2 Objectives of this chapter: You can…Define input and outputList the characteristics of input and output devicesDescribe the components of a processor and how they complete a machine cycleDifferentiate among the various types of memoryDifferentiate between storage devices and storage media
3 Overview This chapter covers Input Device Output Device Central Unit Processing (CPU)Memory UnitStorageCommunicationsGO!
5 Introduction What is computer hardware? Computer devices in physical formComprised of 4 components:Input devicesCentral Processing Unit (CPU)Output devicesMemory
6 Introduction (cont’d) ProcessorControl UnitArithmetic Logic Unit (ALU)Control UnitArithmetic Logic Unit (ALU)Instructions Data InformationMemoryInput DevicesDataInformationOutput DevicesInstructions Data InformationStorage Devices
7 Introduction (cont’d) Bit and bytesBit (Binary Digit) is the basic unit of information in computers1 bit = 0 or 1 Computer binary systemRefers to transfer rate per secondKilobyte, megabyte, gigabyte, and terabyte are terms that describe large units of data used in measuring data storageExample: 100 GB hard drive8 bits = 1 Byte1024 Bytes = 1 Kilobyte (KB)1,048,576 Bytes = 1 Megabyte (MB)1,043,741,824 Bytes = 1 Gigabyte (GB)1,099,511,627,776 Bytes = 1 Terabyte (TB)
13 Input Device (cont’d) Pointing Device Pointing device controls movement of pointer, also called mouse pointermouse buttonsmouse padballwheel buttonMousePointing device that fits underpalm of handMechanical mouse has rubber or metal ball on underside
14 Input Device (cont’d) Pointing Device (cont’d) Optical mouse No moving mechanical parts insideSenses light to detect mouse’s movementMore precise than mechanical mouseConnects using a cable, or wireless
15 Input Device (cont’d) Pointing Device (cont’d) Trackball Stationary pointing device with a ball on its top or sideTo move pointer, rotate ball with thumb, fingers, or palm of hand
16 Input Device (cont’d) Pointing Device (cont’d) Touchpad and a pointing stickTouchpad is small, flat, rectangular pointing device sensitive to pressure and motionPointing stick is pointing device shaped like pencil eraser positioned between keys on keyboard
17 Input Device (cont’d) Pointing Device (cont’d) Joystick and a wheel Joystick is vertical lever mounted on a baseWheel is steering-wheel-type input devicePedal simulates car brakes and accelerator
18 Input Device (cont’d) Pointing Device (cont’d) Touch screen Touch areas of screen with fingerOften used with kiosks
19 Input Device (cont’d) Sound and voice input MIDI (musical instrument digital interface)External device, such aselectronic piano keyboard,to input music and soundeffectsMicrophoneAllow user to input theirvoice
20 Input Device (cont’d) Video input Process of entering full-motion images into computerVideo capture card is adapter card that converts analog video signal into digital signal that computer can useDigital video (DV) camera records video as digital signals
21 Input Device (cont’d) Scanner FlatbedLight-sensing device that reads printed text and graphicsUsed for image processing, converting paper documents into electronic imagesPen or HandheldFlatbed scanner – design to scan flat objectsHandheld scanner – capture small amounts of textSheet-fed scanner – scan one flat document at a timeSheet-fedDrum
22 Input Device (cont’d) How does a flatbed scanner work? Step 1: Place the document to be scanned face down on the glass window. Using buttons on the scanner or the scanner program, start the scanning process.Step 2:The scanner converts the document content to digital information, which is transmitted through the cable to thememory of the computer.Step 3: Once in the memory of the computer, users can display the image, print it, it, include it in a document, or place it on a Web page.
