What is a Process?What is a Process? A process is a computer program running

on a computer. A computer program in simple terms is an

executable set of commands for the computer to perform. A process is an actively running program which may or may not be running in the background. A program running in the background is one that the computer user may not be aware of, but it may be providing useful services such as an ability to connect to other computers.

THE CENTRAL PROCESSING THE CENTRAL PROCESSING UNIT UNIT

This is the This is the “brain” of the computer“brain” of the computer; it reads ; it reads and executes program instructions, performs and executes program instructions, performs calculations, and makes decisions .calculations, and makes decisions .

The CPU is responsible for storing and The CPU is responsible for storing and retrieving information on disks and other retrieving information on disks and other media. It also handles information on from media. It also handles information on from one part of the computer to another like a one part of the computer to another like a central switching station that directs the central switching station that directs the flow of traffic throughout the computer flow of traffic throughout the computer system.system.

DIFFERENT FACES OF A CPUDIFFERENT FACES OF A CPU

MAIN COMPONENTS OF CPUMAIN COMPONENTS OF CPU

WHAT DOES THE CPU DO?WHAT DOES THE CPU DO?

Carries out instructionsCarries out instructions and tells the and tells the rest of computer system what to do. rest of computer system what to do.

Sends command signalsSends command signals to the other to the other components of the system. components of the system.

PerformPerform arithmetic calculations and arithmetic calculations and data manipulation. data manipulation.

HoldsHolds data and instructions, which data and instructions, which are in current use.are in current use.

CONTROL UNIT (CU) CONTROL UNIT (CU) Directs the entire computer system Directs the entire computer system

to carry out stored program to carry out stored program instructions.instructions.

Instructs the arithmetic logic unit Instructs the arithmetic logic unit which arithmetic operations or logical which arithmetic operations or logical operation is to be performed. operation is to be performed.

ARITHMETIC LOGIC UNIT ARITHMETIC LOGIC UNIT (ALU) (ALU)

ExecutesExecutes arithmetic and logical arithmetic and logical operations. operations.

Arithmetic operations include Arithmetic operations include addition, subtraction, multiplication addition, subtraction, multiplication and division. and division.

Logical operations compare numbers, Logical operations compare numbers, letters and special characters. letters and special characters.

MEMORY UNITMEMORY UNIT Holds data and instructions for Holds data and instructions for

processing. processing.

a)a) RAM (Random Access Memory)RAM (Random Access Memory) - used to - used to store instructions and data needed while store instructions and data needed while processing.processing.

b) b) ROM (Read Only Memory)ROM (Read Only Memory) - ROM comes - ROM comes with instructions permanently stored with instructions permanently stored inside and these instructions cannot be inside and these instructions cannot be over-written by the computer’s CPU.over-written by the computer’s CPU.

MICROPROCESSORMICROPROCESSOR A A silicon chipsilicon chip that contains a that contains a

CPU. In the world of personal CPU. In the world of personal computers, the terms computers, the terms microprocessormicroprocessor and CPU and CPU are are used interchangeablyused interchangeably..

It's sometimes called a It's sometimes called a logic logic chipchip. It is the "engine" that . It is the "engine" that goes into motion when you goes into motion when you turn your computer on.turn your computer on.

At the heart of all personal At the heart of all personal computers and most computers and most workstations sits a workstations sits a microprocessor. microprocessor. Microprocessors also Microprocessors also control control the logicthe logic of almost all digital of almost all digital devices, from clock radios to devices, from clock radios to fuel-injection systems for fuel-injection systems for automobiles. automobiles.

Three basic characteristics Three basic characteristics differentiate microprocessors: differentiate microprocessors:

Instruction setInstruction set: The set of : The set of instructions that the microprocessor instructions that the microprocessor can execute. can execute.

bandwidthbandwidth :: The number of bits The number of bits processed in a single instruction. processed in a single instruction.

clock speedclock speed :: Given in megahertz Given in megahertz (MHz), the clock speed determines (MHz), the clock speed determines how many instructions per second how many instructions per second the processor can execute. the processor can execute.

MICROPROCESSOR (cont.)MICROPROCESSOR (cont.) In both cases, the higher the value, the In both cases, the higher the value, the

more powerful the CPU. more powerful the CPU. For example, a 32-bit microprocessor that For example, a 32-bit microprocessor that

runs at 50MHz is more powerful than a 16-runs at 50MHz is more powerful than a 16-bit microprocessor that runs at 25MHz. bit microprocessor that runs at 25MHz.

