1. Chapter 2 Hardware Systems

2. 2 Hardware Systems Reading Sequence: 2.1 Processor and Memory 2.2 Peripherals 2.3 Storage Devices 2.4 Putting Together the Hardware Components 2.5 Improving Computer Performance Assessments: Exercise 2

3. 3 Figure 1 Component overview

4. 4 The chipset acts as the traffic cop ( 交警 ) controlling the flow of data and coordinating interactions among components in the system. Components pass data through the chipset, and the chipset monitors the data flow and passes data to other components.

5. 5 How these components work together. Example: the computer system completes a request to open a file and display the opened file on the monitor. 1.The microprocessor sends instructions to the storage devices (via the chipset) requesting the specified file to be loaded into main memory. 2.The storage devices send the file through the chipset to main memory. 3.The microprocessor fetches the file contents from main memory. 4.The microprocessor sends the display data to the monitor via the chipset.

6. 6 Figure 2 Data flow in a computer system

7. 7

8. 8 Figure 3 Components inside a computer

9. 9 A. Motherboard –Provides sockets for microprocessor and memory chips, slots for circuit boards, and the circuitry that enable electrical signals to travel from component to component. Most of the hardware components inside the system unit are attached to the motherboard. B. Power supply –Provides electrical power to the computer system. C. Microprocessor –Processes instructions stored in main memory. Sometimes, the microprocessor is found underneath a cooling fan to prevent it from overheating. Components inside a computer

10. 10 Components inside a computer D. Expansion slot –Serves as a socket on the motherboard into which an expansion card maybe inserted. E. Expansion card –Enables a computer to control peripheral devices such as the monitor and the microphone. F. Chipset –Controls data flow among components. G. IDE (Integrated Drive Electronics) cable –Transfers data from storage devices to the motherboard. H. Disk drives –Stores data permanently (even after the computer is turned off). They include the floppy disk drive, the CD-ROM (compact disk read-only-memory) drive, and the hard disk drive.

11. 11 Hardware Systems 2.1 Processor and Memory 2.1.1 Processor Basics The microprocessor is referred to as the Central Processing Unit (CPU). The job is to execute a series of machine instructions. Physically, the microprocessor is a single chip known as an integrated circuit (IC). Each chip is made out of silicon 硅 and it contains millions of transistors packed onto a chip. The Intel Pentium M Processor, introduced on March 12, 2003, has 77 million transistors, and the width of the smallest wire on the chip is 0.13 micron, or 0.00000013 meter. process the instructionsIntel Pentium M Processor

12. 12 TECHTALK: How a Microprocessor Executes Instructions There are two main components of the CPU: CU and ALU The control unit: accesses instructions stored in RAM, interprets what they mean, and then dispatches 分派, 派遣 them. The Arithmetic/Logic Unit (ALU): performs arithmetic, logic operations needed to process the instructions.

13. 13 TECHTALK: How a Microprocessor Executes Instructions A computer accomplishes a complex task by performing a series of very simple steps, referred to as instructions. An instruction tells the computer to perform a specific arithmetic, logical, or control operation. Two parts: the op code and the operands. The list of instructions that a CPU is able to execute is known as its instruction set.

14. 14 Instruction Execution with the CPU Four steps 1. Fetch - The control unit gets the instruction from memory. 2. Interpret - The control unit decodes what the instruction means and directs the necessary data to be moved from memory to the ALU. 3. Execute - The control unit directs the ALU to perform the necessary arithmetic or logic operations. 4. Store - The result of the computation is stored in memory.

15. 15 Figure 4 Fetch-Execute cycle

16. 16 A basic four-stage datapath Fetch Interpret Execute Store

17. 17  Another component of the microprocessor -- cache, a special high-speed memory that stores most recently used data in order to speed up the process of instruction execution. A cache can speed up data retrieval because recently used data is likely to be used again by the computer.

