I. LECTURE OVERVIEW
Foundation Concepts: Computer Hardware. reexamine tendencies and developments in personal computer. midrange. and mainframe computing machine systems ; basic computing machine system constructs ; and the major types of engineerings used in peripheral devices for computing machine input. end product. and storage.
Computer Systems – Major types of computing machine systems are summarized in Figure 13. 2. A computing machine is a system of information processing constituents that perform input. processing. end product. storage. and control maps. Its hardware constituents include input and end product devices. a cardinal processing unit ( CPU ) . and primary and secondary storage devices. The major maps and hardware in a computing machine system are summarized in Figure 13. 9
Microcomputer Systems – Microcomputers are used as personal computing machines. web computing machines. personal digital helpers. proficient workstations. and information contraptions. Like most computing machine systems today. personal computers are interconnected in a assortment of telecommunications webs. This typically includes local country webs. client/server webs. intranets and extranets. and the Internet. Other Computer Systems – Midrange computing machines are progressively used as powerful web waiters. and for many multiuser concern informations processing and scientific applications. Mainframe computing machines are larger and more powerful than most midsize computing machines. They are normally faster. hold more memory capacity. and can back up more web users and peripheral devices. They are designed to manage the information processing demands of big organisations with high volumes of dealing processing. or with complex computational jobs. Supercomputers are a particular class of highly powerful mainframe computing machine systems designed for monolithic computational assignments.
II. LEARNING OBJECTIVES
Learning Objective
• Identify the major types. tendencies. and utilizations of personal computer. midrange and mainframe computing machine systems.
• Outline the major engineerings and utilizations of computing machine peripherals for input. end product. and storage.
• Identify and give illustrations of the constituents and maps of a computing machine system.
• Identify the computing machine systems and peripherals you would get or urge for a concern of your pick. and explicate the grounds for your choices.
III. LECTURE Notes
Section 1: Computer Systems: End User and Enterprise Computing
Introduction
All computing machines are systems of input. processing. end product. storage. and control constituents. Technology is germinating at a rapid gait. and new signifiers of input. end product. processing. and storage devices continue to come in the market. Analyzing City of Richmond and Tim Beaty Builders
We can larn a batch about advanced concern utilizations of PDAs from this instance. Take a few proceedingss to read it. and we will discourse it ( See City of Richmond and Tim Beaty Builders in Section IX ) .
TYPES OF COMPUTER SYSTEMS – [ Figure 13. 2 ]
There are several major classs of computing machine systems with a assortment of features and capablenesss. Therefore. computing machine systems are typically classified as:
• Mainframe computing machines
• Midrange computing machines
• Personal computers
These classs are efforts to depict the comparative calculating power provided by different calculating platforms or types of computing machines hence. they are non precise categorizations. Some experts predict the meeting or disappearing of several computing machine classs. They feel that many midrange and mainframe systems have been made disused by the power and versatility of client/server webs of personal computers and waiters. Most late. some industry experts have predicted that the outgrowth of web computing machines and information contraptions for applications on the Internet and corporate intranets will replace many personal computing machines. particularly in big administrations and in the place computing machine market.
MICROCOMPUTER SYSTEMS
Personal computers are the smallest but most of import classs of computing machines systems for concern people and consumers. They are besides referred to as personal computing machines ( or Personal computers ) . The calculating power of current personal computers exceeds that of the mainframe computing machines of old coevalss at a fraction of their cost. They have become powerful-networked professional workstations for usage by terminal users in concern.
Personal computers categorised by size
1. Handheld
2. Notebook
3. Laptop
4. Portable
5. Desktop
6. Floor-standing
Personal computers categorised by usage
1. Home
2. Personal
3. Professional
4. Workstation
5. Multi-user Systems
Personal computers categorised by particular intent
1. Workstation Computers
2. Network Waiters
3. Personal Digital Assistants
Workstation Computers – some personal computers are powerful workstation computing machines ( proficient work Stationss ) that support applications with heavy mathematical computer science and artworks display demands such as computeraided design ( CAD ) in technology. or investing and portfolio analysis in the securities industry. Network Servers – are normally more powerful personal computers that co-ordinate telecommunications and resource sharing in little local country webs ( LANs ) . and Internet and intranet web sites. This is the fastest turning microcomputer application class.
Network Computers:
• Network Computers ( NCs ) are a major new personal computer class designed chiefly for usage with the Internet and corporate intranets by clerical workers. operational employees. and knowledge workers with specialized or limited computer science applications.
In-between NCs and full-featured Personal computers are stripped-down Personal computers known as NetPCs or legacy-free Personal computers. NetPCs are designed for the Internet and a limited scope of applications within a company. Examples are: Dell’s Webpc. Compaq’s IPaq. HP’s e-PC. and eMachine’s eOne.
Network computing machines ( besides called thin clients ) are low-priced. sealed. networked personal computers with no or minimum disc storage. Users of web computing machines depend chiefly on Internet and intranet waiters for their operating system and net browser. Java-enabled application package. and informations entree and storage. Main attractive forces of web computing machines over full-featured Personal computers are their low cost to:
• Purchase
• Ascent
• Care
• Support
Other benefits to concerns include:
• Ease of package distribution and licensing
• Calculating platform standardization
• Reduced terminal user support demands
• Improved manageableness through centralised direction and enterprisewide control of computing machine web resources.
