storage space. TYPES OF APPLICATION SOFTWARE • Application software includes proprietary application software and off-the-shelf application software. o Proprietary Application Software – addresses a specific or unique business need for a company. This type of software may be developed in-house by the organization’s information systems personnel or it may be commissioned from a software vendor. Such specific software programs developed for a particular company by a vendor are called Contract Software. o Personal / Off-the-shelf Application Software – can be purchased, leased, or rented from a vendor that develops programs and sells them to many organizations. It may be a standard package or it may be customizable. Special Purpose Programs or “Packages” can be tailored for a specific purpose, such as inventory control or payroll. The word PACKAGE is a commonly used term for a computer program (or group of programs) that has been developed by a vendor and is available for purchase in a prepackaged form. TYPES OF PERSONAL APPLICATION SOFTWARE • It consists of nine widely used packages: spreadsheet, data management, word processing, desktop publishing, graphics, multimedia, communications, speech-recognition software, and groupware. It is designed to help individual users increase their productivity. 1. SPREADSHEETS – Computer spreadsheet software transforms a computer screen into a ledger sheet, or grid, of coded rows and columns. User can enter numeric or textual data into each grid location, called a CELL. In addition, a formula can be entered into a cell to obtain a calculated answer displayed in that cell’s location. Computer spreadsheet packages can be used for financial information, such as income statements or cash flow analysis. They are also used for forecasting sales, analyzing insurance programs, summarizing income tax data, and analyzing investments. (MS Excel and Lotus 1-2-3, offer data management and graphical capabilities – Integrated Packages). 2. DATA MANAGEMENT – Data management supports the storage, retrieval, and manipulation of related data. There are two basic types of data management software: Simple Filing Programs – patterned after traditional, manual data-filing techniques, and Database Management Programs – that take advantage of a computer’s extremely fast and accurate ability to store and retrieve data in primary and secondary storage. (Microsoft’s Access) 3. WORD PROCESSING – Word processing software allows the user to manipulate text rather than just numbers. Modern word processors contain many productive writing and editing features. A typical word processing software package consists of an integrated set of programs including an editor program, a formatting program, a print program, a dictionary, a thesaurus, a grammar checker, a mailing list program, and integrated graphics, charting, and drawing programs. WYSIWYG (What You See Is What You Get, pronounced as “wiz-e-wig”) word processors have the added advantage of displaying the text material on the screen exactly – or almost exactly – as it will look on the final printed page (based on the type of printer connected to the computer). It enables users to be much more productive because the software makes it possible to create and modify the document electronically in memory. 4. DESKTOP PUBLISHING – represents a level of sophistication beyond regular word processing. In the past, newsletters, announcements, advertising copy and other specialized documents had to be laid out by hand and then typeset. It allows microcomputers to perform these tasks directly. Photographs, diagrams, and other images can be combined with text, including several different fonts, to produce a finished, camera-ready document. 5. GRAPHICS – graphic software allows the user to create, store, and display or print charts, graphs, maps, and drawings. Graphics software enables users to absorb more information more quickly and to spot relationships and trends in data more easily. There are three basic categories of graphics software packages: a. Presentation Graphic Software – allows users to create graphically rich presentations. Many packages have extensive libraries of clip art – pictures that can be electronically “clipped out” and “pasted” into the finished image. (MS PowerPoint) b. Analysis Graphics – applications additionally provide the ability to convert previously analyzed data – such as statistical data – into graphic formats like bar charts, line charts, pie charts, and scatter diagrams. Both presentation graphics and analysis graphics are useful in preparing graphic displays for business presentations, from sales results to marketing research data. c. Computer-Aided Design (CAD) Software – used for designing items for manufacturing, allows designers to design and “build” production prototypes in software, test them as a computer object under given parameters (sometimes called Computer-Aided Engineering, or CAE), compile parts and quantity lists, outline production and assembly procedures, and then transmit the final design directly to machines. 6. MULTIMEDIA – combines at least two media for input or output of data. These media include audio (sound), voice, animation, video, text, graphics, and images. Multimedia can also be thought of as the combination of spatial-based media (text and images) with time-based media (sound and video). 