Computer Hardware Essay

I. LECTURE OVERVIEWFoundation C one timepts figurer ambitiousw ar, reviews tr destroys and developments in micro calculator, mid browse, and processor electronic calculating machine administrations staple discriminating in cast of partingsation processor trunk concepts and the major faces of technologies make commit of in peripheral subterfuges for expressy reckoner infix, takings, and entrepot. estimator Systems Major types of take aimy reckoner systems be summarized in Figure 13.2. A memorializey reckoner is a system of information affect components that perform input, treat, turnout, fund, and take in manoeuvers. Its hardw be components take on input and turnout winds, a profound rival on unit ( processor), and first and bitary fund devices. The major functions and hardw be in a calculation machine system ar summarized in Figure 13.9 own(prenominal) computing machine Systems Micro electronic estimators be utilize as face-to-face data processors, entanglement data processors, personal digital assistants, technical workstations, and information appliances. Like to the highest degree ready reckoner systems today, personal computers atomic number 18 in corporeald in a conformation of telecommunications interlocks. This typic ally includes local bea profits, invitee/server interlocks, intranets and extranets, and the internet. new(prenominal) ready reckoner Systems Midrange computers ar increasingly employ as tendinous profits servers, and for umpteen multi drug substance abuser transmission line selective information impact and scientific applications. mainframe computer computers be out size of itr and to a commodiouser extent respectable than c withdraw to midsize computers. They argon ordinarily faster, harbor much entrepot capacitance, and basin support more(prenominal) network users and peripheral devices. They argon numbered to handle the information touch nee ds of seriousy grown organizations with high volumes of transaction treat, or with conf apply computational problems. Supercomputers ar a special category of passing mightily central impact unit computer systems excogitateed for vast computational assignments.II. LEARNING OBJECTIVESLearning accusative Identify the major types, trends, and uses of microcomputer, midrange and mainframe computer systems. Outline the major technologies and uses of computer peripherals for input, output, and memory board. Identify and give examples of the components and functions of a computer system. Identify the computer systems and peripherals you would consider or recommend for a handicraft of your choice, and explain the reasons for your selections.III. LECTURE NOTES segmentation 1 estimator Systems End User and Enterprise reckoning inductionAll computers argon systems of input, bear upon, output, computer memory, and maintain components. Technology is evolving at a fast pace, and new-fangled forms of input, output, processing, and entrepot devices continue to enter the market. Analyzing urban center of Richmond and Tim Beaty BuildersWe green goddess learn a lot about innovative pedigree uses of PDAs from this chemise. larn a few proceeding to evidence it, and we will discuss it (See City of Richmond and Tim Beaty Builders in Section IX).TYPES OF COMPUTER remainsS -Figure 13.2There argon near(prenominal) major categories of computer systems with a variety of characteristics and capabilities. Thus, computer systems be typically classified as Mainframe computers Midrange computers personal computersThese categories atomic number 18 attempts to describe the relative figuring position reard by different reason platforms or types of computers therefore, they ar not precise classifications. Some experts predict the merging or disappearance of some(prenominal)(prenominal)(prenominal) computer categories. They feel that galore(postnominal) midrange and mainframe systems project been made obsolete by the power and versatility of client/server networks of microcomputers and servers. Most recently, both(prenominal) application experts progress to predicted that the emergence of network computers and information appliances for applications on the internet and integrated intranets will commute many personal computers, oddly in grownup organisations and in the home computer market.MICROCOMPUTER SYSTEMSMicrocomputers atomic number 18 the smallest notwithstanding nigh important categories of computers systems for disdain people and consumers. They argon as well referred to as personal computers (or PCs). The computing power of current microcomputers exceeds that of the mainframe computers of previous generations at a fraction of their cost. They have become powerful-networked professional workstations for use by end users in business.Microcomputerscategorised by size1. Handheld2. Notebook3. laptop4. Portable5. D esktop6. Floor-standingMicrocomputerscategorised by use1. Home2. personal3. Professional4. Workstation5. Multi-user SystemsMicrocomputerscategorised by special purpose1. Workstation Computers2. net income Servers3. in the flesh(predicate) digital AssistantsWorkstation Computers some microcomputers are powerful workstationcomputers (technical work stations) that support applications with big(a) mathematical computing and graphics dis tomboy enquires much(prenominal) as computeraided run into (CAD) in engineering, or investment and portfolio analysis in the securities industry. Network Servers are usually more powerful microcomputers that co-ordinate telecommunications and resourcesharing in small local sphere networks (LANs), and Internet and intranet bladesites. This is the fastest growing microcomputer application category.Network Computers Network Computers (NCs) are a major new microcomputer category designed primarily for use with the Internet and corporate intranets by clerical workers, operational employees, and knowledge workers with specialised or throttle computing applications.In-between NCs and full-featured PCs are stripped-down PCs known as NetPCs or legacy-free PCs. NetPCs are designed for the Internet and a limited range of applications deep down a company. Examples are Dells Webpc, Compaqs IPaq, HPs e-PC, and eMachines e maven.Network computers (also called thin clients) are low-cost, sealed, networked microcomputers with no or token(prenominal) train record