Information Appliances
The market is offering a figure of appliances and information contraptions that offer users the capableness to execute enable host of basic computational jobs. Examples of some information contraptions include: • Personal Digital Assistants – ( PDAs ) are designed for convenient Mobile communications and calculating. PDAs usage touch screens. pen-based script acknowledgment. or keyboards to assist nomadic workers send and receive E-mail. entree the Web. and exchange information such as assignments. to-do lists. and gross revenues contacts with their desktop Personal computers or web waiters.
• Set-top boxes and video-game consoles that connect to home Television sets. These devices enable you to surf the Web or direct and have E-mail and watch Television plans or play video games at the same clip.
• Wireless PDAs and cellular and PCS phones and wired telephone-based contraptions that can direct and have E-mail and entree the Web.
Computer Terminals
Computer terminuss are undergoing a major transition to networked computing machine devices. For illustration: • Dumb terminuss are keyboard/video proctor devices with limited processing capablenesss. to intelligent terminuss. which are modified networked Personal computers. web computing machines or other microcomputer-powered web devices. Intelligent terminuss can execute informations entry and some information processing undertakings independently. • Networked terminuss which may be Windows terminuss that are dependent on web waiters for Windows package. treating power. and storage. or Internet terminuss. which depend on Internet or intranet website waiters for their operating systems and application package. • Transaction terminuss are a signifier of intelligent terminus. Uses can be found in Bankss retail shops. mills. and other work sites. Examples are ATM’s. mill production recording equipments. and POS terminuss.
MIDRANGE COMPUTER SYSTEMS
Midrange computing machines. including minicomputers and high-end web waiters. are multi-user systems that can pull off webs of Personal computers and terminuss. Features of midrange computing machines include:
• Generally. midrange computing machines are all-purpose computing machines that are larger and more powerful than most personal computers but are smaller and less powerful than most big mainframes.
• Cost less to purchase. operate. and maintain than mainframe computing machines.
• Have become popular as powerful web waiters to assist pull off big Internet web sites. corporate intranets and extranets. and client/server webs.
• Electronic commercialism and other concern utilizations of the Internet are popular high-end waiter applications. as are incorporate enterprisewide fabrication. distribution. and fiscal applications.
• Data warehouse direction. information excavation. and on-line analytical processing are lending to the growing of high-end waiters and other midrange systems.
• First became popular as minicomputers for scientific research. instrumentality systems. technology analysis. and industrial procedure monitoring and control. Minicomputers could easy manage such utilizations because these applications are narrow in range and make non demand the processing versatility of mainframe systems.
• Serve as industrial process-control and fabrication works computing machines and they play a major function in computeraided fabrication ( CAM ) .
• Take the signifier of powerful proficient workstations for computer-aided design ( CAD ) and other calculation and graphics-intensive applications.
• Are used as front-end computing machines to help mainframe computing machines in telecommunications processing and web direction.
• Can work in ordinary operating environments ( do non necessitate air conditioning or electrical wiring ) . • Smaller theoretical accounts of minicomputers do non necessitate a staff of specializers to run them.
MIDRANGE COMPUTER APPLICATIONS
Serve as industrial process-control and fabrication works computing machines. Play a major function in computer-aided fabrication ( CAM ) .
Serve as powerful proficient workstations for computer-aided design ( CAD ) and other calculation and graphics-intensive applications
Serve as front-end computing machines to help mainframe computing machines in telecommunications processing and web direction.
Midrange Computer as Network Server:
• Electronic commercialism and other concern utilizations of the Internet are popular high-end waiter applications. as are incorporate enterprisewide fabrication. distribution. and fiscal applications.
• Other applications. like informations warehouse direction. information excavation. and on-line analytical processing are lending to the growing of high-end waiters and other midrange systems.
• Serve as powerful web waiters to assist pull off big Internet web sites. corporate Intranets and extranets. and client/server webs
MAINFRAME COMPUTER SYSTEMS
Mainframe computing machines are big. fast. and powerful computing machine systems. Features of mainframe computing machines include:
• They are physically larger and more powerful than micros and minis.
• Can treat 100s of 1000000s of instructions per second ( MIPS ) .
• Have big primary storage capacities. Main memory capacity can run from 100s of Ms to many Gs of primary storage.
• Mainframes have slimmed down drastically in the last few old ages. dramatically cut downing air-conditioning demands. electronic power ingestion. and floor infinite demands. and therefore their acquisition and operating costs.
• Gross saless of mainframes have increased due to be decreases and the addition in applications such as informations excavation and repositing. determination support. and electronic commercialism.
Mainframe Computer Applications:
• Handle the information processing demands of major corporations and authorities bureaus with many employees and clients.
• Handle tremendous and complex computational jobs.
• Used in administrations treating great volumes of minutess.
• Handle great volumes of complex computations involved in scientific and technology analyses and simulations of complex design undertakings.
• Serve as superservers for the big client/server webs and high-volume Internet web sites of big companies.
• Are going a popular business-computing platform for informations excavation and repositing. and electronic commercialism applications.
Supercomputer Systems:
The term supercomputer describes a class of highly powerful computing machine systems specifically designed for scientific. technology. and concern applications necessitating highly high-speeds for monolithic numeral calculations.
Supercomputer Applications:
• Used by authorities research bureaus. big universities. and major corporations.
• Are used for applications such as planetary conditions prediction. military defense mechanism systems. computational cosmology and uranology. microprocessor research and design. big graduated table informations excavation. big time-sharing webs. and so on.
• Use analogue processing architectures of interrelated microprocessors ( which can put to death many instructions at the same clip in analogue ) .
