Potentbooks.files.wordpress.com



STA 2102 Introduction to Information Technology For StatisticsFrom 1960s to 1970s, the term information technology (IT) was a little known phrase that was used by those who worked in places like banks and hospitals to describe the processes they used to store information. With the paradigm shift to computing technology and "paperless" workplaces, information technology has come to be a household phrase.In a business context, the HYPERLINK "; \o "Information Technology Association of America" Information Technology Association of America has defined information technology (IT) as "the study, design, development, application, implementation, support or management of computer-based information systems. The business value of information technology is to automate business processes, provide information for decision making, connect business with their customers, and provide productivity tools to increase efficiency. In an academic context, the HYPERLINK "; \o "Association for Computing Machinery" Association for Computing Machinery defines it as "undergraduate degree programs that prepare students to meet the computer technology needs of business, government, healthcare, schools, and other kinds of organizations .... IT specialists assume responsibility for selecting hardware and software products appropriate for an organization, integrating those products with organizational needs and infrastructure, and installing, customizing, and maintaining those applications for the organization’s computer users. Examples of these responsibilities include the installation of networks; network administration and security; the design of web pages; the development of multimedia resources; the installation of communication components; the oversight of email systems; and the planning and management of the technology lifecycle by which an organization’s technology is maintained, upgraded, and replaced.It defines an industry that uses computers, networking, software programming, and other equipment and processes to store, process, retrieve, transmit, and protect information. Classification of puter: DefinitionA computer is a machine that can be programmed to manipulate symbols. Its principal characteristics are:It responds to a specific set of instructions in a well-defined manner.It can execute a prerecorded list of instructions (a program).It can quickly store and retrieve large amounts of data.Therefore computers can perform complex and repetitive procedures quickly, precisely and reliably. Modern computers are electronic and digital. The actual machinery (wires, transistors, and circuits) is called hardware; the instructions and data are called software. All general-purpose computers require the following hardware components:Components:Central processing unit (CPU): The heart of the computer, this is the component that actually executes instructions organized in programs ("software") which tell the computer what to do.Memory (fast, expensive, short-term memory): Enables a computer to store, at least temporarily, data, programs, and intermediate results.Mass storage device (slower, cheaper, long-term memory): Allows a computer to permanently retain large amounts of data and programs between jobs. Common mass storage devices include disk drives and tape drives.Input device: Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.Output device: A display screen, printer, or other devices that let you see what the computer has accomplished.In addition to these components, many others make it possible for the basic components to work together efficiently. For example, every computer requires a bus that transmits data from one part of the computer to puter sizes and powerComputers can be generally classified by size and power as follows, though there is considerable overlap:Personal computer: A small, single-user computer based on a microprocessor.Workstation: A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and, in general, a higher-quality monitor.Minicomputer: A multi-user computer capable of supporting up to hundreds of users simultaneously.Mainframe: A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.Supercomputer: An extremely fast computer that can perform hundreds of millions of instructions per second.Supercomputer and MainframeSupercomputer is a broad term for one of the fastest computers with very powerful and very fast processors currently available. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations (number crunching). For example, weather forecasting requires a supercomputer. Other uses of supercomputers scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (e.g. in petrochemical prospecting). Perhaps the best known supercomputer manufacturer is Cray Research.Mainframe was a term originally referring to the cabinet containing the central processor unit or "main frame" of a room-filling Stone Age batch machine. After the emergence of smaller "minicomputer" designs in the early 1970s, the traditional big iron machines were described as "mainframe computers" and eventually just as mainframes. Nowadays a Mainframe is a very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe. The distinction between small mainframes and minicomputers is vague, depending really on how the manufacturer wants to market its machines.?MinicomputerIt is a midsize computer. In the past decade, the distinction between large minicomputers and small mainframes has blurred, however, as has the distinction between small minicomputers and workstations. But in general, a minicomputer is a multiprocessing system capable of supporting from up to 200 users simultaneously.?WorkstationIt is a type of computer used for engineering applications (CAD/CAM), desktop publishing, software development, and other types of applications that require a moderate amount of computing power and relatively high quality graphics capabilities. Workstations generally come with a large, high-resolution graphics screen, at large amount of RAM, built-in network support, and a graphical user interface. Most workstations also have a mass storage device such as a disk drive, but a special type of workstation, called a diskless workstation, comes without a disk drive. The most common operating systems for workstations are UNIX and Windows . Like personal computers, most workstations are single-user computers. However, workstations are typically linked together to form a local-area network, although they can also be used as stand-alone systems.N.B.: In networking, workstation refers to any computer connected to a local-area network. It could be a workstation or a personal computer.?Personal computer:It can be defined as a small, relatively inexpensive computer designed for an individual user. In price, personal computers range anywhere from a few hundred dollers to over five thousand dollers. All are based on the microprocessor technology that enables manufacturers to put an entire CPU on one chip. Businesses use personal computers for word processing, accounting, desktop publishing, and for running spreadsheet and database management applications. At home, the most popular use for personal computers is for playing games and recently for surfing the Internet.Personal computers first appeared in the late 1970s. One of the first and most popular personal computers was the Apple II, introduced in 1977 by Apple Computer. During the late 1970s and early 1980s, new models and competing operating systems seemed to appear daily. Then, in 1981, IBM entered the fray with its first personal computer, known as the IBM PC. The IBM PC quickly became the personal computer of choice, and most other personal computer manufacturers fell by the wayside. P.C. is short for personal computer or IBM PC. One of the few companies to survive IBM's onslaught was Apple Computer, which remains a major player in the personal computer marketplace. Other companies adjusted to IBM's dominance by building IBM clones, computers that were internally almost the same as the IBM PC, but that cost less. Because IBM clones used the same microprocessors as IBM PCs, they were capable of running the same software. Over the years, IBM has lost much of its influence in directing the evolution of PCs. Therefore after the release of the first PC by IBM the term PC increasingly came to mean IBM or IBM-compatible personal computers, to the exclusion of other types of personal computers, such as Macintoshes. In recent years, the term PC has become more and more difficult to pin down. In general, though, it applies to any personal computer based on an Intel microprocessor, or on an Intel-compatible microprocessor. For nearly every other component, including the operating system, there are several options, all of which fall under the rubric of PCToday, the world of personal computers is basically divided between Apple Macintoshes and PCs. The principal characteristics of personal computers are that they are single-user systems and are based on microprocessors. However, although personal computers are designed as single-user systems, it is common to link them together to form a network. In terms of power, there is great variety. At the high end, the distinction between personal computers and workstations has faded. High-end models of the Macintosh and PC offer the same computing power and graphics capability as low-end workstations by Sun Microsystems, Hewlett-Packard, and DEC. Personal Computer TypesActual personal computers can be generally classified by size and chassis / case. The chassis or case is the metal frame that serves as the structural support for electronic components. Every computer system requires at least one chassis to house the circuit boards and wiring. The chassis also contains slots for expansion boards. If you want to insert more boards than there are slots, you will need an expansion chassis, which provides additional slots. There are two basic flavors of chassis designs–desktop models and tower models–but there are many variations on these two basic types. Then come the portable computers that are computers small enough to carry. Portable computers include notebook and subnotebook computers, hand-held computers, palmtops, and PDAs.Tower modelThe term refers to a computer in which the power supply, motherboard, and mass storage devices are stacked on top of each other in a cabinet. This is in contrast to desktop models, in which these components are housed in a more compact box. The main advantage of tower models is that there are fewer space constraints, which makes installation of additional storage devices easier.Desktop modelA computer designed to fit comfortably on top of a desk, typically with the monitor sitting on top of the computer. Desktop model computers are broad and low, whereas tower model computers are narrow and tall. Because of their shape, desktop model computers are generally limited to three internal mass storage devices. Desktop models designed to be very small are sometimes referred to as?slimline models.Notebook computerAn extremely lightweight personal computer. Notebook computers typically weigh less than 6 pounds and are small enough to fit easily in a briefcase. Aside from size, the principal difference between a notebook computer and a personal computer is the display screen. Notebook computers use a variety of techniques, known as flat-panel technologies, to produce a lightweight and non-bulky display screen. The quality of notebook display screens varies considerably. In terms of computing power, modern notebook computers are nearly equivalent to personal computers. They have the same CPUs, memory capacity, and disk drives. However, all this power in a small package is expensive. Notebook computers cost about twice as much as equivalent regular-sized computers. Notebook computers come with battery packs that enable you to run them without plugging them in. However, the batteries need to be recharged every few hours.Laptop computerA small, portable computer ,small enough that it can sit on your lap. Nowadays, laptop computers are more frequently called notebook computers.Subnotebook computerA portable computer that is slightly lighter and smaller than a full-sized notebook computer. Typically, subnotebook computers have a smaller keyboard and screen, but are otherwise equivalent to notebook computers.Hand-held computerA portable computer that is small enough to be held in one’s hand. Although extremely convenient to carry, handheld computers have not replaced notebook computers because of their small keyboards and screens. The most popular hand-held computers are those that are specifically designed to provide PIM (personal information manager) functions, such as a calendar and address book. Some manufacturers are trying to solve the small keyboard problem by replacing the keyboard with an electronic pen. However, these pen-based devices rely on handwriting recognition technologies, which are still in their infancy. Hand-held computers are also called PDAs, palmtops and pocket computers.PalmtopA small computer that literally fits in your palm. Compared to full-size computers, palmtops are severely limited, but they are practical for certain functions such as phone books and calendars. Palmtops