In addition to bandwidth and clock speed, In addition to bandwidth and clock speed, microprocessors are classified as being microprocessors are classified as being either either RISC (reduced instruction set RISC (reduced instruction set computer) or CISC (complex instructioncomputer) or CISC (complex instruction set set computer). computer).

  

WHAT IS INPUT?WHAT IS INPUT?

Input is any data or instructions you enter into the memory of a computer. 

Once input is in memory, the CPU can access it and process the input into output.  Four types of input are data, programs, commands, and user responses.

4 TYPES OF INPUT4 TYPES OF INPUTData is a collection of unorganized

facts that can include words, numbers, pictures, sounds, and videos. 

A program is a series of instructions

that tells a computer how to perform the tasks necessary to process data into information.  Programs are kept on storage media such as a floppy disk, hard disk, CD-ROM, or DVD-ROM.

4 TYPES OF INPUT (cont.)4 TYPES OF INPUT (cont.)     A A commandcommand is an instruction given to is an instruction given to

a computer program.  Typing keywords a computer program.  Typing keywords or pressing special keys on the or pressing special keys on the keyboard can issue commands. keyboard can issue commands. 

A A user responseuser response is an instruction is an instruction you issue to the computer by you issue to the computer by replying to a question posed by a replying to a question posed by a computer program, such as do you computer program, such as do you want to save the change you made? want to save the change you made?

INPUT DEVICESINPUT DEVICES

An An input deviceinput device is any hardware is any hardware component that allows you to enter component that allows you to enter data, programs, commands, and user data, programs, commands, and user responses into a computer.  responses into a computer. 

Input devices include the Input devices include the keyboardkeyboard, , pointing devices, scannerspointing devices, scanners and and reading devices, digital cameras, reading devices, digital cameras, audioaudio and and video input devicesvideo input devices for for physically challenged user. physically challenged user. 

PEN INPUTPEN INPUT Many input devices use Many input devices use

an electronic pen an electronic pen instead of keyboard or instead of keyboard or mouse for input. Some mouse for input. Some of there devices require of there devices require you to point to you to point to onscreen objects with onscreen objects with the pen ;others allow the pen ;others allow you to input data using you to input data using drawings, handwriting, drawings, handwriting, and other symbols that and other symbols that are written with the are written with the pen on a surface.pen on a surface.

LIGHT PEN LIGHT PEN A A light penlight pen is a handheld input device that is a handheld input device that

contains a light source or can detect light. contains a light source or can detect light. Some light pens require a specially designed Some light pens require a specially designed

monitor, while others work with a standard monitor, while others work with a standard monitor. monitor.

LIGHT PENLIGHT PEN

Instead of touching the screen with your finger to Instead of touching the screen with your finger to interact with the computer, you press the light interact with the computer, you press the light pen against the surface of the screen or point the pen against the surface of the screen or point the light pen at the screen and then press a button light pen at the screen and then press a button on the pen. on the pen.

PEN COMPUTING PEN COMPUTING Many handheld computers also allow Many handheld computers also allow

inputting data using an electronic pen inputting data using an electronic pen (also called a (also called a stylusstylus) looks like a ) looks like a ballpoint pen but uses an electronic ballpoint pen but uses an electronic head instead of ink. head instead of ink.

Pen computers use handwriting Pen computers use handwriting recognition software that translates the recognition software that translates the letters and symbols used in handwriting letters and symbols used in handwriting into character data that the computers into character data that the computers can use. can use.

GRAPHICS TABLET GRAPHICS TABLET A A graphics tabletgraphics tablet, ,

also called a also called a digitizer digitizer or digitizing tablesor digitizing tables, , consists of a flat, consists of a flat, rectangular, rectangular, electronic plastic electronic plastic bond used to input bond used to input drawings, sketches, drawings, sketches, or other graphical or other graphical data. data.

Each location on the graphical tablet Each location on the graphical tablet corresponds to a specific location on the corresponds to a specific location on the screen. When you draw on the tablet with screen. When you draw on the tablet with either an electronic pen or a puck, the tablet either an electronic pen or a puck, the tablet detects and converts the movements into detects and converts the movements into digital signals that are sent into the digital signals that are sent into the computer. computer.

TRACKBALLTRACKBALL

A mechanical mouse has ball mechanism on the bottom, A mechanical mouse has ball mechanism on the bottom, a a trackballtrackball is a station- aryl pointing device with a ball is a station- aryl pointing device with a ball mechanism on its top . mechanism on its top .

Although it shares characteristic with a mouse, a Although it shares characteristic with a mouse, a trackball is trackball is not as accuratenot as accurate as a mouse .A trackballs ball as a mouse .A trackballs ball mechanism also requires frequent cleaning because it mechanism also requires frequent cleaning because it picks up oils from your fingers and dust from the picks up oils from your fingers and dust from the environment. environment.