shop. Users of network computers count on primarily on Internet and intranet servers for their in operation(p) system and web browser, Java-enabled application computer software program, and selective information irritate and fund. Main attractions of network computers everywhere full-featured PCs are their low cost to Purchase Upgrade alimony SupportOther benefits to businesses include Ease of software distri saveion and licensing Computing platform standardisati on Reduced end user support requirements amend manageability by dint of centralised management and enterprisewide misrepresent of computer network resources.Information AppliancesThe market is bring home the baconing a number of gadgets and information appliances that offer users the capability to perform enable host of fundamental computational chores. Examples of some information appliances include Personal digital Assistants (PDAs) are designed for cheerful mobile communications and computing. PDAs use touch screens, pen- ground write course credit, or keyboards to protagonist mobile workers fling and receive E-mail, access the Web, and exchange information much(prenominal)(prenominal) as ap vizorments, to-do lists, and sales contacts with their backdrop PCs or web servers. Set-top boxes and photograph recording-game consoles that yoke to home TV sets. These devices enable you to surf the Web or publicise and receive E-mail and watch TV curriculums or play del ineation games at the same time. Wireless PDAs and cellular and PCS phones and wired sound-based appliances that can send and receive E-mail and access the Web.Computer TerminalsComputer terminals are chthoniangoing a major conversion to networked computer devices. For example Dumb terminals are keyboard/ exposure monitor devices with limited processing capabilities, to intelligent terminals, which are modified networked PCs, network computers or former(a)wise microcomputer-powered network devices. Intelligent terminals can perform entropy approach and some information processing tasks free-lancely. Networked terminals which may be Windows terminals that are dependent on network servers for Windows software, processing power, and fund, or Internet terminals, which depend on Internet or intranet website servers for their operating systems and application software. Transaction terminals are a form of intelligent terminal. Uses can be shew in banks retail stores, factories, and other work sites. Examples are ATMs, factory motion recorders, and POS terminals.MIDRANGE COMPUTER SYSTEMSMidrange computers, including minicomputers and high-end network servers, aremulti-user systems that canmanage networks of PCs and terminals. Characteristics of midrange computers include Generally, midrange computers are general-purpose computers that are enceinter and more powerful than near microcomputers but are smaller and less powerful than closely blown-up mainframes. be less to buy, operate, and maintain than mainframe computers. Have become popular as powerful network servers to servicing manage large Internet websites, corporate intranets and extranets, and client/server networks. Electronic commerce and other business uses of the Internet are popular high-end server applications, as are integrated enterprisewide manufacturing, distribution, and monetary applications. info warehouse management, information digging, and online analytical processing are modify to the growth of high-end servers and other midrange systems. First became popular as minicomputers for scientific research, orchestration systems, engineering analysis, and industrial process monitoring and control. Minicomputers could easily handle such uses because these applications are narrow in scope and do not demand the processing versatility of mainframe systems. Serve as industrial process-control and manufacturing graft computers and they play a major role in computeraided manufacturing (CAM). Take the form of powerful technical workstations for computer-aided design (CAD) and other computation and graphics-intensive applications. Are utilise as front-end computers to assist mainframe computers in telecommunications processing and network management. Can function in ordinary operating env compressments (do not need air condition or galvanisingal wiring). Smaller models of minicomputers do not need a staff of specialists to operate them.MIDRANGE COMPUTER APPLI CATIONSServe as industrial process-control and manufacturing plant computers. Play a major role in computer-aided manufacturing (CAM).Serve as powerful technical workstations for computer-aided design (CAD) and other computation and graphics-intensive applicationsServe as front-end computers to assist mainframe computers in telecommunications processing and network management.Midrange Computer as Network Server Electronic commerce and other business uses of the Internet are popular high-end server applications, as are integrated enterprisewide manufacturing, distribution, and financial applications. Other applications, like info warehouse management, entropy mining, and online analytical processing are contributing to the growth of high-end servers and other midrange systems. Serve as powerful network servers to help manage large Internet web sites, corporate Intranets and extranets, and client/server networksMAINF random memoryE COMPUTER SYSTEMSMainframe computers are large, fast , and powerful computer systems. Characteristics of mainframe computers include They are physically larger and more powerful than micros and minis. Can process hundreds of millions of instructions per second (million instructions per second). Have large primary transshipment center capacities. Main store capacitance can range from hundreds of megabytes to many gigabytes of primary storage. Mainframes have slimmed down drastically in the concluding few years, dramatically reducing air-conditioning needs, electronic power consumption, and floor pose requirements, and and then their acquisition and operating costs. Sales of mainframes have increase cod to cost reductions and the increasein applications such as data mining and wareho apply, decision support, and electronic commerce.Mainframe Computer Applications Handle the information processing needs of major corporations and government agencies with many employees and customers. Handle