that use a pen rather than a keyboard for input are often called hand-held computers or PDAs. Because of their small size, most palmtop computers do not include disk drives. However, many contain PCMCIA slots in which you can insert disk drives, modems, memory, and other devices. Palmtops are also called PDAs, hand-held computers and pocket computers.PDAShort for personal digital assistant, a handheld device that combines computing, telephone/fax, and networking features. A typical PDA can function as a cellular phone, fax sender, and personal organizer. Unlike portable computers, most PDAs are pen-based, using a stylus rather than a keyboard for input. This means that they also incorporate handwriting recognition features. Some PDAs can also react to voice input by using voice recognition technologies. The field of PDA was pioneered by Apple Computer, which introduced the Newton MessagePad in 1993. Shortly thereafter, several other manufacturers offered similar products. To date, PDAs have had only modest success in the marketplace, due to their high price tags and limited applications. However, many experts believe that PDAs will eventually become common gadgets.PDAs are also called palmtops, hand-held computers and pocket computers.Data vs Information - Differences in meaning Data are plain facts. When data are processed, organized, structured or presented in a given context so as to make them useful, they are called Information.Data on its own carries no meaning. For data to become information, it must be interpreted and take on a meaning.It is not enough to have data (such as HYPERLINK "; \o "Category:Statistics" statistics on the economy). Data in themselves are fairly useless. But when these data are interpreted and processed to determine its true meaning, they become useful and can be called Information. Data is the computer's language. Information is our translation of this language.BitIn HYPERLINK "; \o "Computing" computing, a bit can be defined as a HYPERLINK "(computer_science)" \o "Variable (computer science)" variable or computed quantity that can have only two possible HYPERLINK "(computer_science)" \o "Value (computer science)" values. These two values are often interpreted as HYPERLINK "; \o "Binary notation" binary digits and are usually denoted by the HYPERLINK "; \o "Numerical digit" numerical digits 0 and 1. The two values can also be interpreted as HYPERLINK "; \o "Truth value" logical values (true/false, yes/no), algebraic HYPERLINK "; \o "Signed number" signs (+/?), activation states (on/off), or any other two-valued attribute. The correspondence between these values and the physical states of the underlying HYPERLINK "; \o "Data storage device" storage or HYPERLINK "; \o "Computing device" device is a matter of convention, and different assignments may be used even within the same device or HYPERLINK "; \o "Computer program" program. The length of a binary number may be referred to as its " HYPERLINK "; \o "Bit-length" bit-length".ByteIn most computer systems, a byte is a unit of data that is eight bit long. A byte is the unit most computers use to represent a character such as a letter, number, or typographic symbol (for example, "g", "5", or "?"). A byte can also hold a string of bits that need to be used in some larger unit for application purposes (for example, the stream of bits that constitute a visual image for a program that displays images or the string of bits that constitutes the machine code of a computer program).In some computer systems, four bytes constitute a HYPERLINK "; word, a unit that a computer processor can be designed to handle efficiently as it reads and processes each instruction. Some computer processors can handle two-byte or single-byte instructions.A byte is abbreviated with a "B". (A bit is abbreviated with a small "b".) Computer storage is usually measured in byte multiples. For example, an 820 MB hard drive holds a nominal 820 million bytes - or megabytes - of data. Byte multiples are based on powers of 2 and commonly expressed as a "rounded off" decimal number. For example, one megabyte ("one million bytes") is actually 1,048,576 (decimal) bytes. (Confusingly, however, some hard disk manufacturers and dictionary sources state that bytes for computer storage should be calculated as powers of 10 so that a megabyte really would be one million decimal bytes.) Analog .Analog signals are a representation of time varying quantities in a continuous signal. Basically, a time variance is presented in a manner in which some sort of information is passed using various types of methods. These methods can include electrical, mechanical, hydraulic or pneumatic systems. Unlike digital signals, which use a numeric method of transmitting information, analog signals use small fluctuations in the signal itself to pass information.Analog signals act essentially like simulations of a continuous time varying quantity. They duplicate the features of the actual quantity by presenting a different quantity. In other words, they use one method of recording information and transfer it to a different format that, in turn, presents the information in that medium.Each analog signal uses a property of the final medium to convey the information for the signal. For example, a thermometer will utilize the heat of a particular object to determine its temperature. The heat is then transferred to mercury, which changes its position to display the temperature information on the gauge.The most common form of analog signal transmission occurs electrically. In order for this to happen, a voltage must be sent at a specific frequency. The flow of this electrical charge is known as current. By controlling the frequency of the current, information can be transmitted to another medium and presented on that medium. For example, magnetic tape on a cassette conveys information to the stereo which transmits it into electrical signals of specific frequencies which in turn tell the speakers what noise to make.Analog signals have a great advantage over digital signals in that they have a much higher density which can present more refined information. Essentially, there is the potential for the signal resolution to be infinite. In addition, the process to create an analog signal is achieved much more simply. By merely adjusting the time quantities, information can be presented.Disadvantages of the system include the tendency to create unwanted variations in the information transmission such as noise. These unwanted variations can occur in random patterns. When an analog signal is copied and potentially re-copied, each subsequent version exhibits more of the random patterns, making information transmission harder and ultimately causes signal loss.In order to avoid these disadvantages, or at least mitigate their effects, the concept of modulation can be used. The base analog signal is modified in some way to help retain the information as it is transmitted. An example of this is when the amplitude of a waveform is altered. This is known as amplitude modulation. Other options for retaining an electric signal over different generations by using increased shielding or different cable types twisted together.Digital.A digital signal is a way of transmitting data that converts the data to discrete values, usually based on the binary code that computer systems work upon, which consists of packets of information coded as strings of ones and zeros. Using digital signaling allows for an accurate and nearly identical copying of certain types of information like numbers, letters, or the individual pixel colors that make up images, and this information can be stored without long-term degradation of its quality. Where digital signal conversion occurs from what is originally an analog signal, however, such as with music or other natural wave forms, the end result is only an approximation of the original analog signal and some quality in digital format may be lost.While analog signals are based upon natural processes that utilize the electromagnetic wave forms by which electricity and light are transmitted, digital signal processing requires a digital signal converter. A modulator-demodulator (modem) is such a device. It receives analog signals either from air wave transmissions or telephone lines, and converts them to digital signals that a computer or modern digital television can display as useful information.Analog signal transmission has been a common form of transmission in technology since the 1800s, but, as of 2007, it is estimated that over 94% of stored and transmitted information has become digital world wide. This is up from only 3% for digital storage in 1993, and the reasons given for switching to digital signal transmissions is often one of capacity and noise. Analog signals can only be transmitted within a defined range for wavelengths, and, when the signal reaches outside this range or is interfered with by other analog signals along similar wavelengths, distortions and noise can degrade the value of the signal. Since digital signals are based upon a discrete on/off transmission principle, they have far less susceptibility to corruption over long distances. A digital signal can also be broken up into separate packets of information known as computer bytes and sent individually to a destination where they are reassembled. This allows for a much more efficient means of transmitting data along randomized networks such as that of the Internet, and it also increases the speed of data transmission over all.One of the main drawbacks to a digital TV signal or digital cable signal, for instance, is that it is an artificial reproduction of the original data, whereas an analog signal starts out as an exact copy of the original. As a digital signal is translated by multiple devices, encoded as analog and decoded as digital, and reassembled at the end point, quality in the reproduction can be lost. This is due to the fact that digital signals are often copies of copies of copies, and, in the process, approximations must be made by technology to replicate what the original signal was. Wireless digital transmissions can also be corrupted by other wireless activity in the area or radio signals that interfere with them, though this tends to be less of a problem than signal corruption in over the air analog transmissions.Analog and digital signals are used to transmit information, usually through electric signals. In both these technologies, the information, such as any audio or video, is transformed into electric signals. The difference between analog and digital technologies is that in analog technology, information is translated into electric pulses of varying amplitude. In digital technology, translation of information is into binary format (zero or one) where each bit is representative of two distinct amplitudes.Properties of Digital vs Analog signalsDigital information has certain properties that distinguish it from analog communication methods. These include Synchronization – digital communication uses specific synchronization sequences for determining synchronization.Language – digital communications requires a language which should be possessed by both sender and receiver and should specify meaning of symbol sequences.Errors – disturbances in analog communication causes errors in actual intended communication but disturbances in digital communication does not cause errors enabling error free communication. Errors should be able to substitute, insert or delete symbols to be expressed. Copying – analog communication copies are quality wise not as good as their originals while due to error free digital communication, copies can be made indefinitely.Granularity – for a continuously variable analog value to be represented in digital form there occur quantization error which is difference in actual analog value and digital representation and this property of digital communication is known as granularity.Differences in Usage in EquipmentMany devices come with built in translation facilities from analog to digital. Microphones and speaker are perfect examples of analog devices. Analog technology is cheaper but there is a limitation of size of data that can be transmitted at a given time. Digital technology has revolutionized the way most of the equipments work. Data is converted into binary code and then reassembled back into original form at reception point. Since these can be easily manipulated, it offers a wider range of options. Digital equipment is more expensive than analog parison of Analog vs Digital QualityDigital devices translate and reassemble data and in the process are more prone to loss of quality as compared to analog devices. Computer advancement has enabled use of error detection and error correction techniques to remove disturbances artificially from digital signals and improve quality. Differences in ApplicationsDigital technology has been most efficient in cellular phone industry. Analog phones have become redundant even though sound clarity and quality was better. Analog technology comprises of natural signals like human speech. With digital technology this human speech can be saved and stored in a computer. Thus digital technology opens up the