• Can execute arithmetic computations at velocities of one million millions of floating-point operations per second ( gigaflops ) . Teraflop ( 1 trillion floating-point operations per second ) supercomputers. which use advanced massively parallel processing ( MPP ) designs of 1000s of interrelated microprocessors. are going available. • Purchase monetary value for big supercomputers are in the $ 5 million to $ 50 million scope.
Mini-supercomputers:
The usage of symmetric parallel processing ( SMP ) and distributed shared memory ( DSM ) designs of smaller Numberss of interrelated microprocessors has spawned a strain of mini-supercomputer with monetary values that start in the 100s of 1000s of dollars.
Technical Note: THE COMPUTER SYSTEM CONCEPTS – [ Figure 13. 9 ]
As a concern professional. you do non necessitate a elaborate proficient cognition of computing machines. However. you do necessitate to understand some basic facts and constructs about computing machine systems. This should assist you be an informed and productive user of computing machine system resources.
A computing machine is a system. an interconnected combination of constituents that perform the basic system maps of input. processing. end product. storage. and control. therefore supplying terminal users with a powerful information-processing tool. Understanding the computing machine as a computing machine system is critical to the effectual usage and direction of computing machines. A computing machine is a system of hardware devices organised harmonizing to the undermentioned system maps:
• Input. Examples of some input devices of a computing machine system include:
1. Keyboards
2. Touch Screens3. Light Pens
4. Electronic Mouse
4. Optical Scanners
5. Voice Input
They convert informations into electronic machine-readable signifier for direct entry or through a telecommunications web into a computing machine system.
Processing. The cardinal processing unit ( CPU ) is the chief processing constituent of a computing machine system. ( In personal computers. it is the chief microprocessor ) . One of the CPU’s major constituents is the arithmetic-logic unit ( ALU ) that performs the arithmetic and logic maps required in computing machine processing. Components of the CPU include:
1. Control Unit 2. Arithmetic-Logic Unit 3. Primary Storage Unit of measurement
Output. Convert electronic information produced by the computing machine system into human-intelligible signifier for presentation to end-users.
Examples of end product devices include:
1. Video Display Units 2. Audio Response Units 3. Printers
Storage. The storage map of a computing machine system is used to hive away informations and plan instructions needed for processing.
Storage devices include:
1. Primary Storage Unit ( chief memory )
2. Secondary Storage Devicess ( magnetic disc and tape units. optical discs )
Control. The control unit of a CPU interprets computing machine plan instructions and transmits waies to the other constituents of the computing machine system.
Computer Processing Speeds:
Operating velocities of computing machines are measured in a figure of ways. For illustration: • Milliseconds – Thousands of a 2nd.
Microseconds – Millionths of a 2nd.
Nanoseconds – Billionth of a 2nd
Picosecond – Trillionth of a 2nd
Other nomenclature used includes:
Teraflop – used by some supercomputers
MIPS – Million instructions per second
Megahertz ( MHz ) – Millions of rhythms per second
Gigahertz ( GHz ) – Billions of rhythms per second
Clock Speed – used to rate microprocessors by the velocity of their timing circuits and internal clock.
Section II: Computer Peripherals: Input. Output. and Storage Technologies
Introduction
A computing machine is merely a high-octane “processing box” without peripherals. Your personal computer science demands will order the constituents you choose for our peculiar computer science demands. Analyzing United Technologies and Eastman Kodak
We can larn a batch about the concern value of consolidating computing machine operations and systems from this instance. Take a few proceedingss to read it. and we will discourse it ( See United Technologies and Eastman Kodak in Section IX ) .
Peripherals
Peripherals are the generic name for all input. end product. and secondary storage devices that are portion of a computing machine system. Peripherals depend on direct connexions or telecommunications links to the cardinal processing unit of a computing machine system. Therefore. all peripherals are on-line devices. that is. separate from. but can be electronically connected to and controlled by. a CPU. This is the antonym of off-line devices. which are separate from and non under the control of the CPU.
INPUT TECHNOLOGY
There has been a major tendency toward the increased usage of input engineerings that provide a more natural user interface for computing machine users. More and more informations and bids are being entered straight and easy into computing machine systems through indicating devices like electronic mice and touch tablets. and engineerings like optical scanning. handwriting acknowledgment. and voice acknowledgment.
POINTING Devicess
Keyboards are still the most widely used devices for come ining informations and text into computing machine systems. However. indicating devices are a better option for publishing bids. doing picks. and reacting to motivate displayed on your picture screen. They work with your runing system’s graphical user interface ( GUI ) . which presents you with icons. bill of fare. Windowss. buttons. bars. and so on. for your choice. Examples of indicating devices include:
• Electronic Mouse – A device used to travel the pointer on the screen. every bit good as to publish bids and do icon and bill of fare choices.
• Trackball – A device used to travel the pointer on the show screen.
Indicating Stick – A little buttonlike device. sometimes likened to the eraser caput of a pencil. The pointer moves in the way of the force per unit area you place on the path point. Touchpad – A little rectangular touch-sensitive surface normally placed below the keyboard. The pointer moves in the way your finger moves on the tablet.
Touch Screens – A device that accepts informations input by the arrangement of a finger on or shut to the CRT screen.
PEN-BASED Computer science
Pen-based computer science engineerings are being used in many handheld computing machines and personal digital helpers. These little Personal computers and PDAs contain fast processors and package that recognises and digitises handwriting. manus printing. and manus pulling. They have a pressure-sensitive bed like a artworks tablet under their slatelike liquid crystal show ( LCD ) screen.