CAMERACAMERA Digital cameraDigital camera allows you to allows you to

take pictures and store the take pictures and store the photographed images digitally photographed images digitally instead of on traditional film. instead of on traditional film.

With some digital cameras, With some digital cameras, you you downdownlloadoad, or transfer a , or transfer a copy of, the stored pictures to copy of, the stored pictures to your computer by connecting your computer by connecting a cable between the digital a cable between the digital camera and your computer camera and your computer and using special software and using special software included with the camera. included with the camera.

The The three basic types of three basic types of digital camerasdigital cameras are are studio studio cameras, field cameras, and cameras, field cameras, and point-and shoot- cameras.point-and shoot- cameras.

MOUSE MOUSE The The mousemouse is the most widely used is the most widely used

pointing device because it takes full pointing device because it takes full advantage of a graphical user advantage of a graphical user interface. interface.

A A mousemouse is an input device that is is an input device that is used to control the movement of the used to control the movement of the pointer on the screen and to make pointer on the screen and to make selections from the screen. selections from the screen.

MOUSE TYPES MOUSE TYPES A mouse that has a rubber or metal ball A mouse that has a rubber or metal ball

on its underside is called a on its underside is called a mechanical mechanical mousemouse. When the ball rolls in a certain . When the ball rolls in a certain direction, electronic circuits in the mouse direction, electronic circuits in the mouse translate the movement of the mouse translate the movement of the mouse into signals that are sent to the computer. into signals that are sent to the computer.

Another type of mouse, called Another type of mouse, called an an optical mouseoptical mouse, has no moving , has no moving mechanical parts inside; instead mechanical parts inside; instead it uses devices that emit light to it uses devices that emit light to detect the mouse’s movement. detect the mouse’s movement.

MOUSE OPERATIONS MOUSE OPERATIONS

SCANNERS SCANNERS Scanners have become an important part of the Scanners have become an important part of the

home office over the last few years. Scanner home office over the last few years. Scanner technology is everywhere and used in many ways: technology is everywhere and used in many ways:

Flatbed scannersFlatbed scanners, also called , also called desktop scanners, are the most desktop scanners, are the most versatile and commonly used versatile and commonly used scanners. In fact, this article will scanners. In fact, this article will focus on the technology as it focus on the technology as it relates to flatbed scanners.relates to flatbed scanners.

SCANNERS (cont.)SCANNERS (cont.) Sheet-fed scannersSheet-fed scanners

are similar to flatbed are similar to flatbed scanners except the scanners except the document is moved document is moved and the scan head is and the scan head is immobile. A sheet-immobile. A sheet-fed scanner looks a fed scanner looks a lot like a small lot like a small portable printer.portable printer.

SCANNERS (cont.)SCANNERS (cont.) Handheld scannersHandheld scanners

use the same basic use the same basic technology as a technology as a flatbed scanner, but flatbed scanner, but rely on the user to rely on the user to move them instead move them instead of a motorized belt. of a motorized belt. This type of scanner This type of scanner typically does not typically does not provide good image provide good image quality. However, it quality. However, it can be useful for can be useful for quickly capturing quickly capturing text. text.

SCANNERS (cont.)SCANNERS (cont.)

Drum scannersDrum scanners are used by the publishing are used by the publishing industry to capture incredibly detailed images. They industry to capture incredibly detailed images. They use a technology called a use a technology called a photo multiplier tubephoto multiplier tube (PMT). In PMT, the document to be scanned is (PMT). In PMT, the document to be scanned is mounted on a glass cylinder. At the center of the mounted on a glass cylinder. At the center of the cylinder is a sensor that splits light bounced from cylinder is a sensor that splits light bounced from the document into three beams. Each beam is sent the document into three beams. Each beam is sent through a color filter into a photo multiplier tube through a color filter into a photo multiplier tube where the light is changed into an electrical signal.where the light is changed into an electrical signal.

KEYBOARD TYPESKEYBOARD TYPES

A standard computer keyboard sometimes is called a A standard computer keyboard sometimes is called a QWERTY keyboardQWERTY keyboard because of the layout of its typing because of the layout of its typing area. area.

Pronounced KWER-tee, this keyboard layout is named Pronounced KWER-tee, this keyboard layout is named after the first six leftmost letters on the top alphabetic after the first six leftmost letters on the top alphabetic line of the keyboard. Because of the way the keys are line of the keyboard. Because of the way the keys are organized, a QWERTY keyboard might limit your typing organized, a QWERTY keyboard might limit your typing speed. speed.