23 Input Device (cont’d) Readers Barcode Readers Optical Mark Readers (OMR)Radio frequency Identification (RFID) ReadersOptical Character Recognition (OCR) DevicesMagnetic Ink Character Recognition (MICR) ReadersBiometric Readers
25 Output Device What is output? Data that has been processed into a useful form,Output device is any hardware component that can convey information to user
26 Output Devices (cont’d) Display deviceOutput device that visually conveys informationInformation on display device sometimes called soft copyMonitor houses display device as separate peripheral
27 Output Devices (cont’d) Display deviceLCD monitorUses liquid crystal displayHave a small footprintMobile devices that contain LCD displays includeNotebook computer, Tablet PC, PDA, and Smart Phone
28 Output Device (cont’d) How does LCD work?Uses liquid compound to present information on a displayStep 2. As light passes through liquid crystal, electrical charge causes some of the cells to twist, making light waves bend as they pass through color filter.Step 1. Panel of fluorescent tubes emits light waves through polarizing glass filter, which guides light toward layer of liquid crystal cells.Liquid crystal cellsStep 3. When light reaches second polarizing glass filter, light is allowed to pass through any cells that line up at the first polarizing glass filter. Absence and presence of colored light cause image to display on the screen.Transparent electrodesAlignment layerPolarizing glass filterFluorescent tube panelColor filter
29 Output Device (cont’d) Display devicePlasma monitorDisplays image by applying voltage to layer of gasLarger screen size and higher display quality than LCD, but are more expensivep. 306 Fig. 6-7
30 Output Device (cont’d) Display deviceCRT monitorContains cathode-ray tube (CRT)Screen coated with tiny dots of phosphor materialEach dot consists of a red, blue, and green phosphorCommon sizes are 15, 17, 19, 21, and 22 inchesViewable size is diagonal measurement of actual viewing area
31 Output Device (cont’d) PrinterportraitlandscapeOutput device that produces text and graphics on a physical mediumResult is hard copy, or printoutTwo orientations: portrait and landscape
32 Output Device (cont’d) How do you know which printer to buy?Depends on printing needsBudgetSpeedColor or black and whiteCost per pageMultiple copiesGraphics and photo printingPaper types and sizesSystem compatibilityFuture needsWireless capability
33 Output Device (cont’d) PrinterTwo basic types:ImpactNon-impact300 dpi600 dpi1200 dpiWhat is the resolution of aprinter?Sharpness and clarityMeasured by number ofdots per inch (dpi) printercan output
34 Output Device (cont’d) Impact printerCharacters/graphics are formed on the paper by physical striking contact between ink ribbon and paperExamples aredot-matrix printer (continuous paper),line printer (mainframe/minicomputer)
35 Output Device (cont’d) Nonimpact printerForms characters and graphics without striking paperInk-jet printersprays tiny drops of liquid ink onto paperPrints in black-and-white or color on a variety of paper types
36 Output Device (cont’d) Photo printerColor printer that produces photo-lab-quality picturesMany photo printers have a built-in card slot
37 Output Device (cont’d) Laser printerHigh-speed, high-quality nonimpact printerPrints text and graphics in very high-quality resolution, ranging from 1,200 to 2,400 dpiTypically costs more than ink-jet printer, but is much faster
38 Output Device (cont’d) Thermal printerGenerates images by pushing electrically heated pins against heat-sensitive paperDye-sublimation printer (also called a digital photo printer) uses heat to transfer dye to specially coated paper
39 Output Device (cont’d) Mobile printerSmall, lightweight, battery-powered printer that allows mobile user to print from notebook computer, Tablet PC, or PDA while traveling
40 Output Device (cont’d) Label printers and Postage printersSmall printer that prints on adhesive-type materialMost also print bar codesPostage printer has built-in digital scale and prints postage stamps
41 Output Device (cont’d) PlotterSophisticated printer used to produce high-quality drawingsLarge-format printer creates photo-realistic-quality color prints
42 Output Device (cont’d) Audio output deviceComputer component that produces music, speech, or other soundsSpeakers and headsets are common devices
43 Output device (cont’d) Data projectorDevice that takes image from computer screen and projects it onto larger screen
44 Output Device (cont’d) Force feedbackSends resistance to joystick or wheel in response to actions of user
46 Arithmetic Logic Unit (ALU) CPUWhat is the central processing unit (CPU)?Also called the processorInterprets and carries out basic instructions that operate a computerProcessorControl UnitArithmetic Logic Unit (ALU)Control UnitArithmetic Logic Unit (ALU)Control unit directs and coordinates operations in computerArithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations
47 CPU (cont’d) Machine cycle Four operations of the CPU comprise a machine cycleStep 1. Fetch Obtain program instruction or data item from memoryProcessorControl UnitMemoryALUStep 2. Decode Translate instruction into commandsStep 4. Store Write result to memoryStep 3. Execute Carry out command
48 CPU (cont’d)RegisterTemporary high-speed storage area that holds data and instructionsStores location from where instruction was fetchedStores instruction while it is being decodedStores data while ALU computes itStores results of calculation
49 Each tick is a clock cycle Pace of system clock is clock speed CPU (cont’d)System clockControls timing of all computer operationsGenerates regular electronic pulses, or ticks, that set operating pace of components of system unitEach tick is a clock cyclePace of system clock is clock speedMost clock speeds are in the gigahertz (GHz) range (1 GHz = one billion ticks of system clock per second)Processor speed can also be measured in millions of instructions per second (MIPS)
50 CPU (cont’d) Parallel processing Control ProcessorParallel processingUsing multiple processors simultaneously to execute a program fasterRequires special software to divide problem and bring results togetherProcessor 1MemoryProcessor 2MemoryProcessor 3MemoryProcessor 4MemoryResults combined
52 Overview Representation of characters using codes Other data types – audio, graphic, video representation
53 Introduction Human brain can process large variety of data including : CharacterNumbersImage and soundTouch, smell and taste.Current technology limits data that computer can efficiently manipulate to numeric data. Therefore, ALL data - no matter how complex - must be represented (encoded) in the computers memory in numeric form
54 Introduction (cont’d) Computers represent data using binary numbers because:It is easy to represent binary numbers as electrical states or signals which can be processed by two-state (on-off) electrical devices (eg transistors)It is easy to represent binary numbers as electrical signals for moving between system components.