18. 18

19. 19 Level 1 (L1) cache memory or primary cache memory is located on the CPU to provide the CPU with the fastest access to data. Level 2 (L2) cache memory or secondary cache, located between the RAM and the CPU (sometimes on the CPU). Relative to the physical distance between the CPU and storage areas for data and instructions, data is retrieved more quickly from the L1 cache, then the L2 cache, and then the RAM.

20. 20 Performance: Factors and Measures  The rate at which instructions are processed is controlled by an internal clock, also known as the system clock. The internal clock sends pulses （脉冲） at a fixed rate to synchronize( 同步 ) all computer operations. The unit of measure for cycles （周期） per second is the hertz (Hz).  One Hz means one cycle per second, one kHz (kilohertz) means one thousand cycles per second, and one MHz means one million cycles per second. Computer clock cycles are closely related to the execution of instructions. So, a 3 GHz Pentium 4 machine can execute more instructions per second than a 2 GHz Pentium 4 machine. The greater the hertz, the faster the execution speed.

21. 21  IPS -- instructions per second  Today's computers sometimes execute multiple instructions in a single cycle. Thus, the number of instructions completed is independent of the number of cycles used. Sometimes machines are compared on the number of IPS.  Instructions can differ a great deal. Some complex instructions require a lot of cycles and take a comparatively long time to execute. Other instructions may be very simple and execute in very little time.

22. 22  bandwidth :Another measure of computer performance  the volume of data that can be transmitted within a fixed amount of time between components in a computer system (such as the transfer speed from the disk to the motherboard) or through connections to other computers. Bandwidth is expressed in bits per second (bps), or sometimes bytes per second (Bps) (recall that 8 bits equals 1 byte). Types of Processors  Intel,AMD,PowerPC(Macintosh family) …

23. 23 2.1.2 Types of Memory

24. 24 RAM  RAM (random access memory) is a temporary holding area for both data and instructions. It is also referred to as main memory  The data in RAM is lost when the computer is turned off.  RAM is measured by its memory capacity (the maximum number of bits or bytes that can be stored ) and latency (access time)  DRAM(Dynamic RAM),SRAM(Static RAM)

25. 25  Latency ( access time ) : the delay between the time when the memory device receives an address and the time when the first bit of data is available from the memory device. (ns)  通常的内存是指 RAM ，也称主存

26. 26 ROM  Read-only memory (ROM) is programmed with data hard-wired when it is manufactured. Data and instructions on a ROM are permanent, or nonvolatile （非易失性的）， which means they are not lost when power is turned off.  electrically erasable programmable read- only memory (EEPROM),--flash memory

27. 27 CMOS Memory  CMOS (complementary metal oxide semiconductor) memory stores configuration settings information of a computer  The CMOS chip requires very little electrical power to hold data  It can be powered by a small battery on the motherboard, or packaged with the chip  The battery maintains the data on the CMOS when the computer is turned off

28. 28 Figure 6 Memory decision tree

29. 29 Performance: Factors and Measures Lab 2-B Benchmarking Lab Assignments: Complete the 5 steps on Page 109 in Textbook Benchmarking– comparing disparate systems or components via a standardized set of instructions or series of tasks.

30. 30 Performance: Factors and Measures Benchmarking can test anything from just the processor to executing office applications. The comparison is measured by the time it takes to execute these instructions. It is important to assure that comparisons or claims are based on the same benchmarks. Benchmarking results by unbiased, independent organizations are especially useful.

31. 31 Hardware Systems 2.2 Peripherals (Section D Chapter 2 in textbook) 2.2.1 Connecting Peripherals –Expansion Slots and Cards –Ports –USB and FireWire –Comparing Different Ports 2.2.2 Buses 2.2.3 Input/Output Devices

32. 32 Figure 7 Peripheral devices and their connectors

33. 33 Expansion Slots and Cards

34. 34 Graphics card- video card, transforms images into analog data. A graphics card has its own memory and processor that handles computations necessary to convert image data to be displayed into pixels on the monitor.