KEYBOARD TYPES (cont.)KEYBOARD TYPES (cont.) A keyboard with an alternative layout was A keyboard with an alternative layout was

designed to improve typing speed called the designed to improve typing speed called the Dvorak keyboardDvorak keyboard (pronounced de-vor-zhak), (pronounced de-vor-zhak),

This type of keyboard places the most This type of keyboard places the most frequently typed letters in the middle of the frequently typed letters in the middle of the typing area. typing area.

Despite the more logical design of the Despite the more logical design of the Dvorak keyboard, the QWERTY keyboard is Dvorak keyboard, the QWERTY keyboard is more widely used. more widely used.

MICROPHONEMICROPHONE A A microphonemicrophone is used is used

to record sound.  The to record sound.  The sound is then saved as sound is then saved as a sound file on the a sound file on the computercomputer..

JOYSTICKJOYSTICK Users running game Users running game

software such as a software such as a driving of flight simulator driving of flight simulator may prefer to use a may prefer to use a joystick as their pointing joystick as their pointing device. device.

A A joystickjoystick is a vertical is a vertical lever mounted on a lever mounted on a base. You move the lever base. You move the lever in different direction to in different direction to control the actions of a control the actions of a vehicle or player. The vehicle or player. The lever usually includes lever usually includes buttons called buttons called triggerstriggers that you can press to that you can press to activate certain events. activate certain events.

WHAT IS OUTPUT?WHAT IS OUTPUT? 0utput0utput is data that has been processed is data that has been processed

into a useful form called information. into a useful form called information.

Computers generate several types of Computers generate several types of output, depending on the hardware and output, depending on the hardware and software being used and the requirements software being used and the requirements of the user. You may choose to display or of the user. You may choose to display or view this output on a monitor, print it on a view this output on a monitor, print it on a printer, or listen to it through speakers or printer, or listen to it through speakers or a headset.   a headset.  

OUTPUTOUTPUT

4 COMMON TYPES 4 COMMON TYPES

TEXTTEXTConsists of characters that are used Consists of characters that are used

to create words, sentences, and to create words, sentences, and paragraphs. paragraphs.

A A charactercharacter is a letter, number, is a letter, number, punctuation mark, or any other punctuation mark, or any other symbol that requires one byte of symbol that requires one byte of computer storage space. computer storage space.

GRAPHICSGRAPHICSAre digital representations of non-Are digital representations of non-

text information such as drawings, text information such as drawings, charts, and photographs. Graphics charts, and photographs. Graphics also can be animated, giving them also can be animated, giving them the illusion of motion. the illusion of motion.

AUDIOAUDIO Is music, speech, or any other sound. Is music, speech, or any other sound.

Recall that sound waves, such as the Recall that sound waves, such as the human voice or music, are human voice or music, are analoganalog. .

To store such sounds, a computer To store such sounds, a computer converts the sounds from a continuous converts the sounds from a continuous analog signal into a digital format. Most analog signal into a digital format. Most output devices require that the output devices require that the computer convert the digital format computer convert the digital format back into analog signals. back into analog signals.

VIDEOVIDEO VideoVideo consists of images that are played consists of images that are played

back at speeds that provide the back at speeds that provide the appearance of full motion. appearance of full motion.

Video often is captured with a video Video often is captured with a video input devices such as a camera or VCR. input devices such as a camera or VCR. A video capture card converts an analog A video capture card converts an analog video signal into a digital that a video signal into a digital that a computer can understand. The digital computer can understand. The digital signal then is stored on the computer’s signal then is stored on the computer’s hard disk. hard disk.

OUTPUT DEVICESOUTPUT DEVICESAn An output deviceoutput device is any computer is any computer

component capable of conveying component capable of conveying information to a user. information to a user.

Commonly used output devices Commonly used output devices include include display devices, speakers, display devices, speakers, headset, data projector, facsimile headset, data projector, facsimile machinesmachines and and multifunction devicesmultifunction devices. .    

DATA PROJECTORSDATA PROJECTORS A A data projectordata projector takes the takes the

image that displays on a image that displays on a computer screen and computer screen and projector it into a screen projector it into a screen so that an audience of so that an audience of people can see the image people can see the image clearly. clearly.

Data projectors can be Data projectors can be large devices attached to large devices attached to ceiling or wall in an ceiling or wall in an auditorium, or they can be auditorium, or they can be small portable devices. small portable devices. Two types of smaller, Two types of smaller, lower-cost units are lower-cost units are LCD LCD projectorsprojectors and and DLP DLP projectorsprojectors. .