horizon for endless possible uses. INPUT UNIT Input unit accepts coded information from human operators through electromechanical devices such as the keyboard or from other computers over digital communication lines. The information received is either stored in the memory for later reference or immediately used by the Arithmetic and Logic circuitry to perform the desired operation. Finally the result is sent back to the outside through the output unit. The keyboard is wired so that whenever a key is pressed, the corresponding letter or digit is automatically translated into its corresponding code and sent directly to either the memory or the processor. Other kinds of input devices: Joy stick, track ball, mouse (pointing devices), scanner etc. OUTPUT UNIT Output devices accept binary data from the computer - decodes it into original form and supplies this result to the outside world. E.g. Monitors, Printer, Video terminals (provides both input & output functions), graphic displays etc.MEMORY UNIT The memory unit stores program and data. There are two classes of memory devices :- Primary memory and Secondary memory. Primary memory (Main memory) Contains a large number of semiconductor cells each capable of storing one bit of information These cells are processed in group of fixed size called words containing ‘n’ bits. The main memory is organized such that the contents of one word can be stored or retrieved in one basic operation. For accessing data, a distinct address is associated with each word location. Data and programs must be in the primary memory for execution. Number of bits in each word is called the word length and it may vary from 16 to 64 bits. Fast memory Expensive Time required to access one word is called Memory Access Time - 10nS to 100nS. This time is fixed and independent of the location. Secondary storage They are used when large amount of data have to be stored (also when frequent access is not necessary) CENTRAL PROCESSING UNIT ( CPU ) The heart of the computer system is the Processor unit. It consists of Arithmetic and Logic Unit and Control Unit. Arithmetic and Logic Unit (ALU) Most computer operations (Arithmetical and logical data) are executed in ALU of the processor. For example: Suppose two numbers (operands) located in the main memory are to be added. These operands are brought into arithmetic unit – actual addition is carried. The result is then stored in the memory or retained in the processor itself for immediate use. Note that all operands may not reside in the main memory. Processor contains a number of high speed storage elements called Registers, which may be used for temporary storage of frequently used operands. Each register can store one word of data. Access times to registers are 5 to 10 times faster than access time to memory. Control Unit The operations of all the units are coordinated by the control unity (act as the nerve center that sends control signal to other units) Timing signal that governs the I/O transfers are generated by the Control Unit. Synchronization signals are also generated by the Control Unit By selecting, interpreting and executing the program instructions the control unit is able to maintain order and direct the operation of the entire system. The control unit and ALU’s are usually many times faster than other devices connected to a computer system. This enabled a single processor to control a number of external devices such as video terminals, magnetic taped, disk memories, sensors, displays and mechanical controllers which are much slower than the processor.INTERNAL ORGANIZATION OF PROCESSOR Processor contains a number of registers used for temporary storage of data other than ALU and Control circuitry Instruction Register (IR) – holds the instruction that is currently being executed – its output is available to the control circuits which generate the timing signals that control the various processing elements involved in executing the instruction. Program Counter (PC) – It contains the address of the instruction currently being executed. During the execution of an instruction, the contents of the program counter are updated to hold the address of the next instruction to be executed. i.e. PC points to the next instruction that is to be fetched from the memory. General Purpose Registers (R0 to Rn-1) – Facilitates communication with the main memory. Access to data in these registers is much faster than to data stored in memory locations because the registers are inside the processor. Most modern computers have 8 to 32 general purpose registers. Memory Address Register (MAR) – holds the address of the location to or from which data are to be transferred Memory Data Register (MDR) – contains the data to be written into or read out of the address location.The answer may be a bit more involved than you would expect, because there are a perhaps surprisingly large number of different kinds of storage devices. The outline below seeks to identify these and to provide a logical way of organizing them.System Software System software is a program that manages and supports the computer resources and operations of a computer system while it executes various tasks such as processing data and information, controlling hardware components, and allowing users to use application software. That is, systems software functions as a bridge between computer system hardware and the application software. System software is made up of many control programs, including the operating system, communications software and database manager. There are many kinds of computers these days. Some of them are easier to learn than others. Some of them perform better than others. These differences may come from different systems software. Three Kinds of Programs Systems software consists of three kinds of programs. The system management programs, system support programs, and system development programs. These are explained briefly. System Management Programs These are programs that manage the application software, computer hardware, and data resources of the computer system. These programs include operating systems, operating environment programs, database management programs, and telecommunications monitor programs. Among these, the most important system management programs are operating systems. The operating systems needs to be studied in more details. There are two reasons. First, users need to know their functions first. For the second, there are many kinds of operating systems available today. Telecommunications monitor programs are additions of the operating systems of microcomputers. These programs provide the extra logic for the computer system to control a class of communications devices. System Support Programs These are the programs that help the operations and management of a computer system. They provide a variety of support services to let the computer hardware and other system programs run efficiently. The major system support programs are system utility programs, system performance monitor programs, and system security monitor programs (virus checking programs). System Development Programs These are programs that help users develop information system programs and prepare user programs for computer processing. These programs may analyze and design systems and program itself. The main system development programs are programming language translators, programming environment programs, computer-aided software engineering packages. Operating Systems An operating system is a collection of integrated computer programs that provide recurring services to other programs or to the user of a computer. These services consist of disk and file management, memory management, and device management. In other words, it manages CPU operations, input/output activities, storage resources, diverse support services, and controls various devices.Operating system is the most important program for computer system. Without an operating system, every computer program would have to contain instructions telling the hardware each step the hardware should take to do its job, such as storing a file on a disk. Because the operating system contains these instructions, any program can call on the operating system when a service is needed. Need to Study Operating System? There are many different computer systems and several available operating systems. Thus, users must know what each operating system can do and cannot do to meet their necessity. Today, many operating systems are used for general use or sometimes for specific use. Then, which one is best for a specific purpose? The reason that users need to study operating system is here.The predominant microcomputer operating system for IBM and IBM-compatibles so far was DOS (Disk Operating System). It has different versions including MS-DOS, PC-DOS and others. DOS is very popular and wide spread, but it has some limitations. Users need to learn DOS although it may fade out in a few years and has some weakness, because it will be used for the next several years. The other popular operating system was the Apple Macintosh operating system.As more powerful microcomputers become commonplace, more advanced operating systems are needed. Microcomputer users are beginning to demand more powerful operating system that can run powerful microcomputers more efficiently. Today's very powerful microcomputers are demanding more complex and refined operating system that can do multifunctions. They also ask an easier user interface than old operating systems did. Now, there are more than six popular operating systems, leading to the lack of a standard. The other reason that operating system should be learned is here. How the Operating System Uses Memory Here explains in case of DOS. When a personal computer is turned on, it searches specific locations on the disk drives for operating system files. If the PC finds the files, it loads the first of them into memory. A set of operating system files then takes over, loading the rest of the main files into memory in a specific order. Because the operating system is in a sense, loading itself or lifting itself by its own bootstraps, this operation is called the boot-up.At the lowest part of memory, the operating system loads a table of interrupt vectors. When the operating system receives special codes called interrupts, it uses the table to detect where in memory it can find matching instructions. DOS also uses a small area just above the interruption table to hold the BIOS data called 'flags' that record the state of various system conditions. The same area also acts as a buffer to store keystrokes that come in faster than the system can process them.A large expanse of memory just above the BIOS flags and keyboard buffer is used for device drivers, utility programs, and application programs. When DOS reads the CONFIG.SYS and AUTOEXEC.BAT files, it looks for command lines to load drivers or memory-resident programs. Memory- resident programs are those that continue to be active even when application programs are running. When it finds such a command line, DOS normally puts the driver or program at the start of this large memory area. Device drivers usually remain loaded until the PC is turned off. Memory- resident programs can be unloaded if no other programs are loaded after them. Operating System Functions An operating system executes many functions to operate computer system efficiently. Among them, four essential functions are the followings. Resource Management: An operating system manages a collection of computer hardware resources by using a variety of programs. It manages computer system resources, including its CPU, primary memory, virtual memory, secondary storage devices, input/output peripherals, and other devices. Task Management: The function of the operating system that controls the running of many tasks. It manages one program or many programs within a computer system simultaneously. That is, this function of operating system manages the completion of users' tasks. A task management program in an operating system provides each task and interrupts the CPU operations to manage tasks efficiently. Task management may involve a multitasking capability. File management: This is a function that manages data files. An operating system contains file management programs that provide the ability to create, delete, enter, change, ask, and access of files of data. They also produce reports on a file. User Interface: It is a function of an operating system that allows users to interact with a computer. A user interface program may include a combination of menus, screen design, keyboard commands. A well-designed user interface is essential for an operating system to be popular. Because of the function, users can load programs, access files, and accomplish other tasks. Utility software.Utility software?is? HYPERLINK "; system software?designed to help analyze, configure, optimize or maintain a computer. A single piece of utility software is usually called a?utility?or?tool.Utility software usually focuses on?how?the computer infrastructure (including the? HYPERLINK "; computer hardware,? HYPERLINK "; operating system,? HYPERLINK "; application software?and? HYPERLINK "(computing)" data?storage) operates. Due to this focus, utilities are often rather technical and targeted at people with an advanced level of computer knowledge - in contrast to? HYPERLINK "; application software, which allows users to do things like creating text documents, playing games, listening to music or viewing websites.Types of utilities HYPERLINK "; Anti-virus?utilities scan for computer viruses. HYPERLINK "; Backup?utilities can make a copy of all information stored on a disk, and restore either the entire disk (e.g. in an event of? HYPERLINK "; disk failure) or selected files (e.g. in an event of accidental deletion). HYPERLINK "; Data compression?utilities output a shorter stream or a smaller file when provided with a stream or file. HYPERLINK "; Disk checkers?can scan operating hard drive. HYPERLINK "; Disk cleaners?can find files that are unnecessary to computer operation, or take up considerable amounts of space. Disk cleaner helps the? HYPERLINK "(computing)" user?to decide what to? HYPERLINK "; delete?when their hard disk is full. HYPERLINK "; Disk compression?utilities can transparently? HYPERLINK "; compress/uncompress the contents of a disk, increasing the capacity of the disk. HYPERLINK "; Disk defragmenters?can detect? HYPERLINK "; computer files?whose contents are broken across several locations on the? HYPERLINK "; hard disk, and move the fragments to one location to increase efficiency. HYPERLINK "; Disk partitions?can divide an individual drive into multiple logical drives, each with its own file system which can be mounted by the operating system and treated as an individual drive. HYPERLINK "; Disk space analyzers?for the visualization of disk space usage by getting the size for each folder (including sub folders) & files in folder or drive. showing the distribution of the used space. HYPERLINK "; Disk storage?utilities HYPERLINK "; Archive?utilities output a stream or a single file when provided with a directory or a set of files. Archive utilities, unlike archive suites, usually do not include compression or encryption capabilities. Some archive utilities may even have a separate un-archive utility for the reverse operation. HYPERLINK "; File managers?provide a convenient method of performing routine data management tasks, such as deleting, renaming, cataloging, uncataloging, moving, copying, merging, generating and modifying data sets. HYPERLINK "; Cryptographic?utilities encrypt and decrypt streams and files. HYPERLINK "; Hex editors?directly modify the text or data of a file. These files could be data or an actual program. HYPERLINK "; Memory testers?check for memory failures. HYPERLINK "; Network utilities?analyze the computer's network connectivity, configure network settings, check data transfer or log events. HYPERLINK "; Registry cleaners?clean and optimize the? HYPERLINK "; Windows registry?by removing old registry keys that are no longer in use. HYPERLINK "; Screensavers?were desired to prevent? HYPERLINK "; phosphor burn-in?on? HYPERLINK "; CRT?and plasma? HYPERLINK "; computer monitors?by blanking the screen or filling it with moving images or patterns when the computer is not in use. Contemporary screensavers are used primarily for entertainment or security. HYPERLINK "; System monitors?for monitoring resources and performance in a computer system. HYPERLINK "; System profilers?provide detailed information about the software installed and hardware attached to the piling Program.A compiler is a HYPERLINK "; \o "Computer program" computer program (or set of programs) that transforms HYPERLINK "; \o "Source code" source code written in a HYPERLINK "; \o "Programming language" programming language (the source language) into another computer language (the target language, often having a binary form known as HYPERLINK "; \o "Object code" object code). The most common reason for wanting to transform source code is to create an HYPERLINK "; \o "Executable" executable program.The name "compiler" is primarily used for programs that translate source code from a HYPERLINK "; \o "High-level programming language" high-level programming language to a lower level language (e.g., HYPERLINK "; \o "Assembly language" assembly language or HYPERLINK "; \o "Machine code" machine code). If the compiled program can run on a computer whose HYPERLINK "; \o "CPU" CPU or HYPERLINK "; \o "Operating system" operating system is different from the one on which the compiler runs, the compiler is known as a HYPERLINK "; \o "Cross-compiler" cross-compiler. A program that translates from a low level language to a higher level one is a HYPERLINK "; \o "Decompiler" decompiler. A program that translates between high-level languages is usually called a HYPERLINK "(computing)" \o "Translator (computing)" language translator, source to source translator, or language converter. A language HYPERLINK "; \o "Rewriting" rewriter is usually a program that translates the form of expressions without a change of language.A compiler is likely to perform many or all of the following operations: HYPERLINK "; \o "Lexical analysis" lexical analysis, HYPERLINK "; \o "Preprocessing" preprocessing, HYPERLINK "; \o "Parsing" parsing, semantic analysis ( HYPERLINK "; \o "Syntax-directed translation" Syntax-directed translation), HYPERLINK "(compiler)" \o "Code generation (compiler)" code generation, and HYPERLINK "; \o "Code optimization" code optimization.Program faults caused by incorrect compiler behavior can be very difficult to track down and work around; therefore, compiler implementors invest significant effort to ensure the HYPERLINK "; \o "Compiler correctness" correctness of their software.The term HYPERLINK "; \o "Compiler-compiler" compiler-compiler is sometimes used to refer to a HYPERLINK "; \o "Parser generator" parser generator, a tool often used to help create the HYPERLINK "; \o "Lexical analysis" lexer and HYPERLINK "; \o "Parser" parser.Data files?A?data file?is a? HYPERLINK "; \o "Computer file" computer file?which stores data to use by a computer? HYPERLINK "; \o "Application software" application?or? HYPERLINK "; \o "System software" system. It generally does?not?refer to files that contain instructions or code to be executed (typically called program files), or to files which define the operation or structure of an application or system (which include configuration files, directory files, etc.); but specifically to information used as input, or written as output by some other software program. This is especially helpful when debugging a program. Most computer programs work with? HYPERLINK "; \o "File" files. This is because files help in storing information permanently.? HYPERLINK "; \o "Database" Database?programs create files of information.? HYPERLINK "; \o "Compiler" Compilers?read source files and generate executable files. A file itself is a bunch of? HYPERLINK "; \o "Byte" bytes?stored on some storage device like? HYPERLINK "; \o "Tape" tape,? HYPERLINK "; \o "Magnetic disk" magnetic disk,? HYPERLINK "; \o "Optical disk" Optical disk?etc. The?data files?are the files that store data pertaining to a specific application, for later use.SERIAL FILEA?serial file?consists of sets of data of the same record type (but usually the records are of different lengths) that is stored?in the same order in which the records were created. They have not been sorted. Examples are transaction files (in which sales are added to the file as they occur) or shopping lists, in which items are added to the end of the list as you think of them.A search of a serial file is performed by sequential comparison of the query with identifiers of?all?stored items.CSV (comma-separated values) is a common serial/sequential file format in which text fields are delimited by commas.PROs and CONs of SEQUENTIAL FILESIn serial files, to read item N, all items from 1 to N-1 must be read first. It is impossible to jump directly to a particular record. This makes serial files?simple and fast to create, but?slow and awkward to use later.Think of a library where books are stacked in the order in which they are bought, and to find a particular book, you start at the first one and keep searching until you eventually find the one you want.Unlike?random access files?in which you can instantly access any record without having to traverse all the records between where you are and where you want to be.Think of serial & sequential files as cassette tape: if you want to listen to song 13, you have to fast-forward or rewind from your current position to the start of song 13. Compare it to a CD where you can lift the read head and drop it exactly where it needs to read next.RANDOM ACCESSRandom access files have a?predictable, strict structure?that lets you directly seek and go to the start of a desired record. This structure is only possible because each record has a fixed length.A random file may be define as follows:STRUCTURE?SalesRecordSurname?AS TEXT?* 15Firstname?AS TEXT?* 10Quantity?AS INTItemName?AS TEXT?* 20SaleTotal?AS CURRENCYSaleDate?AS DATEEND STRUCTUREPROs and CONs RANDOM ACCESS FILESWhile random files are?faster?to search and access, they can both?waste storage space?and potentially?cut off data. e.g. if a name field in a random file's record is defined as being 15 characters long, the name "JONES" would have 10 bytes excess. When design random file records, considerable thought needs to go into choosing the maximum lengths of fields to prevent problems later.A?disk drive track?is a circular path on the surface of a disk or diskette on which information is magnetically recorded and from which recorded information is read.A?track?is a physical division of data in a disk drive, as used in the Cylinder-Head-Record (CCHHRR) addressing mode of a? HYPERLINK "; \o "CKD disk" CKD disk. The concept is concentric, through the physical? HYPERLINK "; \o "Hard disk platter" platters, being a data circle per each cylinder of the whole disk drive. In other words, the number of tracks on a single surface in the drive exactly equals the number of cylinders of the drive.Tracks are subdivided into blocks (or sectors, pages)?In computer disk storage, a?sector?is a subdivision of a? HYPERLINK "(disk_drive)" \o "Track (disk drive)" track?on a? HYPERLINK "; \o "Magnetic disk" magnetic disk?or? HYPERLINK "; \o "Optical disc" optical disc. Each sector stores a fixed amount of user data. Traditional formatting of these storage media provides space for 512? HYPERLINK "; \o "Byte" bytes?or 2048 bytes of user-accessible data per hertz. Newer hard drives use 4096 byte (4?KB or 4K)? HYPERLINK "; \o "Advanced Format" Advanced Format?sectors.Mathematically, the word? HYPERLINK "; \o "Sector" sector?means a portion of a? HYPERLINK "; \o "Disk" disk?between a center, two? HYPERLINK "; \o "Radius" radii?and a corresponding? which is shaped like a slice of a pie. Thus, the?disk sector?refers to the intersection of a?track?and mathematical sector.In disk drives, each physical sector is made up of three basic parts, the sector header, the data area and the? HYPERLINK "; \o "Error-correcting code" error-correcting code(ECC). The sector header contains information used by the drive and controller. This information includes sync bytes,?address identification, flaw flag and header parity bytes. The header may also include an alternate address to be used if the data area is undependable. The?address identification?is used to ensure that the mechanics of the drive have positioned the read/write head over the correct location. The data area contains the recorded user data. The ECC field contains codes based on the data field, which are used to check and possibly correct errors that may have been introduced into the data.Cluster.Storage clustering, also referred to as grid storage, is a new technology paradigm that pushes the scalability and efficiency boundaries of storage area networks (SANs) to new levels. Clustered storage is similar to clustered computing, providing an on-demand shared storage environment similar to the cluster model for compute resources. Storage clusters are made up of storage server farms linked together that work on similar tasks in a grid fashion by scaling out infrastructure as opposed to scaling up with larger and more powerful machines.Clustered storage systems are typically made up of network-connected storage with an administrative function that manages a collection of physical disks. To a client or application server, this collection appears as a highly available block-level storage system that provides a large abstract pool of disks, or storage cluster. Storage clusters are accessible to all clients on the network. A client can create a volume in a cluster on demand to tap the entire capacity of the underlying physical resources. Furthermore, additional storage resources can be automatically incorporated into the storage cluster. Storage clustering provides clients with a virtual volume pool that can tolerate and recover from disk, server, and network failures.Clustered storage offerings are common in the market today, but the majority of these solutions are based on legacy “scale-up” architectures. This legacy storage clustering technology requires a master controller or “head” to coordinate tasks among the nodes