35. 35 left is an Ethernet card used to plug into the PCMCIA slot of a laptop computer. right is an Ethernet card for a PCI slot in a desktop.

36. 36 Ports

37. 37 USB and FireWire  Universal Serial Bus (USB) : support for "hot connectivity" ; The data transfer rate for USB(1.1) is 1.5 MBps, USB-2 is developed with a data transfer rate of 60 MBps  Up to 127 devices can be connected to the system unit via a USB hub, which provides multiple USB ports  FireWire has a faster data transfer rate, the data transfer rate for FireWire is 50 MBps, FireWire 2 is developed with a data transfer rate of 100 MBps and it supports up to 63 devices.

38. 38 Comparing Different Ports PortUsageStatus FireWire Camcorder and external mass storage (e.g. CD-ROM, hard drive, etc.) Becoming the standard for digital video devices USBMost devices Becoming the standard for most peripheral devices ParallelPrinterBecoming obsolete SerialModemBecoming obsolete PS/2Keyboard, mouseBecoming obsolete Table 1 Comparison of ports

39. 39 2.2.2 Buses

40. 40 2.2.2 Buses A bus is a pathway through which data is transferred from one part of a computer to another. It consists of the data bus and the address bus. The data bus transfers the data itself, while the address bus transfers information about where the data is to go. Every bus has a width, a speed, and a transfer rate.

41. 41 The width, also called the word size, of a bus is measured in bits. An 8-bit bus has eight transfer pathways that are one bit wide, meaning eight bits of data may be transferred simultaneously （同时地） The speed of a bus is measured in hertz (Hz), or cycles per second. Transfer rate is the measure of how much data may be moved from one device to another in one second

42. 42 Data traveling through the bus can pass through expansion slots, cards, ports, and cables. For buses that may be X-pumped and/or Y-channeled, the peak transfer rate is the word size (in bytes) * speed * X * Y. One way to enhance data transfer rate is to transfer data multiple times during a cycle. X- pumped indicates that data can be transmitted X times in a cycle. Another way to increase the amount of data transferred is to increase the number of channels used to transfer data. Y- channeled indicates that Y data channels are used to transfer data. Also, the closer a component is to the chipset, the faster the data can be transferred to the chipset.

43. 43 The front side bus, is the bus on the motherboard that transfers data between the CPU and the chipset. In modern computers, there is a great mismatch between the speed of the system bus and the internal speed of the much-faster CPU. This means that one of the major obstacles( 障碍 ) to faster processing is system bus transfer rate. The IDE bus is the interface that transfers data between storage devices and the chipset.

44. 44 RDRAM bus and DRAM bus are examples of memory buses. Because the CPU fetches instructions and data from RAM, the smaller the difference between bus speeds of CPU and RAM, the more efficient the processing. There are two common types of expansion slots found on motherboards, Peripheral Component Interconnect (PCI) and Accelerated Graphics Port (AGP). An expansion slot that used to be common was the Industry Standard Architecture (ISA). ISA was the original bus standard for data transfers from expansion cards to the system bus. The word size or width of the data path on the ISA bus is 16 bits, running at a mere 8 MHz. It is now replaced by the speedier PCI, developed by Intel.

45. 45 2.2 Peripherals 2.2.3 Input/Output Devices Input Devices The most common input devices are the mouse and the keyboard. With increased available bandwidth and speed, and decreased cost, other types of input devices are becoming more widely used. Example: Digital Camera ; Scanners ; Digital Camcorders

46. 46 Output Devices CRT Monitors 、 LCD Monitors 、 Projectors are typical devices to view outputs on a screen. There are a number of types of printers that perform a variety of functions. Such as Ink Printers ; Dye-Sublimation Printers ; Laser Printers

47. 47 Cathode ray tube (CRT) monitors used to be the most common type of computer monitors until LCD monitors (discussed below) began to gain popularity. CRT monitors use three electron beams to create colors, red, green, and blue. To generate the color white, all three beams are fired simultaneously. To create the color black, all three beams are turned off. Other colors are created using different mixtures of these three color beams. They are inexpensive and dependable for displaying images on screen. Cathode ray tubes are also found in conventional TV sets.