LIQUID CRYSTAL DISPLAYLIQUID CRYSTAL DISPLAY

An An LCD projectorLCD projector, which uses liquid crystal display , which uses liquid crystal display technology, attaches directly to a computer and uses technology, attaches directly to a computer and uses its own light source to display the information shown its own light source to display the information shown on the computer screen. Because LCD projectors tend on the computer screen. Because LCD projectors tend to produce lower-quality images, some users prefer to to produce lower-quality images, some users prefer to use a DLP projector for shaper, brighter images. use a DLP projector for shaper, brighter images.

A liquid crystal display consists of an array of tiny A liquid crystal display consists of an array of tiny segments (called segments (called pixelspixels) that can be manipulated to ) that can be manipulated to present information. present information.

DIGITAL LIGHT PROCESSING DIGITAL LIGHT PROCESSING (DLP)(DLP)

A A digital light processing (DLP)digital light processing (DLP) projectors projectors uses tiny mirrors to reflect light, producing uses tiny mirrors to reflect light, producing crisp, bright, colorful images that remain crisp, bright, colorful images that remain in focus and can be seen clearly even in a in focus and can be seen clearly even in a well-lit room. well-lit room.

CRT MONITORSCRT MONITORS A A CRT monitorCRT monitor, or monitor is a display , or monitor is a display

device that consists of a screen housed device that consists of a screen housed in a plastic or metal case. in a plastic or metal case.

A A color monitorcolor monitor display text, graphics and display text, graphics and video information in color. Color monitor video information in color. Color monitor are used widely with all types of computers are used widely with all types of computers because most of today’s software is because most of today’s software is designed to display information in color.designed to display information in color.

CRT MONITORS (cont.)CRT MONITORS (cont.) Monitor that display only one color are Monitor that display only one color are

considered monochrome. A considered monochrome. A monochromemonochrome monitor display text, graphics and video monitor display text, graphics and video information in one color (usually white, information in one color (usually white, amber amber or or greengreen) on a black background.) on a black background.

Like a television set, the core of a CRT Like a television set, the core of a CRT monitor is a large glass tube called a monitor is a large glass tube called a cathode ray tube (CRT).cathode ray tube (CRT).

MONITORMONITORThe computer monitor, screen or The computer monitor, screen or

VDUVDU (visual Display Unit (visual Display Unit) is the most ) is the most common output devices. common output devices.

Screen sizes are measured Screen sizes are measured diagonally and are still quoted in diagonally and are still quoted in inches. Larger monitor make working inches. Larger monitor make working at a computer easier on the eyes and at a computer easier on the eyes and are essential for use in are essential for use in DTPDTP (Desktop (Desktop Publishing) and Publishing) and CADCAD work. work.

MONITOR (cont.)MONITOR (cont.) ADVANTAGEADVANTAGE Relatively cheap and reliable, can Relatively cheap and reliable, can

display text and graphics in a wide display text and graphics in a wide range of colors. They are also quiet range of colors. They are also quiet and do not waste paper.and do not waste paper.

DISADVANTAGEDISADVANTAGE No permanent copyNo permanent copy to keep and to keep and

unsuitable for users with visual unsuitable for users with visual problemsproblems. .

GAS PLASMA MONITORS GAS PLASMA MONITORS Gas plasma monitorsGas plasma monitors use gas plasma technology, which use gas plasma technology, which

substitutes a layer of gas the liquid crystal material in an substitutes a layer of gas the liquid crystal material in an LCD monitor. LCD monitor.

When voltage is applied, the gas glows and produces the When voltage is applied, the gas glows and produces the pixels that form an image. Gas plasma monitors offer larger pixels that form an image. Gas plasma monitors offer larger screen sizes and higher display quality than LCD monitors screen sizes and higher display quality than LCD monitors but are much more expensive. but are much more expensive. 

MONITOR QUALITYMONITOR QUALITYThe quality of a monitor’s display depends largely on its:  The quality of a monitor’s display depends largely on its: 

Resolution.Resolution. The resolution or sharpness and clarity, of a monitor are related directly to the The resolution or sharpness and clarity, of a monitor are related directly to the number of pixels it can display. Resolution is expressed as two separate number of pixels it can display. Resolution is expressed as two separate numbers: the number of columns of pixels and the number of rows of pixels a numbers: the number of columns of pixels and the number of rows of pixels a monitor can display. monitor can display.

Dot pitch. Dot pitch. Pitch is a measure of image clarity. The dot pitch is the vertical distance Pitch is a measure of image clarity. The dot pitch is the vertical distance between each pixel on a monitor. The smaller the distance between the between each pixel on a monitor. The smaller the distance between the pixels, the sharper the displayed image. pixels, the sharper the displayed image.