55 Introduction (cont’d) Goals of computer data representation:Compactness - compact data representation requires less storage space and less expensive processing and storage devices.Accuracy - the accuracy of representation increases with the number of data bits used.Range – routine calculations can generate quantities that are either too large or too small to be stored within finite circuitry.
56 Introduction (cont’d) Ease of manipulation - the efficiency of a processor depends on its complexity.Standardization - various organizations have created standard data encoding methods for communication among computer systems and their components.Some standards evolve from proprietary products which become very popular. eg?
57 Data typeCPU will have instructions for dealing with limited no of data types (primitives), based on these goals of data representation. Usually these types are:CharBoolean (T/F)IntegerRealMemory addresses
58 Alphanumeric Codes There are three main coding methods in use: ASCII EBCDICUnicode.7-bit code (128 characters)Has an extended 8-bit versionUsed on PC’s and non-IBM mainframesWas widely used transfer data from one computer to another- now being replaced by Unicode.ASCII coding Examples (refer text book)
59 Alphanumeric Codes (cont’d) EBCDIC8-bit code (256 characters)Used on mainframe IBM machines.Both ASCII and EBCDIC are 8-bit codes inadequate for representing all international characters.Eg. Chinese charactersUnicode recent 16 bit standart- can represent 65 thousand characters, of which 49,000 have been defined, incorporates ASCII-7 as subset.
60 Alphanumeric Codes (cont’d) UnicodeUnicode recent 16 bit standard- can represent 65 thousand characters, of which 49,000 have been defined, incorporates ASCII-7 as subset.Need to represent many more data types that text.Eg. Graphics, sound and video.Need STANDARD ways to do this enable exchanging/sharing data.Standard maybe created by official Industry committees or may be adopted from a commercial product in widespread use.Many data types such as images and sound require large no of bits to encode data compression required for storage and transmission.
61 Binary SystemUsing On/Off Electrical States to Represent Data & InstructionsThe binary system has only two digits - 0 and 1Bit - binary digitByte - group of 8 bits used to represent one character, digit, or other value
62 The Binary System: Using On/Off Electrical States to Represent Data & Instructions ASCII (American Standard Code for Information Interchange) – the binary code most widely used with microcomputersEBCDIC (Extended Binary Coded Decimal Interchange Code) - used with large computersUnicode - uses two bytes for each character rather than one byte (8 bits)
63 Data CompressionData compression software uses algorithms to reduce total no bits transmitted. Saves storage or bandwidth but uses CPU resources.Two types - lossy and losslessLossless where original data restored exactly e.g. documents, accounting records, executable programsLossy where some reduction in data quality acceptable - e.g. images/video /sound
64 Image DataTwo main categories of images - bit map images and object imagesBit map images (eg photos, paintings) have a definition for each individual point making up the image (pixel)Object images have a set of mathematical definitions which describe the object(s) making up the image and their position within image
65 Bit MapsA number of different bit map data formats exist - eg .gif, .bmp, jpegBit maps can require large amounts of memory, eg 800 * 600 image has 480,000 pixels. Using 24 bit colour, image requires 1.44 MB storage.Some formats include data compression to reduce file size. Eg GIF uses data compression algorithm called LZW.
66 Object ImageObject images generally more compact and lend themselves to more complex manipulation.Must be converted to bitmaps for display or printing (e.g. postscript printer)Images are made up of lines, curves, which can be mathematically defined and filled with colors/patterns.Manipulation of image does not result in loss of detail
67 Audio DataSound waves are analog. In order to be stored and manipulated by computer, they must be converted to digital form.Frequent sampling of the wave (and large sample size) ensures good quality reproduction but produces large sound files, as in standard .wav filesSpecialized hardware (sound cards) required for good quality sound (perform 2 way conversions)
68 MP3Other standard file formats such as MP3 and .midi work differently -much smallerMP3 is audio part of MPEG (Motion Picture Experts Group) standard, and uses a lossy compression algorithm.
