bit, Byte, Kilobyte

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Iniciação à informática, em inglês

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bit, Byte, Kilobyte

  1. 1. Computers AreYour Future© 2006 Prentice-Hall, Inc.
  2. 2. © 2006 Prentice-Hall, Inc Slide 2Computers Are Your Future Chapter 6Computers Are Your FutureChapter 6Inside the System Unit
  3. 3. © 2006 Prentice-Hall, Inc Slide 3Computers Are Your Future Chapter 6What You Will Learn . . .Understand how computers represent dataUnderstand the measurements used to describe datatransfer rates and data storage capacityList the components inside the system unitList the components on the motherboardHow a CPU processes data
  4. 4. © 2006 Prentice-Hall, Inc Slide 4Computers Are Your Future Chapter 6What You Will Learn . . .Factors that determine a microprocessorsperformanceThe types and purpose of memory in a computersystemThe physical connectors on the exterior of the systemunit
  5. 5. © 2006 Prentice-Hall, Inc Slide 5Computers Are Your Future Chapter 6Describing Hardware PerformanceHardware performance refers to the amount of data acomputer can store and how fast it can process thedataMach SpeedSocket 478ATXMotherboardIntel Pentium 42.4Ghz Processor80 GB7200 RPMHard Drive512 MBDDR SDRAMMemory ModuleSystem Case
  6. 6. © 2006 Prentice-Hall, Inc Slide 6Computers Are Your Future Chapter 6OFFON0 1OR = 1 bit100 0 001 10 0 0 01 1OR= 1 Byte= 1 ByteOFF00How Computers Represent DataBit (Binary digit) – On or off state of electric current;considered the basic unit of information; represented by 1s and0s (binary numbers)Byte – Eight bits grouped together to represent a character (analphabetical letter, a number, or a punctuation symbol); 256different combinationsON
  7. 7. © 2006 Prentice-Hall, Inc Slide 7Computers Are Your Future Chapter 61000 bits = 1 kilobit (kb)1,000,000 bits = 1 megabit (mb)1,000,000,000 bits = 1 gigabit (gb)BitsKilobits per second (Kbps), megabits per second(Mbps), and gigabits per second (Gbps) are termsthat describe units of data used in measuring datatransfer rates Example: 56 Kbps modem
  8. 8. © 2006 Prentice-Hall, Inc Slide 8Computers Are Your Future Chapter 68 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)BytesKilobyte, megabyte, gigabyte, and terabyte areterms that describe large units of data used inmeasuring data storageExample: 20 GB hard drive
  9. 9. © 2006 Prentice-Hall, Inc Slide 9Computers Are Your Future Chapter 60 10 0 001 1= 4= 4Representing Characters: Character CodesCharacter codes translate numerical data into charactersreadable by humans American Standard Code for Information Interchange(ASCII) – Eight bits equals one character; used byminicomputers and personal computers Extended Binary Coded Decimal Interchange Code(EBCDIC) – Eight bits equals one character; used by mainframecomputers Unicode – Sixteen bits equals one character; over 65,000combinations; used for foreign language symbolsASCII0 001 11 1 1EBCDIC
  10. 10. © 2006 Prentice-Hall, Inc Slide 10Computers Are Your Future Chapter 6ASCII and EBCDIC Code
  11. 11. © 2006 Prentice-Hall, Inc Slide 11Computers Are Your Future Chapter 6The System UnitThe system unit is a boxlike case that houses the computer’smain hardware componentsA footprint is the space taken up on the desk by the computerForm factor refers to the way the internal components aremounted in the unit
  12. 12. © 2006 Prentice-Hall, Inc Slide 12Computers Are Your Future Chapter 6DesktopNotebookPersonal DigitalAssistantTypes of System Units
  13. 13. © 2006 Prentice-Hall, Inc Slide 13Computers Are Your Future Chapter 6Inside the System UnitMotherboard (mainboard) – Largeprinted circuit board with thousands ofelectrical circuitsPower supply – Transformsalternating current (AC) from walloutlets to direct current (DC) neededby the computerCooling fan – Keeps the system unitcoolInternal Speaker – Used for beepswhen errors are encounteredDrive bays – Housing for thecomputer’s hard drive, floppy drive,and CD-ROM / DVD-ROM drives
  14. 14. © 2006 Prentice-Hall, Inc Slide 14Computers Are Your Future Chapter 6The Motherboard The motherboard provides thecentralized connection pointfor the computer’s componentsMost components areintegrated circuits (chips) Chips carry electrical currentand contain electronicswitches or transistors