A assortment of penlike devices are available:
Digitizer Pen – A photoelectronic device that can be used as a pointing device. or used to pull or compose on a pressure-sensitive surface of a artworks tablet.
Artworks Tablet – A device that allows an terminal user to pull or compose on a pressure-sensitive tablet and has their script or artworks digitised by the computing machine and accepted as input.
SPEECH RECOGNITION SYSTEMS
Speech acknowledgment and voice response ( in their babyhood ) promise to be the easiest method of informations entry. word processing. and colloquial computer science. since address is the easiest. most natural agencies of human communicating.
Speech acknowledgment systems analyse and sort address or vocal piece of land forms and change over them into digital codifications for entry into a computing machine system. Early voice acknowledgment merchandises used distinct address acknowledgment. where you had to hesitate between each spoken word. New uninterrupted address acknowledgment ( CSR ) package recognises controlled. colloquially paced address. Examples of uninterrupted address acknowledgment package include: • NaturallySpeaking by Dragon Systems
• ViaVoice by IBM
• VoiceXpress by Lernout & A ; Hauspie
• FreeSpeech by Philips
Areas where address acknowledgment systems are used include:
• Manufacturers use it for review. stock list. and quality control
• Airlines and parcel bringing companies use it for voice-directed sorting of luggage and packages
• Voice activated GPS systems are being used in advanced auto design
• Physicians use it to come in and printout prescriptions
• Gemmologists use it to liberate up their custodies when inspecting and rating cherished rocks
• Handicapped persons use voice-enabled package to run their computing machines. electronic mail. and surf the World Wide Web.
Speaker-independent voice acknowledgment systems allow a computing machine to understand a few words from a voice it has ne’er heard before. They enable computing machines to react to verbal and touch-tone input over the telephone.
Examples include:
• Computerized telephone call shift
• Telemarketing studies
• Bank pay-by-phone bill-paying services
• Stock citations services
• University enrollment systems
• Customer recognition and history balance enquiries
OPTICAL Scanning
Optical scanning devices read text or artworks and change over them into digital input for a computing machine. Optical scanning enables the direct entry of informations from beginning paperss into a computing machine system.
Popular utilizations of optical scanning include:
• Scaning pages of text and artworks into your computing machine for desktop publication and web publication applications.
• Scan paperss into your system and form them into booklets as portion of a papers direction library system for easy mention or retrieval. There are many types of optical scanners. but they all employ photoelectric devices to scan the characters being read. Reflected light forms of the informations are converted into electronic urges that are so accepted as input into the computing machine system.
Optical scanning engineering known as optical character acknowledgment ( OCR ) can read special-purpose characters and codifications. OCR scanners are used to read characters and codifications on:
Merchandise ticket
Merchandise labels
Credit card grosss
Utility measures
Insurance premiums
Airline tickets
Sort mail
Mark trials
Procedure concern and authorities signifiers
Devicess such as hand-held optical scanning wands are used to read OCR coding on ware ticket and other media. Many concern applications involve reading saloon codification. a codification that utilises bars to stand for characters. One common illustration is the Universal Produce Code ( UPC ) saloon coding that you see on bundles of nutrient points and many other merchandises.
OTHER INPUT TECHNOLOGIES
Magnetic band engineering is a familiar signifier of informations entry that helps computing machines read recognition cards. The dark magnetic band on the dorsum of such cards is the same Fe oxide surfacing as on magnetic tape. Smart cards that embed a microprocessor bit and several Ks of memory into debit. recognition. and other cards are popular in Europe. and going available in the United States. Digital cameras and digital picture cameras enable you to hit. shop. and download still photos or full gesture picture with audio into your Personal computer.
Magnetic ink character acknowledgment ( MICR ) is machine acknowledgment of characters printed with magnetic ink. Primarily used for cheque processing by the banking industry.
OUTPUT TECHNOLOGIES
Computers provide information in a assortment of signifiers. Video shows and printed paperss have been. and still are. the most common signifiers of end product from computing machine systems. But other natural and attractive end product engineerings such as voice response systems and multimedia end product are progressively found along with picture shows in concern applications.
VIDEO OUTPUT
Video shows are the most common type of computing machine end product. Most desktop computing machines rely on picture proctors that use cathode beam tubing ( CRT ) engineering. Normally. the lucidity of the picture show depends on the type of picture proctor you use and the artworks circuit board installed in your computing machine. A high-resolution. flicker-free proctor is particularly of import if you spend a batch of clip sing multimedia on Cadmiums or the Web. or complex graphical shows of many package bundles.
The biggest usage of liquid crystal shows ( LCDs ) is to supply a ocular show capableness for portable personal computers and PDAs. LCD shows need significantly less electric current and supply a thin. level show.
Progresss in engineering such as active matrix and double scan capablenesss have improved the colour and lucidity of LCD shows.
PRINTED OUTPUT
After picture shows. printed end product is the most common signifier of end product shows. Most personal computing machine systems rely on inkjet or optical maser pressmans to bring forth lasting ( difficult transcript ) end product in high-quality printed signifier. Printed end product is still a common signifier of concern communications. and is often required for legal certification. • Inkjet pressmans – Spray ink onto a page one line at a clip. They are popular. low-priced pressmans for personal computer systems. They are quiet. bring forth several pages per minute of high-quality end product. and can publish both black-and-white and high-quality coloring material artworks.
Laser Printers – Use an electrostatic procedure similar to a photocopying machine to bring forth many pages per minute of high-quality black-and-white end product. More expensive coloring material optical maser pressmans and multifunction inkjet and optical maser theoretical accounts that print. facsimile. scan. and transcript are other popular picks for concern offices.