Refresh rate. Refresh rate. A monitor’s refresh rate should be fast enough to maintain a constant, A monitor’s refresh rate should be fast enough to maintain a constant, flicker-free image. A slower refresh rate causes the image to fade and then flicker-free image. A slower refresh rate causes the image to fade and then flicker as it is redrawn, which can headaches for user. Refresh rate is flicker as it is redrawn, which can headaches for user. Refresh rate is measured according to measured according to hertzhertz, which is the number of times per second the , which is the number of times per second the screen is redrawn. screen is redrawn.

HIGH-DEFINITION HIGH-DEFINITION TELEVISIONTELEVISION

High-definition television (HDTV)High-definition television (HDTV) is a type is a type of television set that works with digital of television set that works with digital broadcasting signals and support a wider broadcasting signals and support a wider screen and higher resolution display than screen and higher resolution display than a standard television set. a standard television set.

When you use a standard television set as When you use a standard television set as a monitor for your computer, the output a monitor for your computer, the output must be converted to an analog signal that must be converted to an analog signal that can be displayed by the television set.    can be displayed by the television set.   

PRINTERSPRINTERS PrintersPrinters are primary output are primary output

devices used to generate devices used to generate information from the information from the computers. These output are computers. These output are often referred to as “Hard often referred to as “Hard Copies” or “Printout” in Copies” or “Printout” in computer jargon.computer jargon.

Character printersCharacter printers are the are the slowest printers since they slowest printers since they print character by character. print character by character. There are two types of There are two types of character printers: character printers:

Dot-Matrix printers Dot-Matrix printers

Letter-Quality printersLetter-Quality printers

DOT-MATRIX PRINTER

INK JET PRINTER

LASER PRINTER

TYPES OF PRINTERSTYPES OF PRINTERS DOT-MATRIX PRINTERS DOT-MATRIX PRINTERS Limited to situations where carbon copies are needed and Limited to situations where carbon copies are needed and

the quality is not too important. the quality is not too important. Typical uses might be in warehouse where duplicate Typical uses might be in warehouse where duplicate

copies of orders need to produce quickly and cheaply. copies of orders need to produce quickly and cheaply. The printing quality is low because of this impact these The printing quality is low because of this impact these

printers can be quite noise. printers can be quite noise. The purchase cost is low and the running costs are very The purchase cost is low and the running costs are very

low. low. Can print fairly quickly, if you remember that multiple Can print fairly quickly, if you remember that multiple

copies are being printed in one print run. copies are being printed in one print run. Robust and can operate in harsh environments. Robust and can operate in harsh environments. If several sheets of self-carbonating paper are placed into If several sheets of self-carbonating paper are placed into

the printer then the impact will produce multiple copies. the printer then the impact will produce multiple copies.    

TYPES OF PRINTERSTYPES OF PRINTERS(cont.)(cont.)

INK-JET PRINTINK-JET PRINT A popular choice for home and school use A popular choice for home and school use

where small amounts of printing are where small amounts of printing are done     done    

The ink cartridges can be expensive so The ink cartridges can be expensive so running costs can be high. running costs can be high.

Speed is slow compared to a laser printer.Speed is slow compared to a laser printer. Relatively inexpensive and produce high Relatively inexpensive and produce high

quality black and white or color printing.quality black and white or color printing.

TYPES OF PRINTERSTYPES OF PRINTERS(cont.)(cont.)

LASER PRINTERSLASER PRINTERS Common wherever fast, high quality printing is Common wherever fast, high quality printing is

required. required. Non color laser printers are more expensive than Non color laser printers are more expensive than

ink-jet printers (but the difference is narrowing). ink-jet printers (but the difference is narrowing). Color laser printers are ‘considerably more Color laser printers are ‘considerably more

expensive’ (but their speed and high quality expensive’ (but their speed and high quality output means they are becoming more popular). output means they are becoming more popular).

Quiet and fast and produce high quality printouts. Quiet and fast and produce high quality printouts.

Running cost are low because although toner Running cost are low because although toner cartridges are expensive to replace, they last a cartridges are expensive to replace, they last a long time.long time.

SPEAKER SPEAKER A system's A system's speaker speaker

is the component is the component that takes the that takes the electronic signal electronic signal stored on things stored on things like CDS, Tapes, like CDS, Tapes, and DVDs and and DVDs and turns it back into turns it back into actual sound that actual sound that we can hear. we can hear.

PLOTTERPLOTTER

A device that draws pictures on paper A device that draws pictures on paper based on commands from computer. based on commands from computer.