7. COMMUNICATIONS – computers are often interconnected in order to share or relate information. To exchange information, computers utilize communication software. This software allows computers, whether they are located close together or far apart, to exchange data over dedicated or public cables, telephone lines, satellite relay systems, or microwave circuits. 8. SPEECH-RECOGNITION SOFTWARE – Two categories of speech-recognition software are available today: Discrete Speech and Continuous Speech. a. Discrete Speech Recognition – can interpret only one word at a time, so users must place distinct pauses between words. This type of voice recognition can be used to control PC software (by using words such as “execute” or “print”). b. Continuous Speech Recognition – can interpret a continuing stream of words. The software must understand the context of a word very quickly. These requirements mean that continuous speech-recognition software must have a computer with significantly more speed and memory than discrete speech software. 9. GROUPWARE – is a class of software products that facilitates communication, coordination, and collaboration among people. Groupware is important because it allows workgroups – people who need to interact with one another within an organization – to communicate and share information, even when they are working together at a distance. It can provide many benefits to business, including more efficient and effective project management, location independence, increased communications capability, increased information availability, and improved workflow. (Microsoft’s Exchange, Netscape’s SuiteSpot Servers, Novell’s GroupWise, and Oracle’s InterOffice.) SOFTWARE SUITES – are collections of application software packages that integrate some or all of the nine functions of the packages described in this section. It can include word processors, spreadsheets, database management systems, graphics programs, communications tools, and other applications. Microsoft Office, Novell Perfect Office, and Lotus SmartSuite are widely used software suites for PCs. Each of these suites includes a spreadsheet program, word processor, database program, and graphics package with the ability to move documents, data, and diagrams among them. PROGRAMMING LANGUAGES – provide the basic building blocks for all systems and application software. It allows people to tell computers what to do and is the means by which software systems are developed. This section will describe the five generation of programming languages. GENERATIONS OF PROGRAMMING LANGUAGE • Languages are a means of communication. Normally people interact with each other through a language. On the same pattern, communication with computers is carried out through a language. This language is understood both by user and the machine. Just as every language like English, Hindi has its grammatical rules; every computer language is bound by rules known as SYNTAX of that language. The user is bound by that syntax while communicating with the computer system. I. LOW-LEVEL LANGUAGE - the term low level means closeness to the way in which machine understand. (Machine Language and Assembly Language) 1. MACHINE LANGUAGE – is the lowest level computer language, consisting of the internal representation of instructions and data. This machine code – the actual instructions understood and directly executable by the central processing unit – is composed of binary digits. It is the only programming language that the machine actually understands. Therefore, machine language is considered the First Generation Language. All other languages must be translated into machine language before the computer can run the instructions. Because a computer’s central processing unit is capable of executing only machine language programs, such programs are machine dependent (nonportable). That is, the machine language for one type of central processor may not run on other types. It is extremely difficult to understand and use by programmers. As a result, increasingly more user-friendly languages have been developed. (0-1 Long, difficult programming) 2. ASSEMBLY LANGUAGE – is the next level up from machine language. It is still considered a lower-level language but is more user-friendly because it represents machine language instructions and data locations in primary storage by using mnemonics, or memory aids, which people can more easily use. It is considered as the Second Generation Languages. Compared to machine language, assembly language eases the job of the programmer considerably. However, each statement in an assembly language must still be translated into a single statement in machine language, and assembly languages are still hardware dependent. Translating an assembly language program into machine language is accomplished by a systems software program called an Assembler. (Assemble repetitive instructions, shorter code) II. HIGH LEVEL LANGUAGE (Procedural Language, Non-Procedural Language, and Natural Programming Language) o You know that low level language requires extensive knowledge of the hardware since it is machine dependent. To overcome the limitation, high level language has been evolved which uses normal English like, easy to understand statements to solve any problem. Higher level languages are computer independent and programming becomes quite easy and simple. Various high level languages are given below: a. BASIC (Beginners All Purpose Symbolic Instruction Code): It is widely used, easy to learn general purpose language. Mainly used in microcomputers in earlier days b. COBOL (Common Business Oriented language): A standardized language used for commercial applications. c. FORTRAN (Formula Translation): Developed for solving mathematical and scientific problems. One of the most popular languages among scientific community. d. C: Structured Programming Language used for all purpose such as scientific application, commercial application, developing games etc. e. C++: Popular object oriented programming language, used for general purpose. 