Storage Tradeoff
Data and information demand to be stored after input. during processing. and before end product. Computer-based information systems rely chiefly on the memory circuits and secondary storage devices of computing machine systems to carry through the storage map.
Major tendencies in primary and secondary storage methods:
• Progress in very-large graduated table integrating ( VLSI ) . which packs 1000000s of memory circuit elements on bantam semiconducting material memory french friess. are responsible for go oning additions in the main-memory capacity of computing machines.
• Secondary storage capacities are besides expected to intensify into the one million millions and millions of characters. due chiefly to the usage of optical
media. Storage Tradeoffs: Speed. capacity. and cost relationships.
• Note the cost/speed/capacity trade-offs as one moves from semiconducting material memories to magnetic media. such as magnetic discs and tapes. to optical discs.
• High-speed storage media cost more per byte and supply lower capacities.
• Large capacity storage media cost less per byte but are slower
• Semiconductor memories are used chiefly for primary storage. though they are sometimes used as high-velocity secondary storage devices.
• Magnetic disc and tape and optical disc devices are used as secondary storage devices to greatly enlarge the storage capacity of computing machine systems.
• Most primary storage circuits use RAM ( random entree memory ) french friess. which lose their contents when electrical power is interrupted
• Secondary storage devices provide a more lasting type of storage media for storage of informations and plans.
Computer Storage Fundamentalss: [ Figure 13. 20 ]
Data is processed and stored in a computing machine system through the presence or absence of electronic or magnetic signals in the computer’s circuitry in the media it uses. This is called a “two-state” or binary representation of informations. since the computing machine and media can exhibit merely two possible provinces or conditions – ON ( 1 ) or OFF ( 0 ) .
Computer storage elements:
• Bit – is the smallest component of informations. ( binary figure ) which can hold a value of zero or one. The capacity of memory french friess is normally expressed in footings of spots.
Byte – is the basic grouping of spots that the computing machine operates as a individual unit. It typically consists of 8 spots and is used to stand for one character of informations in most computing machine coding strategies ( e. g. 8 spots = 1 byte ) . The capacity
of a computer’s memory and secondary storage devices is normally expressed in footings of bytes. ASCII ( American Standard Code for Information Interchange )
EBCDIC ( Extended Binary Coded Decimal Interchange Code ) Pronounced: EB SEE DICK
Storage capacities are often measured in:
Kilobyte
= 1. 000 bytes
Megabyte
= 1. 000. 000 bytes
Gigabyte
= 1. 000. 000. 000 bytes
Terabyte
= 1. 000. 000. 000. 000 bytes
Petabyte
= 1. 000. 000. 000. 000. 000 bytes
Exabyte
= 1. 000. 000. 000. 000. 000. 000 bytes
Zettabyte
= 1. 000. 000. 000. 000. 000. 000. 000 bytes
Yottabyte
= 1. 000. 000. 000. 000. 000. 000. 000. 000 bytes
Direct and Consecutive Access
• Direct Access – Primary storage media such as semiconducting material memory french friess are called direct entree or random entree memories ( RAM ) . Magnetic disc devices are often called direct entree storage devices ( DASDs ) .
The footings direct entree and random entree describe the same construct. They mean that an component of informations or instructions can be straight stored and retrieved by choosing and utilizing any of the locations on the storage media. They besides mean that each storage place ( 1 ) has a alone reference and ( 2 ) can be separately accessed in about the same length of clip without holding to seek through other storage places.
Consecutive Access – consecutive entree storage media such as magnetic tape do non hold alone storage references that can be straight addressed. Alternatively. informations must be stored and retrieved utilizing a consecutive or consecutive procedure. Datas are recorded one after another in a preset sequence on a storage medium. Locating an single point of informations requires seeking much of the recorded information on the tape until the coveted point is located.
SEMICONDUCTOR MEMORY
The primary storage ( chief memory ) on most modern computing machines consists of microelectronic semiconducting material memory circuits. Plug-in memory circuit boards incorporating 32 Ms or more of memory french friess can be added to your Personal computer to increase its memory capacity. Specialized memory can assist better your computer’s public presentation. Examples include:
• External cache memory of 512 Ks to assist your microprocessor work faster
• Video artworks gas pedal cards with 16 Ms of RAM are used for faster and clearer picture public presentation
• Removable credit-card-size and smaller “flash memory” RAM cards provide several Ms of effaceable direct entree storage for PDAs or handheld Personal computers.
Some of the major attractive forces of semiconducting material memory are:
• Small size
• Fast velocity
• Shock and temperature opposition
One major disadvantage of most semiconductor memory is:
• Volatility – Uninterrupted electric power must be supplied or the contents of memory will be lost ( except with read merely memory. which is lasting ) .
There are two basic types of semiconducting material memory:
• Random Access Memory ( RAM ) – these memory french friess are the most widely used primary storage medium. Each memory place can be both read and written. so it is besides called read/write memory. This is a volatile memory.
• Read Merely Memory ( ROM ) – Non-volatile random entree memory french friess are used for lasting storage. ROM can be read but non erased or overwritten. Instruction manuals and plans in primary storage can be for good “burned in” to the storage cells during fabrication. This lasting package is besides called microcode. Variations include PROM ( programmable read merely memory ) and EPROM ( effaceable programmable read merely memory ) . which can be for good or temporarily programmed after industry.
MAGNETIC DISK STORAGE
These are the most common signifiers of secondary storage for modern computing machine systems. That’s because they provide fast entree and high storage capacities at a sensible cost. Features of magnetic discs:
• Disk thrusts contain metal discs that are coated on both sides with an Fe oxide entering stuff.