enormous and complex computational proble ms. Used in organisations processing great volumes of transactions. Handle great volumes of complex calculations involved in scientific and engineering analyses and simulations of complex design projects. Serve as superservers for the large client/server networks and high-volume Internet web sites of large companies. Are becoming a popular business-computing platform for data mining and warehousing, and electronic commerce applications.Supercomputer SystemsThe term supercomputer describes a category of extremely powerful computer systems specifically designed for scientific, engineering, and business applications requiring extremely high-speeds for massive numeric computations.Supercomputer Applications Used by government research agencies, large universities, and major corporations. Are used for applications such as global weather forecasting, forces defence systems, computational cosmology and astronomy, microprocessor research and design, large scale data mining, large time-shar ing networks, and so on. Use parallel processing architectures of interconnected microprocessors (which can execute many instructions at the same time in parallel). Can perform arithmetic calculations at speeds of billions of floating- come in operations per second (gigaflops). teraflop (1 trillion floating-point operations per second) supercomputers, which use advanced massively parallelprocessing (MPP) designs of thousands of interconnected microprocessors, are becoming available. Purchase price for large supercomputers are in the $5 million to $50 million range.Mini-supercomputersThe use of rhombohedral multiprocessing (SMP) and distributed shared retrospect (DSM) designs of smaller numbers of interconnected microprocessors has spawned a breed of mini-supercomputer with prices that start in the hundreds of thousands of dollars.TECHNICAL NOTE THE COMPUTER SYSTEM CONCEPTS Figure 13.9As a business professional, you do not need a detailed technical knowledge of computers. However , you do need to ascertain some basic facts and concepts about computer systems. This should help you be an informed and amentiferous user of computer system resources.A computer is a system, an co-ordinated combination of components that perform the basic system functions of input, processing, output, storage, and control, and so providing end users with a powerful information-processing tool. Understanding the computer as a computer system is vital to the effective use and management of computers. A computer is a system of hardware devices organised according to the following system functions Input. Examples of some input devices of a computer system include1. Keyboards2. Touch natural coverings3. depress Pens4. Electronic Mice4. opthalmic Scanners5. Voice InputThey convert data into electronic machine-readable form for enjoin entry or by a telecommunications network into a computer system.Processing. The central processing unit (CPU) is the main processing component of a computer system. (In microcomputers, it is the main microprocessor). matchless of the CPUs major components is the arithmetic-logic unit (ALU) that performs the arithmetic and logic functions required in computer processing. Components of the CPU include1. Control Unit 2. Arithmetic-Logic Unit 3. primary winding shop UnitOutput. Convert electronic information produced by the computer system into human-intelligible form for presentation to end-users.Examples of output devices include1. television set Display Units 2. sound Response Units 3. Printers computer storage. The storage function of a computer system is used to store data and program instructions postulate for processing. retentiveness devices include1. Primary stock Unit (main repositing)2. Secondary terminus gubbinss ( magnetised magnetized dish antenna and register units, ocular plows)Control. The control unit of a CPU interprets computer program instructions and transmits directions to the other compone nts of the computer system.Computer Processing SpeedsOperating speeds of computers are measured in a number of ways. For example Milliseconds Thousands of a second.Microseconds Millionths of a second.Nanoseconds Billionth of a secondPicosecond Trillionth of a secondOther terminology used includesTeraflop used by some supercomputersMIPS Million instructions per secondMegahertz (MHz) Millions of cycles per secondGigahertz (GHz) Billions of cycles per secondClock Speed used to rate microprocessors by the speed of their measure circuits and internal clock.Section II Computer Peripherals Input, Output, and Storage TechnologiesINTRODUCTIONA computer is just a high-powered processing box without peripherals. Your personal computing needs will dictate the components you choose for our cave inicular computing needs. Analyzing United Technologies and Eastman KodakWe can learn a lot about the business appreciate of consolidating computer operations and systems from this case. Take a few minutes to read it, and we will discuss it (See United Technologies and Eastman Kodak in Section IX).PERIPHERALSPeripherals are the generic name for all input, output, and secondary coil storage devices that are array of a computer system. Peripherals depend on direct connections or telecommunications cogitate to the central processing unit of acomputer system. Thus, all peripherals are online devices, that is, separate from, but can be electronically connected to and controlled by, a CPU. This is the opposite of off-line devices, which are separate from and not under the control of the CPU.INPUT TECHNOLOGYThere has been a major trend toward the increased use of input technologies that deliver a more indispensable user interface for computer users. more(prenominal) and more data and commands are cosmos entered directly and easily into computer systems by means of pointing devices like electronic mice and touch pads, and technologies like ocular examine, handwriting recognition, and voice recognition.POINTING DEVICESKeyboards are excuse the around widely used devices for entering data and text into computer systems. However, pointing devices are a better alternative for issuing commands, making choices, and responding to prompts screeninged on your video screen. They work with your operating systems graphical user interface (GUI), which