in the cluster. This architecture can introduce a single point of failure and presents a bottleneck that limits scalability—as you add storage servers they contend for the master controller’s resources and performance is impeded. If the master controller function is in the I/O path, referred to as in-band, every I/O operation goes through a management software stack before it’s stored on disk. This approach severely limits performance and can introduce reliability issues in the data path by performing master controller operations on I/O that the application may not be aware of, possibly resulting in unpredictable behavior. This is especially true when caching is involved. The challenge has been to develop a clustering technology that provides all the centralized management benefits from these legacy “scale up” technologies without sacrificing performance, reliability and availability.Newly introduced storage clustering technology addresses these challenges by distributing the “master” or management functionality across multiple storage servers. These storage servers are in effect purpose-built master controllers. These storage servers, combined with distributed system software, are designed to be a peer in the storage cluster or grid. This storage clustering technology is defined as a parallel and distributed system that enables the sharing, selection and aggregation of storage resources distributed across multiple administrative domains. This implementation distributes the management task across multiple storage servers, eliminating any single point of failure and allowing the management function to scale as the cluster scales.This distributed management function is not in the data path (referred to as out-of-band) and all I/O is performed directly from the server application to the disk. Distributed storage clusters can provide tremendous aggregate throughput by combining the strengths of multiple servers, aggregating processors and memory, with multiple SAN and network interfaces and a nearly unlimited number of storage servers. All components can be upgraded and serviced while the overall functionality and services of the cluster remain online. This distributed systems architecture also eliminates the single point of failure common with other clustering technologies by replicating data across storage servers, allowing the cluster to survive the loss of one or more storage serversDistributing the storage management intelligence also allows storage to be managed and synchronized across multiple geographic locations. Performing remote data replication with distributed management almost completely removes the burden of replication from host systems.The storage cluster is an aggregate resource with a single system image regardless of the number of storage servers in the cluster, greatly simplifying cluster administration. Configuration and management tasks that would otherwise have to be repeated many times can be performed in a single location and automatically synchronize all cluster members. The cluster appears as a single storage system for attachment to servers.This single system image functionality is often referred to as virtualization, where the application servers see a single storage image that represents the aggregate capacity of all storage server arrays. Virtualization provides the capability to aggregate the storage environment so that the administrator does not have to plan and provision storage on disparate arrays.More advanced virtualization technology includes the ability to automatically load balance and allocate data across storage servers, optimizing performance and storage utilization. Dynamic load balancing eliminates system bottlenecks by ensuring uniform load distribution even in the face of component failure. If an application requires more storage resources, the distributed storage system is able to efficiently tie the additional resources together transparently and reallocate data on the fly. Storage servers can also be upgraded and serviced while the overall functionality of the cluster remains on-line and services provided by the cluster remain unaffected.SummaryManaging large storage systems has historically been an expensive and complicated process. Often a single component failure can halt the entire system and require considerable time and effort to resume operation. Moreover, the capacity and performance of individual components in the system must be periodically monitored and balanced to reduce fragmentation and eliminate hot spots. This usually requires manually moving, partitioning, or replicating files and directories.Distributed storage clustering or grid storage overcomes these limitations of legacy storage architectures, delivering a wide range of benefits:Scalability of performance, capacity and availability in small and modular incrementsEasy management of a single system imageNon-disruptive data movementHigher utilization ratesLower hardware acquisition costsAbility to sustain failure of multiple elements without affecting data accessDistributed storage clustering greatly impacts the ability to build cost-effective SANs. By simplifying the management task and allowing for lower-cost SAN implementations, distributed storage clustering will allow the mid-tier market to take advantage of features available only with SANs such as high availability, snapshot, replication, and remote data movement.Variable-length code.?In? HYPERLINK "; \o "Coding theory" coding theory?a?variable-length code?is a? HYPERLINK "; \o "Code" code?which maps source symbols to a?variable?number of mon codes use a constant code length for any symbol. Therefore the coding procedure is easy to implement, an adaption to symbols frequently occurring do not take place. ie. symbols with a high frequency will get the same code length than rare ones.Using a variable code length would provide a higher code efficiency, as far as the original data are suitable. Therefore procedures has to be implemented assigning short codes to symbols occurring frequently and long codes to rare ones. In total this will result in savings occasionally on a large scale. Detailed statements about code lengths required and statistical fundamentals will be made by information theory.Some important requirements have to be matched using variable length codes in practice. Otherwise a faultless encoding and decoding process cannot be guaranteed.Requirements for variable length codes:unambiguous interpretationflexible distribution of code lengthslow coding effortExamples for variable length codes:Huffman codingShannon-Fano codingSomtimes "Variable Length Coding" is referred to as "Variable Length Encoding". The abbreviations VLC and VLE are in use.Variable-length codes can allow sources to be? HYPERLINK "; \o "Data compression" compressed?and decompressed with?zero?error ( HYPERLINK "; \o "Lossless data compression" lossless data compression) and still be read back symbol by symbol. With the right coding strategy an? HYPERLINK "; \o "Independent and identically-distributed random variables" independent and identically-distributed source?may be compressed almost arbitrarily close to its? HYPERLINK "; \o "Information entropy" entropy. This is in contrast to fixed length coding methods, for which data compression is only possible for large blocks of data, and any compression beyond the logarithm of the total number of possibilities comes with a finite (though perhaps arbitrarily small) probability of failure.ASCIIStands for "American Standard Code for Information Interchange." ASCII? HYPERLINK "; character encoding?provides a the standard for representing all upper-case and lower-case Latin letters, numbers, punctuations, etc as a code number used by computers.ASCII uses 7? HYPERLINK "; bits?to represent each character. For example, a capital "T" is represented by the number 84 and a lowercase "t" is represented by 116. Other HYPERLINK "; keyboard?keys are also mapped to standard ASCII values. For example, the Escape (ESC) key is represented as 27 and the Delete (DEL) key is represented as 32. ASCII codes may also be displayed as? HYPERLINK "; hexadecimal?values instead of the decimal numbers listed above. For example, the ASCII value of the Escape key in hexadecimal is "1B" and the hexadecimal value of the Delete key is "7F."Since ASCII uses 7 bits, it only supports 2^7, or 128 values. Therefore, the standard ASCII character set is limited to 128 characters. While this is enough to represent all standard English letters, numbers, and punctuation symbols, it is not sufficient to represent all special characters or characters from other languages. Even Extended ASCII, which supports 8 bit values, or 256 characters, does not include enough characters to accurately represent all languages. Therefore, other character sets, such as Latin-1 (ISO-8859-1), UTF-8, and UTF-16 are commonly used for HYPERLINK "; documents?and? HYPERLINK "; webpages?that require more characters.IntegerAn integer is a HYPERLINK "; \o "Number" number that can be written without a fractional or decimal component. For example, 21, 4, and ?2048 are integers; 9.75, 5?, and √2 are not integers. The set of integers is a subset of the HYPERLINK "; \o "Real number" real numbers, and consists of the HYPERLINK "; \o "Natural numbers" natural numbers ( HYPERLINK "(number)" \o "0 (number)" 0, HYPERLINK "(number)" \o "1 (number)" 1, HYPERLINK "(number)" \o "2 (number)" 2, HYPERLINK "(number)" \o "3 (number)" 3, ...) and the HYPERLINK "; \o "Negative number" negatives of the non-zero natural numbers ( HYPERLINK "(number)" \o "?1 (number)" ?1, ?2, ?3, ...).The name derives from the HYPERLINK "; \o "Latin" Latin integer (meaning literally "untouched," hence "whole": the word entire comes from the same origin, but via French HYPERLINK "; \l "cite_note-1" [1]). The HYPERLINK "(mathematics)" \o "Set (mathematics)" set of all integers is often denoted by a boldface Z (or HYPERLINK "; \o "Blackboard bold" blackboard bold , HYPERLINK "; \o "Unicode" Unicode U+2124 ?), which stands for HYPERLINK "; \o "wiktionary:Zahlen" Zahlen ( HYPERLINK "; \o "German language" German for numbers, pronounced HYPERLINK "; \o "Help:IPA for German" [?tsa?l?n]). HYPERLINK "; \l "cite_note-2" [2]The integers (with addition as operation) form the smallest HYPERLINK "(mathematics)" \o "Group (mathematics)" group containing the additive HYPERLINK "; \o "Monoid" monoid of the HYPERLINK "; \o "Natural number" natural numbers. Like the natural numbers, the integers form a HYPERLINK "; \o "Countable set" countable infinite set. In HYPERLINK "; \o "Algebraic number theory" algebraic number theory, these commonly understood integers, embedded in the HYPERLINK "(mathematics)" \o "Field (mathematics)" field of HYPERLINK "; \o "Rational number" rational numbers, are referred to as rational integers to distinguish them from the more broadly defined HYPERLINK "; \o "Algebraic integer" algebraic integers.?Fractions?A?fraction?(from Latin:?fractus, "broken") represents a part of a whole or, more generally, any number of equal parts. When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight-fifths, three-quarters.A?common,?vulgar, or?simple?fraction (for example?,?, and 3/17) consists of an? HYPERLINK "; \o "Integer" integer?numerator, displayed above a line (or before a slash), and a non-zero integer?denominator, displayed below (or after) that line. The numerator represents a number of equal parts and the denominator indicates how many of those parts make up a whole. For example, in the fraction 3/4, the numerator, 3, tells us that the fraction represents 3 equal parts, and the denominator, 4, tells us that 4 parts make up a whole.?Single Precision.?When used to describe? HYPERLINK "; floating-point numbers, the number of? HYPERLINK "; bits?used to hold the fractional part. The more precision a? HYPERLINK "; system?uses, the more exactly it can represent fractional quantities.Floating-point numbers are often classified as?single precision?or? HYPERLINK "; double precision. A double-precision number uses twice as many bits as a single-precision value, so it can represent fractional quantities much more exactly.double precisionRefers to a type of? HYPERLINK "; floating-point number?that has more? HYPERLINK "; precision?