• Several discs are mounted together on a perpendicular shaft. which typically rotates the discs are velocities of 3. 600 to 7. 600 revolutions per minute ( revolutions per minute )
• Access weaponries between the somewhat detached discs to read and compose informations on concentric. round paths place electromagnetic read/write caputs.
• Datas are recorded on paths in the signifier of bantam magnetic musca volitanss to organize the binary figures of common computing machine codifications.
• Thousands of bytes can be recorded on each path. and there are several hundred informations paths on each disc surface. which provides you with one million millions of storage places for package and informations. Types of Magnetic Disks
There are several types of magnetic disc agreements. including disc cartridges every bit good as fixed disc units. Removable disc devices are popular because they are movable and can be used to hive away backup transcripts of your informations off-line for convenience and security.
Floppy Disks. or magnetic discs. consist of polyester movie discs covered with an Fe oxide compound. A individual disc is mounted and rotates freely inside a protective flexible or difficult plastic jacket. which has entree gaps to suit the read/write caput of a disk thrust unit. The 3-1/2-inch floppy disc. with capacities of 1. 44 Ms. is the most widely used version. with a newer Superdisk engineering offering 120 Ms of storage. Hard Disk Drives combine magnetic discs. entree weaponries. and read/write caputs into a certain faculty. This allows higher velocities. greater data-recording densenesss. and closer tolerances within a certain. more stable environment. Fixed or removable disc cartridge versions are available. Capacities of difficult thrusts range from several hundred Ms to many Gs of storage.
RAID Storage
Disk arrays of interrelated personal computer difficult disc thrusts have replaced large-capacity mainframe disc thrusts to supply many Gs of on-line storage. Known as RAID ( excess arrays of independent discs ) . they combine from 6 to more than 100 little difficult disc thrusts and their control microprocessors into a individual unit. Advantages of RAID discs include:
• Provide big capacities with high entree velocities since information is accessed in analogue over multiple waies from many discs.
• Provide mistake tolerant capableness. since their redundant design offers multiple transcripts of informations on several discs. If one disc fails. informations can be recovered from backup transcripts automatically stored on other discs. • Storage country webs ( SANs ) are high-velocity fibre channel local country webs that can complect many RAID units and portion their combined capacity through web waiters for many users.
MAGNETIC TAPE STORAGE
Magnetic Tape is still being used as a secondary storage medium in concern applications. The read/write caputs of magnetic tape drives record informations in the signifier of magnetic musca volitanss on the Fe oxide coating of the plastic tape. Magnetic tape devices include tape reels and cartridges in mainframes and midrange systems. and little cassettes or cartridges for Personal computers.
These devices serve as slower. but lower cost. storage to supplement magnetic discs to run into monolithic informations warehouse and other concern storage demands. Other major applications for magnetic tape include long-run archival storage and backup storage for Personal computers and other systems.
OPTICAL DISK STORAGE
Optical disc storage involves engineering. which is based on utilizing a optical maser to
read bantam musca volitanss on a fictile disc. The discs are presently capable of hive awaying one million millions of characters of information.
• CD-ROM – A common type of optical disc used on personal computers. They are used for read merely storage. Storage is over 600 Ms per disc. This is tantamount to over 400 1. 44-megabyte floppy discs or 300. 000 double-spaced pages of text. Datas are recorded as microscopic cavities in a coiling path. and are read utilizing a optical maser device.
Restriction: Recorded informations can non be erased
• CD-R – ( Compact disk recordable ) is another optical disc engineering. It enables computing machines with CD-R disc thrust units to enter their ain informations one time on a Cadmium. and so be able to read the informations indefinitely. Restriction: Recorded informations can non be erased
• CD-RW – ( CD-rewritable ) optical disc systems have now become available which record and wipe out informations by utilizing a optical maser to heat a microscopic point on the disk’s surface. In CD-RW versions utilizing magneto-optical engineering. a magnetic spiral changes the spot’s brooding belongingss from one way to another. therefore entering a binary one to zero. A optical maser device can so read the binary codifications on the disc by feeling the way of reflected visible radiation.
• DVD – ( Digital Video Disk or Digital Versatile Disk ) can keep from 3. 0 to 8. 5 Gs of multimedia informations on each side of a compact disc. The big capacities and high- quality images and sound of DVD engineering are expected to finally replace CD-ROM and CD-RW engineerings for informations storage. and assure to speed up the usage of DVD thrusts for multimedia merchandises that can be used in both computing machines and place amusement systems.
• DVD-ROM is get downing to replace magnetic tape videocassettes for films and other multimedia merchandises.
• DVD – RAM is being used for backup and archival storage informations and multimedia files.
Business Applications
One of the major utilizations of optical discs in mainframe and midrange systems is in image processing. where longterm archival storage of historical files of papers images must be maintained. Mainframe and midrange computing machine versions of optical discs use 12-inch plastic discs with capacities of several Gs. with up to 20 discs held in jukebox drive units. WORM – ( Write Once. Read Many ) versions of optical discs are used to hive away informations on the disc. Although informations can merely be stored one time. it can be read an infinite figure of times.
One of the major concern utilizations of CD-ROM discs for personal computing machines is to supply a publication medium for fast entree to cite stuffs in a convenient. compact signifier. These include:
• Catalogs
• Directories
• Manuals
• Periodical abstracts
• Part listings
• Statistical databases of concern activity and economic activity Interactive multimedia applications in concern. instruction. and amusement utilizing
CD-ROM and DVD discs.