Plotter Plotter differs from printer in that they differs from printer in that they draw lines using a pen. Multicolor draw lines using a pen. Multicolor plotter use different colored pens to plotter use different colored pens to draw different colors.   draw different colors.  

FACSIMILE (FAX) MACHINE FACSIMILE (FAX) MACHINE A A facsimile (fax) machinefacsimile (fax) machine is a device that is a device that

transmits and receives documents transmits and receives documents over telephone lines. The documents can over telephone lines. The documents can contain text, drawings, or photographs, or contain text, drawings, or photographs, or can be handwritten. can be handwritten.

When sent or received via a fax machine, When sent or received via a fax machine, these documents are known as these documents are known as faxesfaxes. .

WHAT IS STORAGE?WHAT IS STORAGE? StorageStorage also called also called secondary storage, secondary storage,

auxiliary storage,auxiliary storage, or or mass storagemass storage. Holds . Holds items such as data, instruction, and items such as data, instruction, and information for future use. information for future use.

Think of storage as a filling cabinet used to Think of storage as a filling cabinet used to hold file folder, and memory as the top of hold file folder, and memory as the top of your desk. When you need to work with a your desk. When you need to work with a file, you remove it from the filling cabinet file, you remove it from the filling cabinet (storage) and place it on your desk (storage) and place it on your desk (memory). When you are finished with the (memory). When you are finished with the file, you return it to the filling cabinet file, you return it to the filling cabinet (storage). (storage).

WHAT IS STORAGE? (cont.)WHAT IS STORAGE? (cont.) Storage devices can function as sources of Storage devices can function as sources of

input and output. input and output. For example, each time a storage devices For example, each time a storage devices

transfer data, instruction, and information transfer data, instruction, and information from a storage medium into memory-a from a storage medium into memory-a process calledprocess called reading-it functionreading-it function as an as an input source. input source.

When a storage device transfer these item When a storage device transfer these item from memory to a storage medium-a from memory to a storage medium-a process called process called writing-writing-it functionit function as an as an output source. output source.

WHAT IS STORAGE? (cont.)WHAT IS STORAGE? (cont.)

The size, orThe size, or capacitycapacity, of storage , of storage devices, is measured by the number devices, is measured by the number of of bytesbytes (characters). For example, a (characters). For example, a typical floppy disk can store 1.44 MB typical floppy disk can store 1.44 MB of data (approximately 1,440,000 of data (approximately 1,440,000 bytes) and a typical hard disk can bytes) and a typical hard disk can store 8GB of data (approximately store 8GB of data (approximately 8,000,000,000 bytes). 8,000,000,000 bytes).

MEMORYMEMORY MemoryMemory, which is composed of one or more , which is composed of one or more

chips on the motherboard, holds data and chips on the motherboard, holds data and instruction while the CPU is processing them. instruction while the CPU is processing them.

The The two basic type of memorytwo basic type of memory are volatile and are volatile and nonvolatile. The contents of nonvolatile. The contents of volatile memoryvolatile memory, , such as RAM are lost (erased) when the power such as RAM are lost (erased) when the power to the computer is turned of. The contents of to the computer is turned of. The contents of nonvolatile memorynonvolatile memory, however, are not lost , however, are not lost when power is removed from the computer. For when power is removed from the computer. For example, once instruction has been record onto example, once instruction has been record onto a nonvolatile ROM chip, they usually cannot be a nonvolatile ROM chip, they usually cannot be erased or change, and the contents of the chips erased or change, and the contents of the chips are not erased when power is turned off. are not erased when power is turned off. 

FLOPPY DISKFLOPPY DISK A A floppy diskfloppy disk, or , or

diskettediskette, is a portable, , is a portable, inexpensive storage inexpensive storage medium that consists of a medium that consists of a thin, circular, flexible thin, circular, flexible plastic disk with a plastic disk with a magnetic coating enclosed magnetic coating enclosed in a square-shaped plastic in a square-shaped plastic shell). shell).

In the early 1970s, IBM introduced the floppy In the early 1970s, IBM introduced the floppy disk a new type or storage. Because these early disk a new type or storage. Because these early 8-inch wide disk had flexible plastic cover, 8-inch wide disk had flexible plastic cover, many users referred to them as floppies. The many users referred to them as floppies. The next generation of floppies looked much the next generation of floppies looked much the same, but was only 5.25-inches wide. Today, same, but was only 5.25-inches wide. Today, the most widely used floppy disk is 3.5-inches the most widely used floppy disk is 3.5-inches wide. The flexible cover of the earlier floppy wide. The flexible cover of the earlier floppy disk has been replaced with a rigid plastic outer disk has been replaced with a rigid plastic outer cover. Thus, although today’s 3-5 inches disk cover. Thus, although today’s 3-5 inches disk are not at all floppy. The term floppy disk still are not at all floppy. The term floppy disk still used. used.