3. PROCEDURAL LANGUAGES – are the next step in the evolution of user-oriented programming languages. They are also called the Third Generation Languages, or 3GLs. Procedural languages are much closer to so-called natural language (the way we talk) and therefore are easier to write, read, and alter. Moreover, one statement in a procedural language is translated into a number of machine language instructions, thereby making programming more productive. In general, they are more like natural language than assembly languages are, and they use common words rather than abbreviated mnemonics. Because of this, they are considered the first level of Higher Level Languages. Procedural languages require the programmer to specify, step by step, exactly how the computer must accomplish a task. (Include commands, shorter code) o Language Translator – converts the high-level program, called Source Code, into machine language code, called Object Code. There are two types of language translators – Interpreters and Compilers. COMPILER – the translation of a high-level language program to object code is accomplished by a software program, which translates the entire program at once. INTERPRETER – is a compiler that translates and executes one source program statement at a time. Because this translation is done one statement at a time, interpreters tend to be simpler than compilers. This simplicity allows for more extensive debugging and diagnostic aids to be available on interpreters. 4. NONPROCEDURAL LANGUAGES – allows the user to specify the desired result without having to specify the detailed procedures needed for achieving the result. These languages are Fourth Generation Languages (4GLs). An advantage of nonprocedural languages is that they can be used by nontechnical users to carry out specific functional tasks. These languages greatly simplify and accelerate the programming process, as well as reduce the number of coding errors. They are common in database applications as query languages, report generators, and data-manipulation languages. They allow users and programmers to interrogate and access computer databases using statements that resemble natural language. (Application generators, commands specify result) 5. NATURAL PROGRAMMING LANGUAGES – are the next evolutionary step. They are sometimes known as Fifth Generation Languages or Intelligent Languages. Transistor programs to translate natural languages into a structured, machine-readable form are extremely complex and require a large amount of computer resources. Therefore, most of these languages are still experimental and have yet to be widely adopted by industry. DATA AND INFORMATION What is Data? • Data can be defined as a representation of facts, concepts or instructions in a formalized manner, which should be suitable for communication, interpretation or processing by human or electronic machine. • Data is represented with the help of characters like alphabets (A-Z, a-z), digits (0-9) or special characters (+,-,/,*,,=, etc.). .What is Information? • Information is organized or classified data so that it has some meaningful values to the receiver. • Information is the processed data on which decisions and actions are based. For the decision to be meaningful, the processed data must qualify the following characteristics: • Timely - Information should be available when required. • Accuracy - Information should be accurate. • Completeness - Information should be complete. Data Processing Cycle • Data processing is the re-structuring or re-ordering of data by people or machine to increase their usefulness & add values for particular purpose. • Data processing consists of basic steps input, processing and output. These three steps constitute the data processing cycle. • Input - In this step, the input data are prepared in some convenient form for processing. The form will depend on the processing machine. For example, when electronic computers are used, the input data could be recorded on any one of several types of input mediums, such as magnetic disks, tapes and so on. • Processing - In this step, input data are changed to produce data in a more useful form. For example, pay-checks may be calculated from the time cards or a summary of sales for the month may be calculated from the sales orders. • Output -Here, the results of the proceeding processing step are collected. The particular form of the output data depends on the use of the data. For example, output data may be pay-checks for employees. 