48. 48 Hardware Systems 2.3 Storage Devices Why does a computer need to store files on a hard disk drive? Why not keep everything in RAM memory? RAM memory is volatile hard disk drives are useful is that they have a much larger capacity than RAM. A typical personal computer today will have at least 128 megabytes of RAM memory and 40 gigabytes of disk storage. So, even though hard disk drives are slow as compared to RAM, they are an important component of your computer system. Assessments: Multiple-Choice Quiz 6

49. 49 2.3.1 Disk Controller Interfaces There are many common interfaces to connect a storage device to a computer. Such as USB, FireWire, IDE, EIDE IDE Interface An IDE is the interface that enables data to transfer between storage devices and the chipset. IDE is designed specifically as disk interface whereas USB and FireWire can interface with other devices besides storage devices such as digital cameras and printers. An IDE interface provides a standard way for storage devices to connect to a computer. The controller for the IDE is usually integrated into the disk or CD-ROM drive, and the controller directs how the hard drive stores and accesses data.

50. 50

51. 51 EIDE Master/Slave EIDE is Enhanced IDE, a newer version of the IDE mass storage device interface standard. The EIDE interface provides a set of two IDE ports. One is referred to as the primary port, the other as the secondary. Each port attaches to a cable containing two plugs, and each plug can connect to a device primary master, primary slave, secondary master, and secondary slave To distinguish between devices on the same IDE port, one device is considered the master, the other the slave, resulting in the following designations: primary master, primary slave, secondary master, and secondary slave.

52. 52 Hardware Systems 2.3 Storage Devices 2.3.2 Mass Storage( 大容量存储器 )  How Mass Storage Devices Differ from RAM slow access times and low transfer rates located far from the processor nonvolatile ( 非易失性 ) huge capacities ( 海量 ) cost per bit stored is far lower than RAM ( 价廉 ) removable media

53. 53  Disk Drive Reliability mean time between failures (MTBF)  Optical Media: CDs versus DVDs  Magnetic Media ： range from some of the smallest capacity storage devices, floppy disks, to the largest capacity devices, hard disk drives

54. 54 NameTypeCapacityWritability High-density floppy diskMagnetic1.44 MBUnlimited SmartMedia cardSolid state2 - 256 MBMany CompactFlash cardSolid state4 MB - 4 GBMany Super floppyMagnetic120 or 240 MBUnlimited USB storage deviceSolid state64, 128, 256 MB, or moreMany CompactFlash form factor—MicrodriveMagnetic340 MB, 1 GB, 4 GBUnlimited Iomega Zip diskMagnetic100, 250, or 750 MBUnlimited CD-ROMOptical650 or 700 MBRead only CD-ROptical650 or 700 MBWrite once CD-RWOptical650 or 700 MBMany Iomega Jaz diskMagnetic1 or 2 GBUnlimited DVD-ROptical4.7 GBWrite once DVD-RWOptical4.7 GBMany DVD-ROM (SLSS)Optical4.7 GBRead only DVD-ROM (DLSS or SLDS)Optical9.4 GBRead only DVD-ROM (DLDS)Optical18.8 GBRead only Hard disk driveMagnetic20 GB and upUnlimited HDD Desktop external hard driveMagnetic20, 30, 40 GB, or moreUnlimited

55. 55 Hardware Systems 2.4 Putting Together the Hardware Components 2.4.1 How Components Work Together Learning Goal: Knowledge of how components introduced in this unit work with one another to enable a computer to function

56. 56 Overview of hardware components

57. 57 The CPU executes instructions stored in memory devices. When the computer is being booted, the CPU fetches instructions from the permanent memory devices, ROM and CMOS. ROM is read-only memory that stores instructions needed to start up the computer. CMOS contains system configuration data. Once the computer is booted, RAM is used to load the rest of the instructions to be executed by the CPU.