CHARACTERISTICS OF A CHARACTERISTICS OF A FLOPPY DISKFLOPPY DISK

To protect them from accidentally To protect them from accidentally being erased, floppy disk have a being erased, floppy disk have a write-protect notch. write-protect notch.

A A write-protect notchwrite-protect notch is a small is a small opening in the corner of the floppy opening in the corner of the floppy disk with a tab that you slide to cover disk with a tab that you slide to cover or expose the notch. or expose the notch.

CHARACTERISTICS OF A FLOPPY CHARACTERISTICS OF A FLOPPY DISKDISK

(cont.)(cont.) On a floppy disk, if the write protect notch is On a floppy disk, if the write protect notch is

exposed, or open, the drive cannot write on exposed, or open, the drive cannot write on the floppy disk. If the write-protect north is the floppy disk. If the write-protect north is covered, or closed, the drive can write on covered, or closed, the drive can write on the floppy disk. The write protect notch only the floppy disk. The write protect notch only affect the flopper disk drive’s capability of affect the flopper disk drive’s capability of writing on the disk: a floppy disk drive car writing on the disk: a floppy disk drive car read from the floppy disk whether the write-read from the floppy disk whether the write-protect notch is open or closed. Some floppy protect notch is open or closed. Some floppy disk has a second opening on the opposite disk has a second opening on the opposite side of disk that does not have the small side of disk that does not have the small tab: this opening identifies the disk as a tab: this opening identifies the disk as a high-density floppy disk.high-density floppy disk.

FLOPPY DISK DRIVEFLOPPY DISK DRIVE AA floppy disk drivefloppy disk drive (FDD) (FDD) is a device that can read from is a device that can read from

and write on a floppy disk. Desktop personnel computers and write on a floppy disk. Desktop personnel computers usually have a floppy disk drive installed inside the system usually have a floppy disk drive installed inside the system unit.unit.

Floppy disk drive is Floppy disk drive is downward compatibledownward compatible, which means , which means they recognize and can use earlier media. Floppy disk drive they recognize and can use earlier media. Floppy disk drive is not is not upward compatibleupward compatible, however, which means they , however, which means they cannot recognize newer media. For example, a lower-cannot recognize newer media. For example, a lower-density floppy disk drive cannot read from or write on a density floppy disk drive cannot read from or write on a high-density floppy disk. high-density floppy disk.

FLOPPY DISK DRIVEFLOPPY DISK DRIVE(cont.)(cont.)

On any 3.5-inch floppy disk, a piece of metal called On any 3.5-inch floppy disk, a piece of metal called the the shuttershutter covers an opening in the rigid plastic covers an opening in the rigid plastic shell. When you insert a floppy disk into a floppy shell. When you insert a floppy disk into a floppy disk drive, the drives slides shutter to the side to disk drive, the drives slides shutter to the side to expose a portion of both sides of the floppy disk’s expose a portion of both sides of the floppy disk’s recording surface. recording surface.

The The read/write headread/write head is the mechanism that is the mechanism that actually read items from a write items on the floppy actually read items from a write items on the floppy disk. Figure 6-0 illustrates the steps for reading disk. Figure 6-0 illustrates the steps for reading from and writing on a floppy disk. The average from and writing on a floppy disk. The average access time for current floppy disk drives to locate access time for current floppy disk drives to locate an item on the disk is 84 ms, or approximately 1/12 an item on the disk is 84 ms, or approximately 1/12 of a second. of a second.

HARD DISKHARD DISK A A hard diskhard disk usually consist of several usually consist of several

inflexible, circular disk, called platter, on inflexible, circular disk, called platter, on which item are stored electronically. which item are stored electronically.

The hard disk in most desktop personnel The hard disk in most desktop personnel computer is housed inside the system computer is housed inside the system unit. Such hard disk, which are not unit. Such hard disk, which are not portable, are considered portable, are considered fixed disk.fixed disk.

A A platter platter in a hard disk is made of in a hard disk is made of aluminum, glass, or ceramic and is coated aluminum, glass, or ceramic and is coated with a material that allow item to be with a material that allow item to be magnetically recorded on it surface. On magnetically recorded on it surface. On hard disk, the platter, the read/write hard disk, the platter, the read/write heads, and the mechanism for moving the heads, and the mechanism for moving the heads across the surface of the disk heads across the surface of the disk enclosed in a airtight, sealed case that enclosed in a airtight, sealed case that protect the platters from contamination.protect the platters from contamination.

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