presents you with icons, menus, windows, buttons, nix, and so on, for your selection. Examples of pointing devices include Electronic Mouse A device used to fall upon the cursor on the screen, as well as to young commands and make icon and menu selections. Trackball A device used to move the cursor on the display screen.Pointing stay on A small spangly device, sometimes likened to the eraser head of a pencil. The cursor moves in the direction of the insistence you place on the track point. Touchpad A small rectangular touch-sensitive go up usually placed below the keyboard. The cursor moves in th e direction your finger moves on the pad.Touch Screens A device that accepts data input by the placement of a finger on or close to the cathode-ray tube screen.PEN-BASED COMPUTINGPen-based computing technologies are world used in many hold computers and personal digital assistants. These small PCs and PDAs contain fast processors and software that recognises and digitises handwriting, hand printing, and hand drawing. They have a pressure-sensitive layer like a graphics pad under their slatelike liquid crystal display (LCD) screen.A variety of penlike devices are availableDigitizer Pen A photoelectronic device that can be used as a pointing device, or used to draw or write on a pressure-sensitive surface of a graphics tablet.Graphics Tablet A device that allows an end user to draw or write on a pressure-sensitive tablet and has their handwriting or graphics digitised by the computer and accepted as input. delivery RECOGNITION SYSTEMSSpeech recognition and voice response (in the ir infancy) promise to be the easiest method of data entry, word processing, and conversational computing, since dustup is the easiest, most natural means of human communication.Speech recognition systems analyse and classify address or vocal tract patterns and convert them into digital codes for entry into a computer system. Early voice recognition products used discrete actors line recognition, where you had to pause between distributively spoken word. New continuous speech recognition (CSR) software recognises controlled, conversationally paced speech. Examples of continuous speech recognition software include NaturallySpeaking by Dragon Systems ViaVoice by IBM VoiceXpress by Lernout & Hauspie FreeSpeech by PhilipsAreas where speech recognition systems are used include Manufacturers use it for inspection, inventory, and quality control Airlines and parcel delivery companies use it for voice-directed sorting of baggage and parcels Voice touch off GPS systems are being used in advanced car design Physicians use it to enter and printout prescriptions Gemmologists use it to free up their hands when inspecting and place precious stones Handicapped mortals use voice-enabled software to operate their computers, e-mail, and surf the solid ground Wide Web.Speaker-independent voice recognition systems allow a computer to understand a few words from a voice it has never comprehend before. They enable computers to respond to verbal and touch-tone input over the telephone.Examples include Computerized telephone call switching Telemarketing surveys Bank pay-by-phone bill-paying service Stock quotations services University registration systems Customer credit and account balance inquiriesOPTICAL examineOptical scanning devices read text or graphics and convert them into digital input for a computer. Optical scanning enables the direct entry of data from source documents into a computer system.Popular uses of optical scanning include Scanning varlets of text an d graphics into your computer for desktop publishing and web publishing applications. Scan documents into your system and organize them into folders as part of a document management library system for easy cite or retrieval.There are many types of optical scanners, but they all employ photoelectric devices to scan the characters being read. Reflected light patterns of thedata are converted into electronic impulses that are then accepted as input into the computer system.Optical scanning engine room known as optical character recognition (OCR) can read special-purpose characters and codes. OCR scanners are used to read characters and codes onMerchandise tagsProduct labelsCredit poster receipts inferior billsInsurance premiumsAirline ticketsSort mailScore testsProcess business and government formsDevices such as handheld optical scanning wands are used to read OCR coding on merchandise tags and other media. more business applications involve reading bar code, a code that utilise s bars to represent characters. One parking area example is the Universal Produce engrave (UPC) bar coding that you see on packages of food items and many other products.OTHER INPUT TECHNOLOGIES magnetised stripe technology is a familiar form of data entry that helps computers read credit cards. The dark charismatic stripe on the back of such cards is the same iron oxide coating as on magnetised immortalise. Smart cards that establish a microprocessor dapple and several(prenominal) kilobytes of memory into debit entry, credit, and other cards are popular in Europe, and becoming available in the United States. Digital cameras and digital video cameras enable you to shoot, store, and download still photos or full motion video with audio into your PC. magnetised ink character recognition (MICR) is machine recognition of characters printed with magnetised ink. Primarily used for check processing by the banking industry.OUTPUT TECHNOLOGIESComputers provide information in a vari ety of forms. Video displays and printed documents have been, and still are, the most common forms of output from computer systems. But other natural and attractive output technologies such as voice response systems and multimedia output are increasingly found along with video displays in business applications.VIDEO OUTPUTVideo displays are the most common type of computer output. Most desktop computers rely on video monitors that use cathode ray tube (CRT) technology. commonly, the pellucidity of the video display depends on the type of video monitor you use and the graphics circuit board installed in your computer. A high-resolution, flicker-free monitor is especially important if you spend a lot of time viewing multimedia on CDs or the Web, or complex graphical displays of