(that is, more digits to the right of the decimal point) than a?single-precision?number. The term?double precision?is something of a misnomer because the precision is not really double. The word?double?derives from the fact that a double-precision number uses twice as many? HYPERLINK "; bits?as a regular floating-point number. For example, if a single-precision number requires 32 bits, its double-precision counterpart will be 64 bits long.The extra bits increase not only the precision but also the range of magnitudes that can be represented. The exact amount by which the precision and range of magnitudes are increased depends on what? HYPERLINK "; formatthe? HYPERLINK "; program?is using to represent floating-point values. Most? HYPERLINK "; computers?use a HYPERLINK "; standard?format known as the? HYPERLINK "; IEEE?floating-point format.Binary NumbersHow Computers Store NumbersComputer systems are constructed of digital electronics. That means that their electronic circuits can exist in only one of two states: on or off. Most computer electronics use voltage levels to indicate their present state. For example, a transistor with five volts would be considered "on", while a transistor with no voltage would be considered "off." Not all computer hardware uses voltage, however.?CD-ROM's, for example, use microscopic dark spots on the surface of the disk to indicate "off," while the ordinary shiny surface is considered "on." Hard disks use magnetism, while computer memory uses electric charges stored in tiny capacitors to indicate "on" or "off."These patterns of "on" and "off" stored inside the computer are used to encode numbers using thebinary number system.?The binary number system is a method of storing ordinary numbers such as 42 or 365 as patterns of 1's and 0's. Because of their digital nature, a computer's electronics can easily manipulate numbers stored in binary by treating 1 as "on" and 0 as "off." Computers have circuits that can add, subtract, multiply, divide, and do many other things to numbers stored in binary.How Binary WorksThe decimal number system that people use every day contains ten digits, 0 through 9. Start counting in decimal: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, Oops! There are no more digits left. How do we continue counting with only ten digits? We add a second column of digits, worth ten times the value of the first column. Start counting again: 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 (Note that the right column goes back to zero here.), 21, 22, 23, ... , 94, 95, 96, 97, 98, 99, Oops! Once again, there are no more digits left. The only way to continue counting is to add yet another column worth ten times as much as the one before. Continue counting: 100, 101, 102, ... 997, 998, 999, 1000, 1001, 1002, .... You should get the picture at this point.Another way to make this clear is to write decimal numbers in expanded notation. 365, for example, is equal to 3×100 + 6×10 + 5×1. 1032 is equal to 1×1000 + 0×100 + 3×10 + 2×1. By writing numbers in this form, the value of each column becomes clear.The binary number system works in the exact same way as the decimal system, except that it contains only two digits, 0 and 1. Start counting in binary: 0, 1, Oops! There are no more binary digits. In order to keep counting, we need to add a second column worth?twice?the value of the column before. We continue counting again: 10, 11, Oops! It is time to add another column again. Counting further: 100, 101, 110, 111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111.... Watch the pattern of 1's and 0's. You will see that binary works the same way decimal does, but with fewer digits.Binary uses two digits, so each column is worth twice the one before. This fact, coupled with expanded notation, can be used convert between from binary to decimal. In the binary system, the columns are worth 1, 2, 4, 8, 16, 32, 64, 128, 256, etc. To convert a number from binary to decimal, simply write it in expanded notation. For example, the binary number 101101 can be rewritten in expanded notation as 1×32 + 0×16 + 1×8 + 1×4 + 0×2 + 1×1. By simplifying this expression, you can see that the binary number 101101 is equal to the decimal number 45.An easy way to convert back and forth from binary to decimal is to use Microsoft Windows Calculator. You can find this program in the Accessories menu of your Start Menu. To perform the conversion, you must first place the calculator in scientific mode by clicking on the View menu and selecting Scientific mode. Then, enter the decimal number you want to convert and click on the "Bin" check box to convert it into binary. To convert numbers from binary to decimal, click on the "Bin" check box to put the calculator in binary mode, enter the number, and click the "Dec" check box to put the calculator back in decimal mode.How Hexadecimal WorksBinary is an effective number system for computers because it is easy to implement with digital electronics. It is inefficient for humans to use binary, however, because it requires so many digits to represent a number. The number 76, for example, takes only two digits to write in decimal, yet takes seven digits to write in binary (1001100). To overcome this limitation, the?hexadecimal number system was developed. Hexadecimal is more compact than binary but is still based on the digital nature of computers.Hexadecimal works in the same way as binary and decimal, but it uses sixteen digits instead of two or ten. Since the western alphabet contains only ten digits, hexadecimal uses the letters A-F to represent the digits ten through fifteen. Here are the digits used in hexadecimal and their equivalents in binary and decimal:Hex0123456789ABCDEFDecimal0123456789101112131415Binary0000000100100011010001010110011110001001101010111100110111101111Let's count in hexadecimal. Starting from zero, we count 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F. At this point there are no more digits, so we add another column. Continue counting: 10, 11, 12, 13, 14, 15, 16, 17 18, 19, 1A, 1B, 1C, 1D, 1E, 1F. Once again, we are out of digits in the first column, so we add one to the next column. Continue counting once again: 20, 21, 22, ..., 29, 2A, 2B, 2D, 2E, 2F, 30, 31, 32, ..., 3E, 3F, 40, 41, 42, ... 99, 9A, 9B, 9C, 9D, 9E, 9F, A0, A1, A2, ... F9, FA, FB, FC, FD, FE, FF, 100, 101, 102, .... Watch the pattern of numbers and try to relate this to the way you count in decimal or binary. You will see that it is the same procedure, but with sixteen digits instead of 10 or 2.Each column in hexadecimal is worth 16 times the column before, while each column in binary is worth 2 times the column before. Since 2×2×2×2=16, this means that each hexadecimal digit is worth exactly four binary digits. This fact makes it easy to convert between binary and hexadecimal.To convert from hexadecimal to binary, simply look at the chart above and replace each digit in the hexadecimal number with its corresponding four-digit binary number. For example, 8F in hexadecimal is 10001111 in binary, since 8=1000 and F=1111.To converty from binary to hexadecimal, reverse the procedure and break the binary number into blocks of four digits. Then, replace each block of four digits with its corresponding hexadecimal digit. If you cannot divide the binary number evenly into blocks of four digits, add zeros to the left side of the number to make it work. For example, to convert 110101 to hexadecimal, first add two zeros at the beginning of the number to make it 00110101. Since 00110101 has eight digits, it can be divided into two blocks of four digits, 0011 and 0101. Since 0011=3 and 0101=5, the corresponding hexadecimal number is 35.Octal NumbersThe?octal? HYPERLINK "; \o "Numeral system" numeral system, or?oct?for short, is the? HYPERLINK "; \o "Radix" base-8 number system, and uses the digits 0 to 7. Octal numerals can be made from? HYPERLINK "; \o "Binary numeral system" binary?numerals by grouping consecutive binary digits into groups of three (starting from the right). For example, the binary representation for decimal 74 is 1001010, which can be grouped into (00)1 001 010 – so the octal representation is 112.In the decimal system each decimal place is a power of ten. For example:In the octal system each place is a power of eight. For example:By performing the calculation above in the familiar decimal system we see why 112 in octal is equal to 64+8+2 = 74 in decimal.Operators.An operator is a symbol which helps the user to command the? HYPERLINK "; \t "_blank" \o "Computer" Computer?to do a certain mathematical or logical manipulations. In mathematics and sometimes in computer programming, an operator is a? HYPERLINK "; character?that represents an action, as for example?x?is an arithmetic operator that represents multiplication. In computer programs, one of the most familiar sets of operators, the HYPERLINK "; Boolean?operators, is used to work with true/false values. Boolean operators include AND, OR, NOT (or AND NOT), and NEAR. These (and variations such as XOR) are used in? HYPERLINK "; logic gate?s. You may have used Boolean operators in a? HYPERLINK "; search engine?, by entering a phrase such as? HYPERLINK "; Galileo?AND satellite?(some search engines require the operator be capitalized) to find information. Among the other types of operators used in computer programming are: assignment operators?, which assign a specified value to another value and?relational operators?, which compare two values.Logical OperationsLogical AND (&&) :?This operator is used to evaluate 2 conditions or expressions with relational operators simultaneously. If both the expressions to the left and to the right of the logical operator is true then the whole compound expression is true.?Example :?a > b && x = = 10The expression to the left is a > b and that on the right is x == 10 the whole expression is true only if both expressions are true i.e., if a is greater than b and x is equal to 10.?Logical OR (||) :?The logical OR is used to combine 2 expressions or the condition evaluates to true if any one of the 2 expressions is true.?Example :?a < m || a < nThe expression evaluates to true if any one of them is true or if both of them are true. It evaluates to true if a is less than either m or n and when ais less than both m and n.?Logical NOT (!) :?The logical not operator takes single expression and evaluates to true if the expression is false and evaluates to false if the expression is true. In other words it just reverses the value of the expression.?For example :?! (x >= y)The NOT expression evaluates to true only if the value of x is neither greater than or equal to y.Software package?-Written programs or procedures or rules and associated documentation pertaining to the operation of a computer system and that are stored on disks.HypermediaHypermedia is used as a logical extension of the term hypertext, in which graphics, audio, video, plain text and hyperlinks intertwine to create a generally nonlinear medium of information. This contrasts with the broader term multimedia, which may be used to describe non-interactive linear presentations as well as hypermedia.The World Wide Web is a classic example of hypermedia, whereas a non interactivecinema presentation is an example of standard multimedia due to the absence of hyperlinks. Most modern hypermedia is delivered via electronic pages from a varietyof systems. Audio hypermedia is emerging with voice command devices and voice browsing.World Wide Web?The?World Wide Web?(abbreviated as?WWW?or?W3?commonly known as?the Web), is a? HYPERLINK "; \o "Information system" system?of interlinked? HYPERLINK "; \o "Hypertext" hypertext documents accessed via the? HYPERLINK "; \o "Internet" Internet. With a? HYPERLINK "; \o "Web browser" web browser, one can view? HYPERLINK "; \o "Web page" web pages?that may contain text, images, videos, and other HYPERLINK "; \o "Multimedia" multimedia, and? HYPERLINK "; \o "Web navigation" navigate?between them via? HYPERLINK "; \o "Hyperlink" hyperlinks.The terms Internet and World Wide Web are often used in everyday speech without much distinction. However, the Internet and the World Wide Web are not one and the same. The Internet is a global system of interconnected? HYPERLINK "; \o "Computer networks" computer networks. In contrast, the Web is one of the services that runs on the Internet. It is a collection of text documents and other resources, linked by hyperlinks and URLs, usually accessed by? HYPERLINK "; \o "Web browsers" web browsers?from? HYPERLINK "; \o "Web servers" web servers. In short, the Web can be thought of as an? HYPERLINK "; \o "Application software" application?"running" on the Internet. Viewing a? HYPERLINK "; \o "Web page" web page?on the World Wide Web normally begins either by typing the? HYPERLINK "; \o "Uniform Resource Locator" URL?of the page into a? HYPERLINK "; \o "Web browser" web browser?or by following a? HYPERLINK "; \o "Hyperlink" hyperlink?to that page or resource. The web browser then initiates a series of communication messages, behind the scenes, in order to fetch and display it. As an example, consider accessing a page with the URL, the browser resolves the server-name portion of the URL () into an? HYPERLINK "; \o "IP address" Internet Protocol address?using the globally distributed database known as the? HYPERLINK "; \o "Domain Name System" Domain Name System?