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. Characteristics • 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 required to set up a computer network: • Network Cables • Distributors • Router • Internal Network Cards • External Network Cards Network Cables Network cables are used to connect computers. The most commonly used cable are Category 5 cable RJ-45. Distributors • Each and every 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. • Computers and other devices are connected to a router using network cables. • Nowadays, 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. • Also known as network adapter or Network Interface Card (NIC). • Most of 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: • First type uses Peripheral Component Interconnect (PCI) connection. • Second type uses Industry Standard Architecture (ISA). • Network cables are required to provide network access. External Network Cards • Comes in two flavors: Wireless and USB based. • Wireless network card needs to be inserted into the motherboard but no network cable is required to connect to network. • USB cards are easy to use and connect via USB port. • Computer automatically detects USB card and can install the drivers required to support the USB network card automatically. INTERNET & INTRANET Internet • Internet is a world-wide/global system of interconnected computer networks. • Internet uses the standard Internet Protocol (TCP/IP) • Every computer in internet is identified by a unique IP address. • IP Address is a unique set of numbers (such as 110.22.33.114) which identifies a computer location. • A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name. • For example, a DNS server will resolve a name tutorialspoint to a particular IP address to uniquely identify the computer on which this website is hosted. • Internet is accessible to every user all over the world. Intranet • Intranet is system in which multiple PCs are networked to be connected to each other. • PCs in intranet are not available to the world outside of the intranet. • Usually each company or organization has their own Intranet network and members/employees of that company can access the computers in their intranet. • Each computer in Intranet is also identified by a IP Address, which is unique among the computers in that Intranet. Similarities in Internet & Intranet • Intranet uses the internet protocols such as TCP/IP and FTP. • Intranet sites are accessible via web browser in similar way as websites in internet. But only members of Intranet network can access intranet hosted sites. • In Intranet, own instant messengers can be used as similar to yahoo messenger/gtalk over the internet. Differences in Internet & Intranet • Internet is general to PCs all over the world where Intranet is specific to few PCs. • Internet is wider access and provides a better access to websites to large population whereas Intranet is restricted. • Internet is not as safe as Intranet as Intranet can be safely privatized as per the need. HEALTH & SAFETY PRECAUTIONS IN USING COMPUTER • Make sure that cables are safely secured • Make sure that power points are not overloaded Also be aware of: • Repetitive Strain Injury (RSI) • Glare from screens • Bad posture Value of Backup • The most important thing that you store on your computer is information. • Often the contents of a hard disk can represent years of work. • If the hard disk stops working one day you could lose all those years of work. • For this reason it is VITAL that you take regular backups of the information that is stored on the computer. • Organize your computer for more efficient backups • Complete vs. incremental backups • Use off-site storage • Use passwords • Understand the Importance of shutting down your computer properly • Use a UPS (Un-interruptible Power Supply) Likes & Dislikes of Computer Things computer like: • Good ventilation • Clean environment • Stable, vibration free surface Things computer don’t like: • Dust • Drinking and eating over the keyboard • Heat, Cold or Moisture • Don’t place objects on top of monitors. • Don’t place floppy disks near monitors Computer Virus What are computer viruses? • Viruses are small programs that hide themselves on your disks (both diskettes and your hard disk). • Unless you use virus detection software the first time that you know that you have a virus is when it activates. • Different viruses are activated in different ways. How do viruses infect PCs? • Viruses hide on a disk and when you access the disk (either a diskette or another hard disk over a network) the virus program will start and infect your computer. • The worst thing about a computer virus is that they can spread from one computer to another, either via use of infected floppy disk, or over a computer network, including the Internet. How to prevent virus damage • There are a number of third party anti-virus products available. • Most of these are better than the rather rudimentary products available within DOS and Windows, but of course you do have to pay for them! • The main thing about your virus checker is that it should be kept up to date. • Many companies supply updated disks on a regular basis or allow you to receive updates through an electronic, on-line bulletin board.
Posted on: Mon, 25 Aug 2014 11:11:32 +0000
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