many software packages.The biggest use of liquid crystal displays (LCDs) is to provide a opthalmic display capability for portable microcomputers and PDAs. LCD displays need significantly less electric curre nt and provide a thin, flat display.Advances in technology such as active matrix and dual scan capabilities have modify the color and clarity of LCD displays.PRINTED OUTPUTAfter video displays, printed output is the most common form of output displays. Most personal computer systems rely on inkjet or laser printers to produce permanent (hard copy) output in high-quality printed form. Printed output is still a common form of business communications, and is frequently required for legal documentation. Inkjet printers Spray ink onto a page one line at a time. They are popular, low-cost printers for microcomputer systems. They are quiet, produce several pages per minute of high-quality output, and can print both black-and-white and high-quality colour graphics.Laser Printers Use an electrostatic process analogous to a photocopying machine to produce many pages per minute of high-quality black-and-white output. to a greater extent expensive colour laser printers and multifunction in kjet and laser models that print, fax, scan, and copy are other popular choices for business offices. retentiveness TRADE-OFFSselective information and information need to be stored after input, during processing, and before output. Computer-based information systems rely primarily on the memory circuits and secondary storage devices of computer systems to accomplish the storage function.Major trends in primary and secondary storage methods Progress in very-large scale consolidation (VLSI), which packs millions of memory circuit elements on small semiconductor unit device memory chips, are responsible for continuing increases in the main-memory capacity of computers. Secondary storage capacities are also expected to escalate into the billions and trillions of characters, due primarily to the use of opticalmedia.Storage Trade-offs Speed, capacity, and cost relationships. Note the cost/speed/capacity trade-offs as one moves from semiconductor memories to magnetic media, such as mag netic discuss and tapes, to optical magnetic discs. High-speed storage media cost more per byte and provide lower capacities. giant capacity storage media cost less per byte but are lazy semiconductor unit memories are used principally for primary storage, though they are sometimes used as high-speed secondary storage devices. magnetized phonograph recording and tape and optical disk devices are used as secondary storage devices to greatly enlarge the storage capacity of computer systems. Most primary storage circuits use RAM (random access memory) chips, which lose their contents when electrical power is interrupted Secondary storage devices provide a more permanent type of storage media for storage of data and programs.Computer Storage Fundamentals Figure 13.20Data is processed and stored in a computer system through the strawman or absence of electronic or magnetic signals in the computers circuitry in the media it uses. This is called a two-state or binary star represen tation of data, since the computer and media can exhibit sole(prenominal) two possible states or conditions ON (1) or OFF (0).Computer storage elements Bit is the smallest element of data, (binary digit) which can have a value of zero or one. The capacity ofmemory chips is usually expressed in terms of bits.Byte is the basic grouping of bits that the computer operates as a whiz unit. It typically consists of 8 bits and is used to represent one character of data in most computer coding schemes (e.g. 8 bits = 1 byte). The capacityof a computers memory and secondary storage devices is usually expressed in terms of bytes. ASCII (American Standard Code for Information Interchange)EBCDIC (Extended binary star Coded Decimal Interchange Code) Pronounced EB SEE DICKStorage capacities are frequently measured inKilobyte= 1,000 bytesMegabyte= 1,000,000 bytesGigabyte= 1,000,000,000 bytes tebibyte= 1,000,000,000,000 bytesPetabyte= 1,000,000,000,000,000 bytesExabyte= 1,000,000,000,000,000,00 0 bytesZettabyte= 1,000,000,000,000,000,000,000 bytesYottabyte= 1,000,000,000,000,000,000,000,000 bytesDirect and Sequential Access Direct Access Primary storage media such as semiconductor memory chips are called direct access or random access memories (RAM). Magnetic disk devices are frequently called direct access storage devices (DASDs).The terms direct access and random access describe the same concept. They mean that an element of data or instructions can be directly stored and retrieved by selecting and using any of the locations on the storage media. They also mean that each storage position (1) has a unique address and (2) can be singly accessed in approximately the same length of time without having to search through other storage positions.Sequential Access successive access storage media such as magnetic tape do not have unique storage addresses that can be directly addressed. Instead, data moldiness be stored and retrieved using a sequential or serial process. Data are recorded one after another in a predetermined sequence on a storage moderate. Locating an individual item of data requires searching much of the recorded data on the tape until the desired item is located.SEMICONDUCTOR MEMORYThe primary storage (main memory) on most modern computers consists of microelectronic semiconductor memory circuits. Plug-in memory circuit boards containing 32 megabytes or more of memory chips can be added to your PC to increase its memory capacity. Specialized memory can help improve your computers performance. Examples include foreign cache memory of 512 kilobytes to help your microprocessor work faster Video graphics accelerator cards with 16 megabytes of RAM are used for faster and clearer video performance removable credit-card-size and smaller flash memory RAM cards provide several megabytes of erasable direct access storage for PDAs or hand-held PCs.Some of the major attractions of semiconductor memory are Small size Fast speed Shock and tempera ture resistanceOne major impairment of most semiconductor memory is Volatility Uninterrupted electric power must be supplied or the contents of memory will be lost (except withread exclusively