69 Video DataConsists of sound and images (frames) which must be sampled and converted to digital format.Uncompressed video data very large. Eg 60 minutes of DV-AVI video files (v. high quality) ~ 12GBStandard formats MPEG, include data compression. Eg High quality MPEG-2 format, 2 hours on single DVD disc (4.7GB).Video conferencing performance using any standard still poor due to bandwidth problems over data communications links.
71 Memory Unit Memory consists of electronic components that store: instructions waiting to be executed by the processordata needed by those instructionsResults of the processed data (information)In short, it stores 3 types of items:OS and other system softwareApplication programsData being processed and the result (info)
72 Memory Unit (cont’d) RAM & ROM Cache Registers Cheapest Fastest Disks, CD-ROM, Tapes
73 Memory Unit (cont’d) How is memory measured? By number of bytes available for storageTerm Abbreviation Approximate SizeKilobyte KB or K 1 thousand bytesMegabyte MB 1 million bytesGigabyte GB 1 billion bytesTerabyte TB 1 trillion bytes
74 Memory Unit (cont’d) Random Access Memory (RAM)? Memory chips that can be read from and written to by processorAlso called main memory or primary storageMost RAM is volatile, it is lost when computer’s power is turned offThe more RAM a computer has, the faster it responds
75 Memory Unit (cont’d)How do program instructions transfer in and out of RAM?Step 1. When you start the computer, certain operating system files are loaded into RAM from the hard disk. The operating system displays the user interface on the screen.Operating system instructionsRAMOperating system interfaceStep 2. When you start a word processing program, the program’s instructions are loaded into RAM from the hard disk. The word processing program and certain operating system instructions are in RAM. The word processing program window is displayed on the screen.Word processing program instructionsWord processing program windowRAMStep 3. When you quit a program, such as the word processing program, its program instructions are removed from RAM. The word processing program is no longer displayed on the screen.Word processing program instructions are removed from RAMWord processing program window is no longer displayed on desktop
76 Memory Unit (cont’d) Static RAM (SRAM) Dynamic RAM (DRAM) Two basic types of RAM chipsMost common typeDo not have to be re-energized as often as DRAMDynamic RAM (DRAM)Static RAM (SRAM)Must be re-energized constantlyFaster and more reliable than DRAM chipsNewer Type: Magnetoresistive RAM (MRAM)
77 Memory Unit (cont’d) Where does memory reside? dual inline memory moduleWhere does memory reside?Resides on small circuit board called memory moduleMemory slots on motherboard hold memory modulesmemory slotmemory chip
78 Memory Unit (cont’d) How much RAM do you need? Depends on type of applications you intend to run on your computerRAMUse256 MB to 1 GB512 MB to 2 GB2 GB and upHome and business users managing personal financeUsing standard application software such as word processingUsing educational or entertainment CD-ROMsCommunicating with others on the WebUsers requiring more advanced multimedia capabilitiesRunning number-intensive accounting, financial, or spreadsheet programsUsing voice recognitionWorking with videos, music, and digital imagingCreating Web sitesParticipating in video conferencesPlaying Internet gamesPower users creating professional Web sitesRunning sophisticated CAD, 3D design, or other graphics-intensive software
79 Memory Unit (cont’d) Cache Helps speed computer processes by storing frequently used instructions and dataAlso called memory cacheL1 cache built into processorL2 cache slower but has larger capacityL2 advanced transfer cache is faster, built directly on processor chipL3 cache is separate from processor chip on motherboard (L3 is only on computers that use L2 advanced transfer cache)
80 Memory Unit (cont’d) Read-only memory (ROM) Memory chips that store permanent data and instructionsNonvolatile memory, it is not lost when computer’s power is turned offThree types:Firmware— Manufactured with permanently written data, instructions, or informationEEPROM (electrically erasable programmable read-only memory)— Type of PROM containing microcode programmer can erasePROM (programmable read-only memory)— Blank ROM chip onto which a programmer can write permanently
81 Memory Unit (cont’d) Flash memory Nonvolatile memory that can be erased electronically and rewrittenUsed with PDAs, smart phones, printers, digital cameras, automotive devices, audio players, digital vocie recorders, and pagersStep 3. Plug the headphones into the MP3 player, push a button on the MP3 player, and listen to the music through the headphones.flash memory chipsUSB portStep 1. Purchase and download MP3 music tracks from a Web site. With one end of a special cable connected to the system unit, connect the other end into the MP3 player.MP3 PlayerStep 2. Instruct the computer to copy the MP3 music track to the flash memory chip in the MP3 player.