58. 58 Data from storage devices such as the CD-ROM drive and the hard drive are passed through the disk controller. Data can also be stored on hard disk or CD. Data in the hardware system passes through buses. The buses are the communication channels among components in the system unit. Peripheral devices such as the keyboard, mouse, printer, speakers, etc. are connected to the computer via ports typically in the back of a system unit. When a computer processes requests from the user, the CPU directs the other components to carry out specific tasks, and data is passed among components through buses and the chipset.

59. 59 Example: To save a file to hard disk, the CPU would pass the data to be saved through the front bus to the chipset. The chipset sends the file data via the PCI bus to the disk controller, which would then send the data to the hard disk storage device. To open and display an image file, the CPU would signal the disk controller to fetch the image file on the storage device and store it in RAM. The graphics card would then access the image data and display the image as pixels on the computer monitor. These are generalizations for how components interact. When trying to understand a hardware system, keep in mind the general concepts of how components work together, and investigate the specifications of components to gain more precise understanding of how a given hardware system works.

60. 60 2.4.2 Lab: Researching a Computer System 2.4.3 Lab: Online Configuration You can research a computer system using the Web by retrieving product reviews and price comparisons.

61. 61 2.5 Improving Computer Performance How do you measure computer performance? How is computer performance being improved? Reading Sequence: 2.5.1 Moore's Law. 2.5.2 Bottlenecks. Assessments: Multiple-Choice Quiz 7 Hardware Systems

62. 62 2.5.1 Moore's Law With the exponential growth of transistor density on microchips, many inferences can be made that allow analysts to predict other developments in the computer industry. Extending the scope of Moore's Law, the following predictions can be made: Processing power (speed) doubles every 12-18 months. Storage capacity of RAM doubles every 12-18 months. Moore's Law, an example of exponential growth, refers specifically to the capacity of microchips, and the law might be stated this way: the number of transistors that can be put on a microchip will double every 12-18 months, until physical limitations are reached.

63. 63 An interesting counter to improvements in capacity and throughput is known as Parkinson's Law of Data, which says that data expands to fill the space available. In other words, as more memory or disk space becomes available, the demand for more memory or disk space increases accordingly. For example, when computers had only a few kilobytes (KB) of memory, their simple OS fit in as little as 4 KB. Today's microcomputers typically have 128 MB or more of memory and, as Parkinson's Law would predict, today's OS are much more elaborate and require tens of megabytes of memory for their own use.

64. 64 2.5.2 Bottlenecks Bottlenecks—Slowing a Process Wide-mouthed glasses empty their contents more rapidly than bottles with long thin necks. To do any task, many steps are involved. A bottleneck is a step that takes a long time to complete, and thus reduces overall performance. Just as in the adage “A chain is only as strong as its weakest link,” it is true that a process‘s speed, or throughput( 吞吐量 ), is limited by its slowest step. If other parts of your computer are too slow, buying a faster processor may not speed things up at all!

65. 65 Typical Bottlenecks The following are some areas of the hardware system that may contain a bottleneck: Cache RAM I/O Video card (particularly for 3-D gaming)  The cache slows the system down when there is not enough cache. Faster processors requiring more data input to run optimally may not receive enough data from small caches.  RAM loads instructions from programs on disk. Therefore if there is not enough RAM memory, instructions will need to be loaded frequently from disk slowing down the execution of program instructions.