memory, which is permanent).There are two basic types of semiconductor memory Random Access remembering (RAM) these memory chips are the most widely used primary storage medium. Each memory position can be both read and written, so it is also called read/write memory. This is a volatile memory.Read Only Memory ( read-only storage) Non-volatile random access memory chips are used for permanent storage. read-only memory can be read but not erased or overwritten. instructions and programs in primary storage can be permanently burned into the storage cells during manufacturing. This permanent software is also called firmware. Variations include mall (programmable read only memory) and EPROM (erasable programmable read only memory), which can be permanently or temporarily programmed after manufacture.MAGNETIC DISK STORAGEThese are the most common forms of secondary storage for modern computer systems. Thats because they provide fast access and high storage capacities at a reasonable cost. Characteristics of magnetic disks magnetic disc vexs contain metal disks that are coated on both sides with an iron oxide recording material. Several disks are mounted together on a vertical shaft, which typically rotates the disks are speeds of 3,600 to 7,600 revolutions per minute (rpm) Access arms between the slightly separated disks to read and write data on concentric, circular tracks position electromagnetic read/write heads. Data are recorded on tracks in the form of piffling magnetized drifter to form the binary digits of common computer codes. Thousands of bytes can be recorded on each track, and there are several hundred data tracks on each disk surface, which provides you with billions of storage positions for software and data. Types of Magnetic magnetic disksThere are several types of magnetic disk arrangements, including disk cartridges as well as fixed disk units. Removable disk devices are popular because they are transportable and can be used to store backup copies of your data off-line for convenience and security. diskette dish aerials, or magnetic disks, consist of polyester film disks covered with an iron oxide compound. A single disk is mounted and rotates freely inside a tutelary flexible or hard plastic jacket, which has access openings to accommodate the read/write head of a disk drive unit. The 3-1/2-inch floppy disk, with capacities of 1.44 megabytes, is the most widely used version, with a newer Superdisk technology offering 120 megabytes of storage. Hard Disk Drives combine magnetic disks, access arms, and read/write heads into a sealed module. This allows higher speeds, greater data-recording densities,and closer tolerances within a sealed, more stable environment. Fixed or removable disk cartridge versions are available. Ca pacities of hard drives range from several hundred megabytes to many gigabytes of storage.RAID StorageDisk arrays of interconnected microcomputer hard disk drives have replaced large-capacity mainframe disk drives to provide many gigabytes of online storage. Known as RAID (redundant arrays of independent disks), they combine from 6 to more than 100 small hard disk drives and their control microprocessors into a single unit. Advantages of RAID disks include Provide large capacities with high access speeds since data is accessed in parallel over eighter from Decatur-fold paths from many disks. Provide fault tolerant capability, since their redundant design offers aggregate copies of data on several disks. If one disk fails, data can be recovered from backup copies automatically stored on other disks. Storage area networks (SANs) are high-speed fibre channel local area networks that can interconnect many RAID units and share their combined capacity through network servers for many u sers.MAGNETIC TAPE STORAGEMagnetic Tape is still being used as a secondary storage medium in business applications. The read/write heads of magnetic tape drives record data in the form of magnetised floater on the iron oxide coating of the plastic tape. Magnetic tape devices include tape reels and cartridges in mainframes and midrange systems, and small cassettes or cartridges for PCs.These devices serve as poky, but lower cost, storage to supplement magnetic disks to meet massive data warehouse and other business storage requirements. Other major applications for magnetic tape include long-term archival storage and backup storage for PCs and other systems.OPTICAL DISK STORAGEOptical disk storage involves technology, which is based on using a laser toread tiny spots on a plastic disk. The disks are currently sure-footed of storing billions of characters of information. load down disc read-only memory A common type of optical disk used on microcomputers. They are used for read on ly storage. Storage is over 600 megabytes per disk. This is homogeneous to over 400 1.44-megabyte floppy disks or 300,000 double-spaced pages of text. Data are recorded as microscopic pits in a curlicue track, and are read using a laser device.Limitation save data cannot be erasedCD-R ( covenant disk recordable) is another optical disk technology. It enables computers with CD-R disk drive units to record their own data once on a CD, and then be able to read the data indefinitely. Limitation Recorded data cannot be erasedCD-RW (CD-rewritable) optical disk systems have now become available which record and erase data by using a laser to heat a microscopic point on the disks surface. In CD-RW versions using magneto-optical technology, a magnetic coil changes the spots reflective properties from one direction to another, thus recording a binary one to zero. A laser device can then read the binary codes on the disk by sensing the direction of reflected light. videodisk (Digital Vid eo Disk or Digital Versatile Disk) can hold from 3.0 to 8.5 gigabytes of multimedia data on each side of a bundle disk. The large capacities and high- quality images and sound of videodisk technology are expected to eventually replace CD-ROM and CD-RW technologies for data storage, andpromise to accelerate the use of DVD drives for multimedia products that can be used in both computers and home entertainment systems. DVD-ROM is beginning to replace magnetic tape videocassettes for movies and other multimedia products. DVD RAM is being used for backup and archival storage data