(DNS); this lookup returns an IP address such as?208.80.152.2. The browser then requests the resource by sending an? HYPERLINK "; \o "Hypertext Transfer Protocol" HTTP?request across the Internet to the computer at that particular address. It makes the request to a particular application port in the underlying? HYPERLINK "; \o "Internet Protocol Suite" Internet Protocol Suite?so that the computer receiving the request can distinguish an HTTP request from other network protocols it may be servicing such as e-mail delivery; the HTTP protocol normally uses? HYPERLINK "; \o "List of TCP and UDP port numbers" port 80. The content of the HTTP request can be as simple as the two lines of ponents of World Wide WebThere are essentially three components which together form the World Wide Web, the medium which has brought this document to your screen. They are the HYPERLINK "; \l "INTER" Internet, the HYPERLINK "; \l "SERVE" Information Servers which contain and dispense information, and the HYPERLINK "; \l "BROWS" Web Browser which the individual uses to obtain information and pages from the web. This page briefly describes each of these components.The quick explanation of the web is this: HYPERLINK "; \l "BROWS" web browsers use the HYPERLINK "; \l "INTER" Internet to access HYPERLINK "; \l "SERVE" Servers that contain the pages, images, and other files that the web user is interested in receiving. The Internet The Internet, on the technological level, consists of the wires, cables, machines, and networking software which connect millions of computers around the world. This complex infrastructure of computer networks is the pavement of the "Information Superhighway" that allows web browsers to communicate with servers, request, send, and receive information from around the world, regardless of global rmation Servers Information HYPERLINK "; servers run on computers connected to the Internet all over the world. Information servers are processes (executing computer software) which dish out information as requested from users connected to the same network (in the case of the WWW, the public Internet). The most common information types of servers on the Internet today are: World Wide Web servers; Also called http servers for the underlying protocol with which they communicate with Web HYPERLINK "; browsers, the HyperText Transport Protocol. These servers primarily deliver data for immediate human consumption, primarily web pages. HYPERLINK "; WebCom allows people to have their own websites by giving people the abiliity to create pages that are served by WebCom's World Wide Web servers. See also: HYPERLINK "; hypertext and HYPERLINK "; multimedia. Gopher servers; The immediate predecessors of World Wide Web servers, gopher servers present files in distributed archives to you as hierarchical menus. Using a gopher HYPERLINK "; client, you would select a file from a menu. If that file were text, it would next appear on your screen for you to read or browse. If it were any other form of data, such as an image, the file would be transferred to your local computer where you would have to use a separate program to view or use it. After you were done reading or downloading a file, a gopher client would always return you to the previous menu from which you had selected the file. FTP, or File Transport Protocol Servers; Whose only function is to allow HYPERLINK "; FTP clients to copy files of any kind (programs, images, text, etc.) between the client and server machines. FTP allows you to enter commands and filenames to send to, receive from, and otherwise manage files and directories on a remote computer. (If you log in to read files other than your own, you have to log in as "anonymous" or "ftp", which allows you to read all public files but not alter or delete them, or create new ones.) When you retrieve a file from a remote computer using FTP, you have to invoke a separate program after your FTP session to view that file (a text editor, an image viewer, etc.). WebCom customers use FTP to maintain their WebCom file directories. Graphical FTP clients for Windows or Macintosh relieve the user of the need to learn most of the FTP commands, allowing the user instead to simply drag and drop files to and from their WebCom directory as though it were a local drive on their machine. NNTP, or Network News Transport Protocol servers; Which deliver Usenet newsgroups and articles. SMTP, Simple Mail Transport Protocol servers; Which send and receive electronic mail messages. Archie; Which searches indices of FTP archives for files when given a file name or name fragment. Veronica; Which searches gopher menus for words or phrases. Telnet servers; Which allow you to login and conduct a terminal session on the remote computer running the server from anywhere on the net. These sessions are normally UNIX terminal sessions conducted via "VT100" terminal emulators - programs that allow your computer to emulate a DEC VT100 terminal to the remote host. WAIS, Wide Area Information Servers; Which search distributed volumes of text (which have been pre-indexed for this purpose) for words and phrases, and rank results based on a score - how closely each document satisfied the search criterion. In the past, accessing these servers required using a separate program for each server type. To access a gopher server, you had to run a gopher client program. To access an FTP server, you had to run your FTP client. To search for a file using Archie or Veronica, you had to run either an Archie or a Veronica client. Web Browsers The third component of the World Wide Web, a new generation of Internet information HYPERLINK "; clients called Web Browsers, such as HYPERLINK "; Mosaic and HYPERLINK "; Lynx have recently been developed. These browsers have three new capabilities which revolutionize searching and browsing the Internet: World Wide Web browsers are multilingual; they can communicate with all of the servers listed above and more. This relieves the user of the complexities of having to learn and run a separate client for each server they wish to use. There is still some value to understanding the functionality of the underlying servers, however this is less of a requirement when using a WWW browser. Also, for some of these servers it is often more convenient to use a specialized client, such as a HYPERLINK "; threaded news reader to read Usenet news, an Email program to send and receive Email messages, or an FTP client when, for instance, you want to send a file from your computer to a remote computer, or you want to retrieve a large number of files in one bulk copy operation. World Wide Web browsers employ a graphical user interface. Many of the above servers require you to learn an arcane command language or enter UNIX commands. With a WWW browser, you just use your mouse or arrow keys to point at what you want, and click or press return. The browser takes care of the underlying network communications, interfaces, and commands, to bring to you what you clicked on. WWW browsers allow the free-form organization and cross linking and referencing of information called hypertext, hypermedia, or hyperlinking. In this form of information organization, any item of information (a word, a phrase, an image) can also function as a " HYPERLINK "; hotlink" to any other item of information. Underneath every hotlink, hidden to the reader, is a URL, or Uniform Resource Locator, which tells your browser where to find the resource pointed to by that hotlink; all you do is point and click. Furthermore, anybody can create hotlinks in their documents to any other publicly accessible resource (you can create hotlinks to your own resources or anybody elses, and anybody else can create hotlinks to your information). This structure creates freedom to organize and share information in myriad and novel ways, resulting in an anarchic, loosely structured web of information, art, music, data, software, literature, and just about anything else which can be represented in digital form and which some person or organization has a desire to share with the world. This is the World Wide Web. As World Wide Web browsers greatly simplify the browsing and retrieval information from the Web, we at HYPERLINK "; WebCom aim to greatly simplify your ability to be a provider of information and services on the Web.Word Processing Word Processing is using a computer to create, edit, and print documents. Of all computer applications, word processing is the most common software packages. To perform word processing, you need a computer, a special program called a word processor, and a printer. A word processor enables you to create a document, store it electronically on a disk, display it on a screen, modify it by entering commands and characters from the keyboard, and print it on a printer. The great advantage of word processing over using a typewriter is that you can make changes without retyping the entire document. If you make a typing mistake, you simply back up the HYPERLINK "; cursor and correct your mistake. If you want to HYPERLINK "; delete a paragraph, you simply remove it, without leaving a trace. It is equally easy to HYPERLINK "; insert a word, sentence, or paragraph in the middle of a document. Word processors also make it easy to move sections of HYPERLINK "; text from one place to another within a document, or between documents. When you have made all the changes you want, you can send the HYPERLINK "; file to a printer to get a hardcopy. Using word processing software is an efficient way of storing documents because many documents can be stored on a disk. One of the benefits of word processing software is the ability to print the same document many times, with each copy looking just like the firstWord processors vary considerably, but all word processors HYPERLINK "; support the following basic HYPERLINK "; features: insert text: Allows you to insert text anywhere in the document. delete text: Allows you to erase characters, words, lines, or HYPERLINK "; pages as easily as you can cross them out on paper. HYPERLINK "; cut and HYPERLINK "; paste : Allows you to remove ( HYPERLINK "; cut) a section of text from one place in a document and insert ( HYPERLINK "; paste) it somewhere else. HYPERLINK "; copy : Allows you to duplicate a section of text. page size and HYPERLINK "; margins : Allows you to define various page sizes and margins, and the word processor will automatically readjust the text so that it fits. scrolling: is the process of moving different portions of a document on the screen into view. HYPERLINK "; search and replace : Allows you to direct the word processor to search for a particular word or phrase. You can also direct the word processor to HYPERLINK "; replace one group of characters with another everywhere that the first group appears. HYPERLINK "; word wrap : The word processor automatically moves to the next line when you have filled one line with text, and it will readjust text if you change the margins. Word wrap allows you to type words in a paragraph without pressing the ENTER key at the end of each line. Note: Microsoft considers you create a paragraph every time you pressed the ENTER key. To create a paragraph in Word 2007, press the ENTER key. print: Allows you to send a document to a printer to get hardcopy. The Ribbon is the control center in Word 2007. The Home Tab, called the primary tab, contains the more frequently used commands. Contextual tabs display when certain objects like table or pictures are selected.6. Word processors that support only basic word processing features (and maybe a few others) are called HYPERLINK "; text editors. Most word processors, however, support additional features that enable you to manipulate and HYPERLINK "; format documents in more sophisticated ways. These more advanced word processors are sometimes called full-featured word processors. Microsoft Word 2007 is a full featured word processing program. Full-featured word processors usually support the following features: HYPERLINK "; file management : Many word processors contain file management capabilities that allow you to create, delete, move, and search for files. HYPERLINK "; font styles: Allows you to change fonts within a document. For example, you can specify HYPERLINK "; bold, italics, and underlining. Most word processors also let you change the font size and even the HYPERLINK "; typeface. There are two types of typeface serif fonts, such as Times New Roman and sans-serif fonts such as Arial and Impact. Serif fonts are good for paragraphs because the extensions guide your eyes as you read the paragraph. Sans-serif fonts are good for titles and headings. footnotes and cross-references: Automates the numbering and placement of footnotes and enables you to easily cross-reference other sections of the document. graphics: Allows you to embed illustrations and graphs into a document. Some word processors let you create the illustrations within the word processor; others let you insert an illustration produced by a different program. HYPERLINK "; headers , HYPERLINK "; footers , and page numbering: Allows you to specify customized headers and footers that the word processor will put at the top and bottom of every page. The word processor automatically keeps track of page numbers so that the correct number appears on each page. HYPERLINK "; layout : Allows you to specify different margins within a single document and to specify various methods for indenting paragraphs. Search: feature, in combination with the replace feature, allows users of word processing software to substitute existing characters or words with new ones HYPERLINK "; spell checker : A HYPERLINK "; utility that allows you to check the spelling of words. It will HYPERLINK "; highlight any words that it does not recognize. tables of contents and indexes: Allows you to automatically create a table of contents and index based on special codes that you insert in the document. thesaurus: A built-in thesaurus that allows you to search for synonyms without