bit, Byte, Kilobyte
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- 1. Computers AreYour Future 2006 Prentice-Hall, Inc.
2. 2006 Prentice-Hall, Inc Slide 2Computers Are Your Future Chapter 6Computers Are Your FutureChapter 6Inside the System Unit 3. 2006 Prentice-Hall, Inc Slide 3Computers Are Your Future Chapter 6What You Will Learn . . .Understand how computers represent dataUnderstand the measurements used to describe datatransfer rates and data storage capacityList the components inside the system unitList the components on the motherboardHow a CPU processes data 4. 2006 Prentice-Hall, Inc Slide 4Computers Are Your Future Chapter 6What You Will Learn . . .Factors that determine a microprocessorsperformanceThe types and purpose of memory in a computersystemThe physical connectors on the exterior of the systemunit 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. 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. 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. 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 storageExample: 20 GB hard drive 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. 2006 Prentice-Hall, Inc Slide 10Computers Are Your Future Chapter 6ASCII and EBCDIC Code 11. 2006 Prentice-Hall, Inc Slide 11Computers Are Your Future Chapter 6The System UnitThe system unit is a boxlike case that houses the computersmain 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. 2006 Prentice-Hall, Inc Slide 12Computers Are Your Future Chapter 6DesktopNotebookPersonal DigitalAssistantTypes of System Units 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 thecomputers hard drive, floppy drive,and CD-ROM / DVD-ROM drives 14. 2006 Prentice-Hall, Inc Slide 14Computers Are Your Future Chapter 6The Motherboard The motherboard provides thecentralized connection pointfor the computers componentsMost components areintegrated circuits (chips) Chips carry electrical currentand contain electronicswitches or transistors 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 computers components 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. 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 cycleThe processing cycle consists of two phases: Instruction Cycle Fetch Gets the next program instruction from the computersmemory 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. 2006 Prentice-Hall, Inc Slide 18Computers Are Your Future Chapter 6The Arithmetic-Logic UnitThe arithmetic-logic unit (ALU) performs basicarithmetic and logic operationsAdds, subtracts, multiplies, and dividesCompares alphanumeric data 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. 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 cyclePipelining operations Feeding a new instruction intothe CPU at every step of the processing cycle 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. 2006 Prentice-Hall, Inc Slide 22Computers Are Your Future Chapter 6Intel AdvancedMicro Devices(AMD)Cyrix Motorola (Apple)Pentium IVPentium MMXPentium IIIPopular CPUs 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. 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 cardsPCI (Personal ComputerInterface) slots are receptacles inwhich expansion cards areinserted. They support Plug andPlay (PnP) devices.PCI slotsExpansionCard 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. 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. 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 its available to the CPURAM is volatile; the memorys contents are erased when thepower is turned offEach byte of memory has a unique location or memoryaddress 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 dataSynchronous DRAM (SDRAM) is synchronized with thecomputers system clockRambus DRAM (RDRAM) uses a fast bus to send andreceive data within one clock cycle. It is faster thanSDRAMDouble data rate SDRAM (DDR SDRAM) is a type ofSDRAM that can send and receive data within one clockcycle 29. 2006 Prentice-Hall, Inc Slide 29Computers Are Your Future Chapter 6KEYBOARDCPURAMMONITORCLICK ONCE TOBEGIN ANIMATIONProcessing a WordWEBWWEWEEBBB 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. 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. 2006 Prentice-Hall, Inc Slide 32Computers