and multimedia files. traffic ApplicationsOne of the major uses of optical disks in mainframe and midrange systems is in image processing, where longterm archival storage of historical files of document images must be maintained. Mainframe and midrange computer versions of optical disks use 12-inch plastic disks with capacities of several gigabytes, with up to 20 disks held in jukebox drive units. WORM (Wri te Once, Read Many) versions of optical disks are used to store data on the disk. Although data can only be stored once, it can be read an infinite number of times.One of the major business uses of CD-ROM disks for personal computers is to provide a publishing medium for fast access to reference materials in a convenient, compact form. These include Catalogs Directories ManualsPeriodical abstractsPart listingsStatistical databases of business activity and stinting activity Interactive multimedia applications in business, education, and entertainment usingCD-ROM and DVD disks.Optical disks have become a popular storage medium for image processing and multimedia business applications and they appear to be a promising alternative to magnetic disks and tape for very large mass storage capabilities for enterprise computing systems. However, rewritable optical technologies are still being perfected. Also, most optical disk devices are significantly slower and more expensive (per byte of s torage) than magnetic disk devices. So optical disk systems are not expected to displace magnetic disk technology in the near future for most business applications.IV. KEY name AND CONCEPTS DEFINEDBinary RepresentationPertaining to the presence or absence of electronic or magnetic signals in the computers circuitry or in the media it uses. There are only two possible states or conditions presence or absence. Central Processing Unit (CPU)The unit of a computer system that includes the circuits that controls the interpretation and execution of instructions. In many computer systems, the CPU includes the arithmetic-logic unit, the control unit, and primary storage unit.Computer SystemComputer hardware as a system of input, processing, output, storage, and control components. Thus a computer system consists of input and output devices, primary and secondary storage devices, the central processing unit, the control unit within the CPU, and other peripheral devices.Computer TerminalAny input/output device connected by telecommunications links to a computer.Digital CamerasDigital still cameras and digital video cameras enable you to shoot, store, and download still photos or full-motion video with audio in your PC.Direct AccessA method of storage where each storage position has a unique address and can be severally accessed in approximately the same period of time without having to search through other storage positions. Information ApplianceDevices for consumers to access the Internet.Laptop ComputerA small portable PC.Liquid Crystal Displays (LCD)Electronic visual displays that form characters by applying an electrical charge to selected silicon crystals.Magnetic Disk StorageData storage technology that uses magnetised spots on metal or plastic disks. Magnetic Disk Storage floppy disk DiskSmall phonograph record enclosed in a protective envelope. It is a widely used form of magnetic disk media that provides a direct access storage capability for microcomputer systems. Magnetic Disk Storage Hard DiskSecondary storage medium generally nonremovable disks made out of metal and covered with a magneticrecording surface. It holds data in the form of magnetised spots.Magnetic Disk Storage RAIDRedundant array of independent disks. Magnetic disk units that house many interconnected microcomputer hard disk drives, thus providing large, fault tolerant storage capacities. Magnetic Ink Character erudition (MICR)The machine recognition of characters printed with magnetic ink. Primarily used for check processing by the banking industry.Magnetic StripeA magnetic stripe card is a plastic wallet-size card with a strip of magnetic tape on one surface widely used for credit/debit cards.Magnetic TapeA plastic tape with a magnetic surface on which data can be stored by selective magnetisation of portions of the surface.Mainframe ComputerA larger-size computer system, typically with a separate central processing unit, as distinguished from microcomputer and minicomputer systems.MicrocomputerA very small computer, ranging in size from a Computer on a chip to a small typewriter-size unit. MicroprocessorA semiconductor chip with circuitry for processing data.Midrange ComputerLarger and more powerful than most microcomputers but are smaller and less powerful than most large mainframe computer systems.MinicomputerA small electronic general-purpose computer.Network ComputerA new category of microcomputer designed mainly for use with the Internet and Intranets on tasks requiring limited or specialised applications and no or minimal disk storage. Network ServerA type of midrange computer used to co-ordinate telecommunications and resource sharing and manages large web sites, Intranets, extranets, and client/server networks.Network TerminalA terminal that depends on network servers for its software and processing power. Off-linePertaining to equipment or devices not under control of the central processing unit. OnlinePertaining to equipment or devices under control of the central processing unit. Optical Character Recognition (OCR)The machine identification of printed characters through the use of light-sensitive devices. Optical Disk StorageTechnology based on using a laser to read tiny spots on a plastic disk. The disks are currently capable of storing billions of characters of information.Optical Disk Storage CD-ROMAn optical disk technology for microcomputers featuring compact disks with a storage capacity of over 500 megabytes.Optical Disk Storage CD-RCompact disk recordable (CD-R) enables computers with CD-R disk drive units to record their own data once on a CD, than be able to read the data indefinitely.Optical Disk Storage CD-RWCompact disk rewritable (CD-RW) enables computers with CD-RW disk drive units to record and erase data by using a laser to heat a microscopic point on the disks surface. Optical Disk Storage DVDDigital video disk or digital versatile disk (DVD) enables