  15. 15. © 2006 Prentice-Hall, Inc Slide 15Computers Are Your Future Chapter 6The Central Processing Unit:The MicroprocessorCPUCPU socket Central processing unit (CPU) – A microprocessor thatinterprets and carries out instructions given by software. Itcontrols the computer’s components
  16. 16. © 2006 Prentice-Hall, Inc Slide 16Computers Are Your Future Chapter 6Components of the CPUControl unit – Coordinates and controls all parts ofthe computer systemArithmetic-logic unit – Performs arithmetic orlogical operationsRegisters – Temporarily store the most frequentlyused instructions and data
  17. 17. © 2006 Prentice-Hall, Inc Slide 17Computers Are Your Future Chapter 6The Control UnitThe control unit manages four basic operations (fetch,decode, execute, and write-back)The four-step process is known as the machine cycle orprocessing cycleThe processing cycle consists of two phases: Instruction Cycle– Fetch – Gets the next program instruction from the computer’smemory– Decode – Figures out what the program is telling the computer todo Execution Cycle– Execute – Performs the requested action– Write-back (Store) – Writes (stores) the results to a register or tomemory
  18. 18. © 2006 Prentice-Hall, Inc Slide 18Computers Are Your Future Chapter 6The Arithmetic-Logic UnitThe arithmetic-logic unit (ALU) performs basicarithmetic and logic operationsAdds, subtracts, multiplies, and dividesCompares alphanumeric data
  19. 19. © 2006 Prentice-Hall, Inc Slide 19Computers Are Your Future Chapter 6Microprocessor PerformanceData bus width – The number of pathways withinthe CPU that transfer data; they are measured in bits(8, 16, 32, or 64)Word size – The maximum number of bits of datathat the CPU can process at one time (8 bits, 16 bits,32 bits, or 64 bits)System Clock – electronic circuit that generatespulses at a rapid rate and synchronizes the computersinternal activities
  20. 20. © 2006 Prentice-Hall, Inc Slide 20Computers Are Your Future Chapter 6Microprocessor PerformanceOperations per cycle (clock speed) – The number ofclock cycles per second measured in megahertz(MHz) or gigahertz (GHz)Superscalar operations – Carrying out more than oneinstruction per clock cyclePipelining operations – Feeding a new instruction intothe CPU at every step of the processing cycle
  21. 21. © 2006 Prentice-Hall, Inc Slide 21Computers Are Your Future Chapter 6Parallel ProcessingParallel processing involves using more than one CPU toimprove performanceComplex instruction set computer (CISC) – A chip thatincludes special-purpose circuits that carry out instructions athigh speedsReduced instruction set computer (RISC) – A chip with abare-bones instruction set that results in a faster processingspeed than CISC chips
  22. 22. © 2006 Prentice-Hall, Inc Slide 22Computers Are Your Future Chapter 6Intel AdvancedMicro Devices(AMD)Cyrix Motorola (Apple)Pentium IVPentium MMXPentium IIIPopular CPUs
  23. 23. © 2006 Prentice-Hall, Inc Slide 23Computers Are Your Future Chapter 6The Chipset A chipset is a collection of chips that provide theswitching circuitry needed to move data throughout thecomputer
  24. 24. © 2006 Prentice-Hall, Inc Slide 24Computers Are Your Future Chapter 6Input/Output Bus The input/output bus provides apathway so that themicroprocessor can communicatewith input/output devices An input/output bus containsexpansion slots which holdexpansion cardsPCI (Personal ComputerInterface) slots are receptacles inwhich expansion cards areinserted. They support Plug andPlay (PnP) devices.PCI slotsExpansionCard
  25. 25. © 2006 Prentice-Hall, Inc Slide 25Computers Are Your Future Chapter 6MemoryRandom AccessMemory (RAM) Memory is the term used to describe devices that enable thecomputer to retain information. Program instructions and dataare stored in memory chips for quick access by the CPU.Read-OnlyMemory (ROM)Flash Memory
  26. 26. © 2006 Prentice-Hall, Inc Slide 26Computers Are Your Future Chapter 6Virtual memory: Part of the hard disk is reserved as RAM When RAM modules become full, the CPU accesses thehard disk to store and retrieve data Virtual memory is slower than RAMFULLVirtual Memory
  27. 27. © 2006 Prentice-Hall, Inc Slide 27Computers Are Your Future Chapter 6Random Access Memory (RAM)RAM is a type of memory that stores information temporarilyso that it’s available to the CPURAM is volatile; the memory’s contents are erased when thepower is turned offEach byte of memory has a unique location or memoryaddress