Optical discs have become a popular storage medium for image processing and multimedia concern applications and they appear to be a promising option to magnetic discs and tape for really big mass storage capablenesss for endeavor calculating systems. However. rewritable optical engineerings are still being perfected. Besides. most optical disc devices are significantly slower and more expensive ( per byte of storage ) than magnetic disc devices. So optical disc systems are non expected to displace magnetic disc engineering in the close hereafter for most concern applications.
IV. KEY TERMS AND CONCEPTS – DEFINED
Binary Representation:
Refering to the presence or absence of electronic or magnetic “signals” in the computer’s circuitry or in the media it uses. There are merely two possible provinces or conditions – presence or absence. Cardinal Processing Unit ( CPU ) :
The unit of a computing machine system that includes the circuits that controls the reading and executing of instructions. In many computing machine systems. the CPU includes the arithmetic-logic unit. the control unit. and primary storage unit.
Computer System:
Computer hardware as a system of input. processing. end product. storage. and control constituents. Therefore a computing machine system consists of input and end product devices. primary and secondary storage devices. the cardinal processing unit. the control unit within the CPU. and other peripheral devices.
Computer Terminal:
Any input/output device connected by telecommunications links to a computing machine.
Digital Cameras:
Digital still cameras and digital picture cameras enable you to hit. shop. and download still photos or full-motion picture with audio in your Personal computer.
Direct Entree:
A method of storage where each storage place has a alone reference and can be separately accessed in about the same period of clip without holding to seek through other storage places. Information Appliance:
Devicess for consumers to entree the Internet.
Laptop Computer:
A little portable Personal computer.
Liquid Crystal Displays ( LCD ) :
Electronic ocular shows that form characters by using an electrical charge to selected Si crystals.
Magnetic Disk Storage:
Data storage engineering that uses magnetic musca volitanss on metal or plastic discs. Magnetic Disk Storage – Floppy Disk:
Small record player record enclosed in a protective envelope. It is a widely used signifier of magnetic disc media that provides a direct entree storage capableness for personal computer systems. Magnetic Disk Storage – Hard Disk
Secondary storage medium ; by and large nonremovable discs made out of metal and covered with a magnetic recording surface. It holds informations in the signifier of magnetic musca volitanss.
Magnetic Disk Storage – RAID
Excess array of independent discs. Magnetic disc units that house many interconnected microcomputer difficult disc thrusts. therefore supplying big. mistake tolerant storage capacities. Magnetic Ink Character Recognition ( MICR ) :
The machine acknowledgment of characters printed with magnetic ink. Primarily used for cheque processing by the banking industry.
Magnetic Band:
A magnetic band card is a fictile wallet-size card with a strip of magnetic tape on one surface ; widely used for credit/debit cards.
Magnetic Tape:
A fictile tape with a magnetic surface on which informations can be stored by selective magnetization of parts of the surface.
Mainframe Computer:
A larger-size computing machine system. typically with a separate cardinal processing unit. as distinguished from personal computer and minicomputer systems.
Personal computer:
A really little computing machine. runing in size from a “Computer on a chip” to a little typewriter-size unit. Microprocessor:
A semiconducting material bit with circuitry for treating informations.
Midrange Computer:
Larger and more powerful than most personal computers but are smaller and less powerful than most big mainframe computing machine systems.
Minicomputer:
A little electronic all-purpose computing machine.
Network Computer:
A new class of personal computer designed chiefly for usage with the Internet and Intranets on undertakings necessitating limited or specialised applications and no or minimum disc storage. Network Waiter:
A type of midrange computing machine used to co-ordinate telecommunications and resource sharing and manages big web sites. Intranets. extranets. and client/server webs.
Network Terminal:
A terminus that depends on web waiters for its package and treating power. Off-line:
Refering to equipment or devices non under control of the cardinal processing unit. Online:
Refering to equipment or devices under control of the cardinal processing unit. Optical Character Recognition ( OCR ) :
The machine designation of printed characters through the usage of photosensitive devices. Optical Disk Storage:
Technology based on utilizing a optical maser to read bantam musca volitanss on a fictile disc. The discs are presently capable of hive awaying one million millions of characters of information.
Optical Disk Storage – CD-ROM:
An optical disc engineering for personal computers having compact discs with a storage capacity of over 500 Ms.
Optical Disk Storage – CD-R:
Compact disc recordable ( CD-R ) enables computing machines with CD-R disc thrust units to enter their ain informations one time on a Cadmium. than be able to read the informations indefinitely.
Optical Disk Storage – CD-RW:
Compact disc rewritable ( CD-RW ) enables computing machines with CD-RW disc thrust units to record and wipe out informations by utilizing a optical maser to heat a microscopic point on the disk’s surface. Optical Disk Storage – DVD:
Digital picture disc or digital various disc ( DVD ) enables computing machines with DVD disc thrust units to keep from 3. 0 to 8. 5 Gs of multimedia informations on each side of a compact disc. Optical Disk Storage – WORM Disk:
Optical disc that allows users to compose one time. read many times.
Optical Scanning:
Using a device ( scanner ) that scans characters or images and generates their digital representations. Pen-Based Computer science:
Tablet-style personal computers that recognise hand-writing and hand-drawing done by a pen-shaped device on their force per unit area sensitive show screens.
Peripheral Devicess:
In a computing machine system. any unit of equipment. distinct from the cardinal processing unit. that provides the system with input. end product. or storage capablenesss.