leaving the word processor. HYPERLINK "; windows : Allows you to edit two or more documents at the same time. Each document appears in a separate HYPERLINK "; window. This is particularly valuable when working on a large project that consists of several different files. HYPERLINK "; WYSIWYG (what you see is what you get): is the capability to display a document on the display screen exactly as it will look when printed.The height of a character is measured in points. A point is about 1/72 of one inch in height. A character with a font size of 12 is 12/72 or 1/6 of one inch in height. On most computers the default font size is 12. A formatting character or a nonprinting character is a character that displays on the screen but is not visible on a printed document.As you create a document in Word, the computer stores it in RAM or memory. Before you save a document, it is stored in RAM. If you turn off the computer or if you lose electrical power, the document in memory is lost. When producing a document using word processing software, the document should be saved frequently so work will not be lost. Saving is the process of copying a document from memory to a storage medium such as a floppy disk or hard drive. When you save a document in Word, you can give it a filename that has up to 255 characters, including spaces. The only invalid characters are: \ / < > : * ? “ | Word contains a series of predefined graphics called clip art that you can insert into a Word document. A header is text you want that prints at the top of each page. Footer is text that prints at the bottom of each page. AutoCorrect is a feature that automatically corrects common spelling errors as you type. Word indicates a possible spelling error with a wavy red underline. Word indicates a possible grammatical error with a wavy green underline. Copy and Paste is a very powerful command. If you want to copy a selection of text, you would click the copy button. There are two types of page break. A soft page break is automatically created when the text exceeds the capacity of the page. A hard page break is inserted by the user to start a new page. To save a document in a different format or with a different name, click the Office Button and select Save as. Word 2007 can be used to create Internet web pages, high quality memos, forms and resumes. To convert your document to a web page in Word 2007, you would select the Save as Web page on the File menu. Editing is the process of making changes to the document’s content. A hyperlink is a shortcut that allows you to jump to Another documentAnother document on your networka page on the world wide web To print a specific page of a multi-page document, use the print command under the Office button window menu. For example to print page 3 and pages 5 – 10 you would specify 3, 5 – 10 in the print dialogue box. There are 2 printing orientations: portrait and landscape. In portrait orientation the page is taller than it is wider. In landscape orientation the paper is wider than it is taller. Portrait is used for letters, memos and most documents. Landscape is normally used when the page has a table to wide to print in portrait orientation. Print Screen copies the image on the screen to the clipboard. Alt-Print Screen copies the active window to the clipboard. The content of the clipboard is cleared when the content is replaced or when the computer is turned off. Office Clipboard can hold up to 24 items. The Windows clipboard can only hold one item. Font styles include bold, italicize and underline. When a program is run, a copy of the program is loaded from secondary storage (hard disk or floppy) to RAM. To move text in a document, you could use cut and paste or drag and drop. Keyboard Shortcuts:Ctrl-C CopyCtrl-X CutCtrl-V PasteCtrl-Z UndoCtrl-Y Redo/RepeatCtrl-A Select AllCtrl-F FindCtrl-H Replace A template is a document that contains the formatting necessary for a specific document type Metadata is defined as data about data. HYPERLINK "; ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?Spreadsheets Spreadsheet:?A grid of rows and columns containing numbers and text that allows the user to manage, predict, and present information. An electronic spreadsheet is a computer application program that can also hold formulas in a cell that serve as a calculator. These formulas allow the electronic spreadsheet to perform calculations much faster and more accurately that spreadsheets created with pencil, paper, and calculator. An electronic spreadsheet is a computer application program that can also hold formulas in a cell that serve as a calculator. These formulas allow the electronic spreadsheet to perform calculations much faster and more accurately that spreadsheets created with pencil, paper, and calculator.?Formula Bar:?Appears directly below the toolbar on the spreadsheet. On the far left side of the Formula Bar is the cell reference box that identifies the active cell.Row:?Horizontal lines of data across the spreadsheet that are identified by numbers on the left side of the spreadsheet window.Cell:?The intersection of a row and a column on a spreadsheet that is identified by a cell reference, the column letter and the row number (C2, E8, D1).Column:?Vertical lines of data in a spreadsheet that are identified by letters at the top of the spreadsheet window. (A, B, C, AB, AC, AD....).Range:?A selected group of cells that touch each other and form a rectangle. Operations can be performed on a range of cell.; A defined block of cells on a spreadsheet.Enter:?type in or record data in a spreadsheet.Label:?text symbols, dates or numbers(not used in calculations).Values:?a number that is entered on a spreadsheet and used for calculations.Edit:?to change the original entry in a spreadsheet.Formula:?Arthmetic equation with symbols(+-*/) for mathematical operations: A3+B3-C3*4Function:?Functions create shortcut formulas for the user: Sum (auto addition) and Avg (auto averaging of numbers).; A special formula that does not use operators to calculate a resultOperand:?a number, cell reference, or field name used in a calculation in the formulas of spreadsheets or databases; in a database the operands are field names.Operator: Tells Works what to do with the operands in a formula.Order of Operation:?The sequence used to calculate the value of a formula.Order of? OperationsParenthesis?Exponents ^Multiplication *Division /Addition +Subtraction -Relative Cell Reference:?A cell reference that adjusts to a new location when copied or moved.Absolute Cell Reference:?A cell reference that does not adjust to the new cell location when copied or movedMixed Cell Reference:?A cell reference containing both relative and absolute referencesAdvantages of Computer Spreadsheet:Can answer, "What is? " (determines current information)Students current gradeIndividual athlete statisticsTransportation scheduleCurrent $ available for spendingCensus resultsCan answer "What if?" (predicts future events/information)Student population increasesWin/loss record changesProduct sales decrease-hourly wage rate changesUS immigration rate increasesVarious Uses for SpreadsheetsSchool: student grades, payroll, future budgets, class sizes, and schedulesSports: individual and team statistics current and future budgetPersonal: checkbook, household expenses, investments, income taxesBusiness: payroll, investments, inventory, product sales and deliveryGovernment: taxes, census, loans, investments, budgetsChartsCharts illustrate dataCharts can be created from spreadsheetThree types of charts are:BARLINEPIEBar ChartUsed to compare individual or sets of values to each other.The height of each bar being proportional to its corresponding value.Uses rectangles of varying height to illustrate values in a spreadsheet.Pie ChartUsed to show relationship of one set of data to the entire data.The size of each wedge represents the percentage that each value adds to the Total.Show the relationship of a part to a whole.Each part is presented as a "slice" of pie.Scatter ChartSometimes called XY chartsShow the relationship between two categories of data.One category is represented on the vertical axis and the other category is represented on the horizontal axis.The result is a "cloud" of data points that may or may not have a recognizable shape.It is not practical to connect the data points with a line because points on a scatter chart usually do not relate to each other.Line ChartUsed to show trends since the lines connect points of data.Used to show changes over a period of time.Similar to the bar chart except bars are replaced by points connected by a line.Steps to create a chartHighlight the data to be charted.Determine the chart typeEnhance the chart with titles?A?computer network, often simply referred to as a network, is a collection of? HYPERLINK "; \o "Computers" computers?and devices interconnected by communications channels that facilitate communications and allow sharing of resources and information among interconnected devices.?Computer networking?or?Data communications?(Datacom) is the? HYPERLINK "; \o "Engineering" engineering? HYPERLINK "; \o "Discipline" discipline?concerned with the computer networks. Computer networking is sometimes considered a sub-discipline of? HYPERLINK "; \o "Electrical engineering" electrical engineering,? HYPERLINK "; \o "Telecommunications" telecommunications,? HYPERLINK "; \o "Computer science" computer science,? HYPERLINK "; \o "Information technology" information technology?and/or computer engineering?since it relies heavily upon the theoretical and practical application of these scientific and engineering disciplines.PurposeComputer networks can be used for a variety of purposes:Facilitate communications.?Using a network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.Sharing of hardware.? In a networked environment, each computer on a network may access and use hardware resources on the network, such as printing a document on a shared network printerSharing of files, data, and information. In a network environment, authorized user may access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks.Sharing software. Users connected to a network may run application? HYPERLINK "; \o "Computer program" programs?on remote ponent of a network:At least two computers Server or Client working Interface Card's (NIC)A connection medium, usually a wire or cable, although wireless communication between networked computers and peripherals is also work Operating system software, such as Microsoft Windows servers, Novell NetWare, Unix and Linux.Types of Networks:LANs (Local Area Networks)LAN network is any collection of independent computers that communicate with one another over a shared network medium. LANs are networks usually confined to a geographic area, such as a single building or a college campus. LANs can be small, linking as few as three computers, but often link hundreds of computers used by thousands of people. The development of standard networking protocols and media has resulted in worldwide proliferation of LANs throughout business and educational organizations.WANs (Wide Area Networks)Wide area networking combines multiple LANs that are geographically separate. This is accomplished by connecting the different LANs using services such as dedicated leased phone lines, dial-up phone lines (both synchronous and asynchronous), satellite links, and data packet carrier services. Wide area networking can be as simple as a modem and remote access server for employees to dial into, or it can be as complex as hundreds of branch offices globally linked using special routing protocols and filters to minimize the expense of sending data sent over vast distances.InternetThe Internet is a system of linked networks that are worldwide in scope and facilitate data communication services such as remote login, file transfer, electronic mail, the World Wide Web and newsgroups.With the meteoric rise in demand for connectivity, the Internet has become a communications highway for millions of users. The Internet was initially restricted to military and academic institutions, but now it is a full-fledged conduit for any and all forms of information and commerce. Internet websites now provide personal, educational, political and economic resources to every corner of the planet.IntranetWith the advancements made in browser-based software for the Internet, many private organizations are implementing intranets. An intranet is a private network utilizing Internet-type tools, but available only within that organization. For large organizations, an intranet provides an easy access mode to corporate information for employees.MANs (Metropolitan area Networks)The refers to a network of computers with in a City.VPN (Virtual Private Network)VPN uses a technique known as tunneling to transfer data securely on the Internet to a remote access server on your workplace network. Using a VPN helps you save money by using the public Internet instead of making long–distance phone calls to connect securely with your private network. There are two ways to create a VPN connection, by dialing an Internet service provider (ISP), or connecting directly to Internet. ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download