  28. 28. © 2006 Prentice-Hall, Inc Slide 28Computers Are Your Future Chapter 6Types of RAMDynamic RAM (DRAM) – A memory chip that needs tobe refreshed periodically or it will lose its dataSynchronous DRAM (SDRAM) is synchronized with thecomputer’s system clockRambus DRAM (RDRAM) uses a fast bus to send andreceive data within one clock cycle. It is faster thanSDRAMDouble data rate SDRAM (DDR SDRAM) is a type ofSDRAM that can send and receive data within one clockcycle
  29. 29. © 2006 Prentice-Hall, Inc Slide 29Computers Are Your Future Chapter 6KEYBOARDCPURAMMONITORCLICK ONCE TOBEGIN ANIMATIONProcessing a WordWEBWWEWEEBBB
  30. 30. © 2006 Prentice-Hall, Inc Slide 30Computers Are Your Future Chapter 6Cache MemoryPrimary cache (Level 1 or L1) – Located within the CPUchip, it is the memory that the microprocessor uses to storefrequently used instructions and dataSecondary cache (Level 2 or L2; Backside Cache) – Locatednear the CPU, it is the memory between the CPU and RAMCache memory is faster than RAM
  31. 31. © 2006 Prentice-Hall, Inc Slide 31Computers Are Your Future Chapter 6Drive baysOn/off switchReset buttonIndicator lightsFRONTBACKOutside the System UnitThe front panel contains drive bays, various buttons,and indicator lightsConnectors and ports are physical receptacles locatedon the back to connect peripheral devices to thecomputer
  32. 32. © 2006 Prentice-Hall, Inc Slide 32Computers Are Your Future Chapter 6Types of ConnectorsPS/2 port (mouse port) – Special serial port to connect mouse.PS/2 port (keyboard port) – Special serial port to connect keyboard.Universal Serial Bus (USB) – Allows up to 127 devices to beconnected at a time.Serial port – Data flows in a series of pulses, one after another one bitat a time; slow data transfer rate.Parallel port – Data flows through eight wires allowing the transfer ofeight bits of data simultaneously; faster than serial ports.VGA connector – A 15 pin connector used for monitorsGame port – A connector for high speed access for graphics-intensiveinteraction.Sound card connectors – Also called jacks, sound card connectorsaccept stereo mini-plugs. Microphone, line-in, line-out, and speakerconnectors are plugged into the card.Point and click on a connector below to view information about it.Click again to remove the text.
  33. 33. © 2006 Prentice-Hall, Inc Slide 33Computers Are Your Future Chapter 6 Small computer system interface (SCSI) port – Aparallel interface that enables up to eight devices tobe connected to it1394 (FireWire) port – A high-speed connection forup to 63 devices Infrared Data Association (IrDa) port – Infraredsignals are used to communicate between peripheraldevices and the system unitOther Types of Connectors
  34. 34. © 2006 Prentice-Hall, Inc Slide 34Computers Are Your Future Chapter 6 Telephone – modem interfaceNetwork – larger than telephone jackPC card slot – notebook computers have slot for PCcardsSound card connectors –Mic – microphone inputLine In – input from audio devicesLine Out – output to another audio deviceSpeaker – output to external speakersTV/sound capture – turns computer into a TV tunerAdditional Ports and Connectors
  35. 35. © 2006 Prentice-Hall, Inc Slide 35Computers Are Your Future Chapter 6Chapter 6 Summary• The basic unit of information is the bit• Large units of data are called kilobytes (KB), megabytes (MB),gigabytes (GB), and terabytes (TB)• The system unit contains the motherboard, which is a circuitboard that provides receptacles for chips and input/output buses• The central processing unit (CPU) contains the control unit (CU)and the arithmetic-logic unit (ALU). It manages the four basicoperations (fetch, decode, execute, and write-back).• The CPU processes data in a four-step cycle called a machinecycle. The CU manages four basic operations: fetch, decode,execute, and store.
  36. 36. © 2006 Prentice-Hall, Inc Slide 36Computers Are Your Future Chapter 6Chapter 6 Summary continued• The CPU’s performance is measured by the data bus width,operations per second, speed, and cache memory• Random access memory (RAM) is the computer’s main memory.It is volatile.• There are various types of RAM, including dynamic RAM(DRAM), synchronous DRAM (SDRAM), Rambus DRAM(RDRAM), and double data rate (DDR) SDRAM• Computers have ports such as serial ports, parallel ports, SCSIports, USB ports, FireWire ports, and IrDA ports to connectinput/output devices

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