Personal Digital Assistant:
Handheld personal computer devices. which are designed for convenient Mobile communications and calculating. Indicating Devicess:
Devicess. which allow terminal users to publish bids or do picks by traveling a pointer on the show. screen. Indicating Device – Electronic Mouse:
A little device that is electronically connected to a computing machine and is moved by manus on a level surface in order to travel the pointer on a picture screen in the same way. Buttons on the mouse allow users to publish bids and do responses or choices.
Indicating Device – Pointing Stick:
A little buttonlike device sometimes likened to the eraser caput of a pencil. The pointer moves in the way of the force per unit area you place on the path point.
Indicating Device – Touchpad:
Is a little rectangular touch-sensitive surface normally placed below the keyboard. The pointer moves in the way your finger moves on the tablet.
Indicating Device – Trackball:
A roller device set in a instance used to travel the pointer on a computer’s show screen. Primary Storage:
The chief ( or internal ) memory of a computing machine. Normally in the signifier of semiconducting material storage. Printers:
Devicess that produce difficult transcript end product such as paper paperss or studies. Secondary Storage:
External or subsidiary storage device that supplements the primary storage of a computing machine.
Semiconductor Memory:
Microelectronic storage circuitry etched on bantam french friess of Si or other semiconducting stuff.
Semiconductor Memory – RAM:
Besides known as chief memory or primary storage ; type of memory that temporarily holds informations and instructions needed shortly by the CPU. RAM is a volatile type of storage. Semiconductor Memory – ROM:
Besides known as microcode ; a memory bit that for good shops instructions and informations that are programmed during the chip’s industry. Three fluctuations on the ROM bit are PROM. EPROM. and EEPROM. ROM is a nonvolatilizable signifier of storage. Consecutive Entree:
A consecutive method of hive awaying and recovering informations from a file.
Smart Card games:
Card games such as debit and recognition cards. which have an embedded microprocessor
bit and several Ks of memory.
Speech Recognition:
Direct transition of spoken informations into electronic signifier suitable for entry into a computing machine system. Promises to be the easiest. most natural manner to pass on with computing machines.
Storage Capacity Elementss:
Unit of measurements used for storage capacity and informations: spots. bytes. Ks ( KB ) . Ms ( MB ) . Gs ( GB ) . TBs ( TB ) .
Storage Capacity Elements – Bit:
A contraction of “binary digit” . It can hold the value of either 0 or
1. Storage Capacity Elements – Byte:
A sequence of next binary figures operated on as a unit and normally shorter than a computing machine word. In many computing machine systems. a byte is a grouping of eight spots that can stand for one alphabetic or particular character or can be “packed” with two denary figures.
Storage Capacity Elements – Kilobyte ( K or KB ) :
When mentioning to computing machine storage capacity it is tantamount to 2 to the tenth power. or 1. 014 in denary notation.
Storage Capacity Elements – Megabyte ( MB ) :
One million bytes. More accurately. 2 to the twentieth power. 1. 048. 576 in denary notation.
Storage Capacity Elements – Gigabyte ( GB ) :
One billion bytes. More accurately. 2 to the thirtieth power. or 1. 073. 741. 824 in denary notation.
Storage Capacity Elements – Terabyte ( TB ) :
One trillion bytes. More accurately. 2 to the fortieth power. or 1. 009. 511. 627. 776 in denary notation.
Storage Media Tradeoffs:
The tradeoffs in cost. velocity. and capacity of assorted storage media.
Supercomputer:
A particular class of big computing machine systems that are the most powerful available. They are designed to work out monolithic computational jobs.
Time Elementss:
Unit of measurements used for mensurating processing velocities: msecs. microseconds. nanoseconds. and picoseconds.
Time Elements – Millisecond:
A thousandth of a 2nd.
Time Elements – Microsecond:
A millionth of a 2nd.
Time Elements – Nanosecond:
One billionth of a 2nd.
Time Elements – Picosecond:
One trillionth of a 2nd.
Touch-Sensitive Screen:
An input device that accepts informations input by the arrangement of a finger on or shut to the CRT screen.
Transaction Terminals:
Terminals used in Bankss. retail shops. mills. and other work sites that are used to capture dealing informations at their point of beginning. Examples are point-of-sale ( POS ) terminuss and machine-controlled Teller machines ( ATMs ) .
Video Output:
Video shows are the most common type of computing machine end product.
Volatility:
Memory ( such as electronic semiconducting material memory ) that loses its contents when electrical power is interrupted. Wand:
A hand-held optical character acknowledgment device used for informations entry by many dealing terminuss. Workstation:
A computing machine terminus or micro- or minicomputer system designed to back up the work of one individual. Besides. a highpowered computing machine to back up the work of professionals in technology. scientific discipline. and other countries that require extended calculating power and artworks capablenesss.
V. DISCUSSION QUESTIONS
Make you hold with the statement: “The web is the computer” ?
What trends are happening in the development and usage of the major types of computing machine systems?
Do you believe that web computing machines ( NCs ) will replace personal computing machines ( Personal computers ) in concern applications?
Are webs of Personal computers and waiters doing mainframe computing machines obsolete?
What trends are happening in the development and usage of peripheral devices? Why are those tendencies happening?
When would you urge the usage of each of the followers:
Network computing machines
NetPCs
Network terminuss
Information contraptions in concern applications
What processor. memory. magnetic disc storage. and video show capablenesss would you necessitate for a personal computing machine that you would utilize for concern intents?
What other peripheral devices and capablenesss would you desire to hold for your concern Personal computer?