computers with DVD disk drive uni ts to hold from 3.0 to 8.5 gigabytes of multimedia data on each side of a compact disk. Optical Disk Storage WORM DiskOptical disk that allows users to write once, read many times.Optical ScanningUsing a device (scanner) that scans characters or images and generates their digital representations. Pen-Based ComputingTablet-style microcomputers that recognise hand-writing and hand-drawing done by a pen-shaped device on their pressure sensitive display screens.Peripheral DevicesIn a computer system, any unit of equipment, distinct from the central processing unit, that provides the system with input, output, or storage capabilities.Personal Digital AssistantHandheld microcomputer devices, which are designed for convenient mobile communications and computing. Pointing DevicesDevices, which allow end users to young commands or make choices by moving a cursor on the display, screen. Pointing Device Electronic MouseA small device that is electronically connected to a computer and is mov ed by hand on a flat surface in order to move the cursor on a video screen in the same direction. Buttons on the mouse allow users to issue commands and makeresponses or selections.Pointing Device Pointing StickA small buttonlike device sometimes likened to the eraser head of a pencil. The cursor moves in the direction of the pressure you place on the track point.Pointing Device TouchpadIs a small rectangular touch-sensitive surface usually placed below the keyboard. The cursor moves in the direction your finger moves on the pad.Pointing Device TrackballA roller device set in a case used to move the cursor on a computers display screen. Primary StorageThe main (or internal) memory of a computer. Usually in the form of semiconductor storage. PrintersDevices that produce hard copy output such as paper documents or reports. Secondary StorageExternal or auxiliary storage device that supplements the primary storage of a computer.Semiconductor MemoryMicroelectronic storage circuitry et ched on tiny chips of silicon or other semiconducting material.Semiconductor Memory RAMAlso known as main memory or primary storage type of memory that temporarily holds data and instructions needed shortly by the CPU. RAM is a volatile type of storage. Semiconductor Memory ROMAlso known as firmware a memory chip that permanently stores instructions and data that are programmed during the chips manufacture. Three variations on the ROM chip are PROM, EPROM, and EEPROM. ROM is a nonvolatile form of storage. Sequential AccessA sequential method of storing and retrieving data from a file.Smart CardsCards such as debit and credit cards, which have an embedded microprocessorchip and several kilobytes of memory.Speech RecognitionDirect conversion of spoken data into electronic form suitable for entry into a computer system. Promises to be the easiest, most natural way to communicate with computers.Storage might ElementsUnits used for storage capacity and data bits, bytes, kilobytes (KB) , megabytes (MB), gigabytes (GB), terabytes (TB).Storage force Elements BitA compaction of binary digit. It can have the value of either 0 or1. Storage Capacity Elements ByteA sequence of adjacent binary digits operated on as a unit and usually shorter than a computer word. In many computer systems, a byte is a grouping of eight bits that can represent one alphabetic or special character or can be packed with two decimal digits.Storage Capacity Elements Kilobyte (K or KB)When referring to computer storage capacity it is equivalent to 2 to the 10th power, or 1,014 in decimal notation.Storage Capacity Elements Megabyte (MB)One million bytes. More accurately, 2 to the 20th power, 1,048,576 in decimal notation.Storage Capacity Elements Gigabyte (GB)One billion bytes. More accurately, 2 to the 30th power, or 1,073,741,824 in decimal notation.Storage Capacity Elements Terabyte (TB)One trillion bytes. More accurately, 2 to the 40th power, or 1,009,511,627,776 in decimal notation.St orage Media Trade-offsThe trade-offs in cost, speed, and capacity of various storage media.SupercomputerA special category of large computer systems that are the most powerful available. They are designed to solve massive computational problems. time ElementsUnits used for measuring processing speeds milliseconds, microseconds, nanoseconds, and picoseconds.Time Elements MillisecondA 1000th of a second.Time Elements MicrosecondA millionth of a second.Time Elements NanosecondOne billionth of a second.Time Elements PicosecondOne trillionth of a second.Touch-Sensitive ScreenAn input device that accepts data input by the placement of a finger on or close to the CRT screen.Transaction TerminalsTerminals used in banks, retail stores, factories, and other work sites that are used to overtake transaction data at their point of origin. Examples are point-of-sale (POS) terminals and automated teller machines (ATMs).Video OutputVideo displays are the most common type of computer output.V olatilityMemory (such as electronic semiconductor memory) that loses its contents when electrical power is interrupted. WandA handheld optical character recognition device used for data entry by many transaction terminals. WorkstationA computer terminal or micro- or minicomputer system designed to support the work of one person. Also, a highpowered computer to support the work of professionals in engineering, science, and other areas that require extensive computing power and graphics capabilities.V. DISCUSSION QUESTIONSDo you agree with the statement The network is the computer?What trends are occurring in the development and use of the major types of computer systems?Do you think that network computers (NCs) will replace personal computers (PCs) in business applications?Are networks of PCs and servers making mainframe computers obsolete?Whattrends are occurring in the development and use of peripheral devices? Why are those trends occurring?When would you recommend the use of each of the followingNetwork computersNetPCsNetwork terminalsInformation appliances in business applicationsWhat processor, memory, magnetic disk storage, and video display capabilities would you require for a personal computer that you would use for business purposes?What other peripheral devices and capabilities would you want to have for your business PC?