82 Memory Unit (cont’d) CMOS Complementary metal-oxide semiconductor memoryUsed in some RAM chips, flash memory chips, and other types of memory chipsUses battery power to retain information when other power is turned offStores date, time, and computer’s startup information
83 Memory Unit (cont’d) What is access time? Amount of time it takes processor to read data from memoryMeasured in nanoseconds (ns), one billionth of a secondIt takes 1/10 of a second to blink your eye; a computer can perform up to 10 million operations in same amount of timeTerm SpeedMillisecond One-thousandth of a secondMicrosecond One-millionth of a secondNanosecond One-billionth of a secondPicosecond One-trillionth of a second
85 PortsMany I/O devices connect into bus via standard interface called a port. An I/O port is a connector at end of bus into which device can be plugged.Older I/O ports were low speed, still in limited useSerial (e.g. RS-232, 25 pin tech. spec, used for mouse, modem, network interface) one bit at a time, over one line.Parallel (e.g. Centronics, used for printers) multiple bits at a time, over multiple lines.Newer ports, e.g. USB port handle multiple devices and much higher data throughput
86 Ports (cont’d)A port is a connecting socket or jack on the outside of the system unit into which are plugged different kinds of cables.Serial port - sends bits one at a time, one after anotherParallel portSCSI portUSB portFireWire portDedicated portInfrared port
87 Ports (cont’d) Serial port Parallel port - transmits 8 bits simultaneouslySCSI portUSB portFireWire portDedicated portInfrared portThe back of a Macintosh machine
88 Ports (cont’d) Serial port Parallel port SCSI port - allows data to be transmitted in a “daisy chain” to up to 7 devicesUSB portFireWire portDedicated portInfrared port
89 Ports (cont’d) Serial port Parallel port SCSI port USB port - can theoretically connect up to 127 peripheral devices daisy-chained to one general-purpose portFireWire portDedicated portInfrared portUSB port and connector
90 Ports (cont’d) Serial port Parallel port SCSI port USB port FireWire port – for camcorders, DVD players, and TVsDedicated portInfrared port
91 Dedicated ports: mouse port, modem port, and keyboard port Ports (cont’d)Serial portParallel portSCSI portUSB portFireWire portDedicated port - special-purpose portsInfrared portDedicated ports: mouse port, modem port, and keyboard port
92 Ports (cont’d) Serial port Parallel port SCSI port USB FireWire port Dedicated portInfrared port - allows a computer to make a cableless connection with infrared-capable devices
94 Bus A pathway which is associate 3 computer components Consists of 3 types:Data BUSTransmits data/instructions to & from the different componentsAddress BUStransmit the signals that specify locations in memoryControl BUSCarries control signals data and address in data bus and address bus to make sure that the data traffic flows smoothly.
95 Bus (cont’d)Data travels between components (CPU, memory & I/O devices) of the computer along communication paths called buses. (Note: can also have buses external to system)Bus is made up of multiple lines, which may be wires or conductors on a printed board.Bus may carry data between two components only (point-to-point) or it may be shared between many (multipoint). System bus connects CPU with main memory & other system components.
97 How Data is Organized?Data storage hierarchyCharacters: a letter, number or special charactersField: a unit of data consisting of one or more characters (bytes)Record: collection of related fieldsFile: collection of related recordsDatabase: an organized collection of integrated files
98 Data Access MethodSequential vs. direct accessSequential storage: data is stored and retrieved in sequenceE.g. Magnetic tapeSlow but cheaperDirect access storage: the computer can go directly to the information that you wantE.g. CDFast but expensive(1)complexity in maintaining file allocation table(2)need to use hard-disc technology
100 Storage Holds data, instructions, and information for future use Storage medium is physical material used for storageAlso called secondary storage
101 Storage (cont’d)What is a storage device?Hardware that records and retrieves items to and from storage mediaReadingProcess of transferring items from storage media to memoryWritingProcess of transferring items from memory to storage mediaFunctions as source of inputCreates output
102 Storage (cont’d) Magnetic tapes Diskettes Sequential access to data Suitable for small/medium size storage that are not accessed frequentlyUsed for backup and long-term storageDiskettesDirect access to dataUse magnetic diskConsists of track, sector and cluster
103 Storage (cont’d) Hard Disk Optical Disc Direct accessFaster than diskettes because faster spinning rateOptical DiscExample CD-ROMHigh capacity dataStorage Area Network/File ServerHard Drive – storage
104 Storage (cont’d) Why is storage necessary? Retain data when the computer is turned offAre cheaper than memoryPlay an important role during startupAre needed for output