66. 66  I/O covers information transfer. Are the buses fast enough? Is the hard drive fast enough? The components may be able to send the data quickly enough, but if the system cannot transfer the data just as quickly, the system slows down.  Most business users will not suffer from a slow video card. Gamers, graphics designers, and some engineers need high-speed video cards in order to keep pace with the requirements of the software. The average user does not need one of these video cards; however, the slow 3-D rendering frame-rates produced by slower cards may hamper （妨碍） the performance of some applications.

67. 67 Eliminating Bottlenecks –Can we speed up a computer? Actually it isn't usually the computer that you want to speed up, but the tasks it performs. This is an important distinction. Speeding up the computer suggests buying a faster processor, installing faster memory, getting a faster bus, or installing faster disk drives and video controllers.

68. 68 –The key to making effective improvements is to understand why certain tasks take so long. Often, you can do some simple experiments to see whether or not a certain item is the bottleneck. This idea is applied in a very straightforward way by software developers, who use profiling tools to measure how long various sections of their programs take. That way they can identify the bottlenecks and most time-consuming steps, and focus their attention on improving those portions of the code.

69. 69 Exercise 2 Please answer the following question(s). If the assessment includes multiple-choice questions, click the "Submit Answers" button when you have completed those questions. Prerequisite: Exercise 1 Direction: Use a word processor (Microsoft Word) to answer the questions in the exercise.

70. 70 Exercise 2 Question 1. Choosing Microprocessors The following processors are made by Intel: A. Mobile Intel® Pentium® 4 Processor with Hyper-Threading Technology Processor speed: 3.2GHz Low power consumption Level 2 cache: 512KB System bus: 800 MHz Hyper-Threading Technology B. Mobile Intel Pentium® 4 Processor-M Processor speed: 2.8GHz Level 2 512KB System bus: 533 MHz

71. 71 Exercise 2 C. Intel Celeron® Processor speed: 2.8 GHz Level 2 128KB System bus: up to 400 MHz You may find the following resources useful: Intel Notebook Processors The CPU Scorecard

72. 72 Exercise 2 a. List the processors described above by their price range (from the cheapest to the most expensive). b. List the processors described above by their performance (from the best to the worst). c. Which of the above processors would be the fastest when used for multi-media production and multi-tasking (running 10 or more applications at the same time)?

73. 73 Exercise 2 Question 2. Computer Purchase Let us assume that you are purchasing a new computer for a specific usage. You need to choose a computer from various available configurations. Listed below are four different usage cases of a computer (a-d). For each usage case, identify components of the computer configuration that are most important to consider. Explain your answers.

74. 74 Components to be considered include (but are not limited to): Monitor size/resolution Graphics card/video card Storage devices (for example, DVD-ROM) Memory (RAM, cache, and hard disk) Disk controller interfaces (ATA, EIDE) For example, if a computer were to be used for viewing movies, a DVD-ROM drive is needed since movies are available as CDs and now increasingly as DVDs. A large monitor (about 19”) that supports high resolutions and a video card will also be necessary to enjoy the movie.

75. 75 a. Simultaneously running a number of programs b. Running a speed-critical application c. Storing and retrieving huge volumes of data d. Purchasing a basic configuration, to be upgraded later as needed

76. 76 Question 3. Laptop Computer Selection You are a new graduate student enrolling in a Masters in Information Technology program. The department requires you to have a computer with the following requirements: 512 MB of RAM 20 GB hard drive CD-ROM drive Wireless connection Ethernet network card Windows XP Professional version

77. 77 Your school has wireless connection, and Ethernet jacks. However, some classes are three hours long, and your AC adapter may not be long enough to reach an outlet. You also would be carrying this computer around from class to class. The most you can spend is US$1200. Indicate the range of values you desire for each of the following criteria: a. Weight b. Screen size c. Number of USB ports d. Number of Firewire ports e. Need CD-RW? f. Need DVD-ROM? g. Need DVD-RW? h. Manufacturer preferences?

78. 78 i. Search the Internet for two suitable computers meeting the above requirements and your budget constraint. Submit screenshots of the Web pages detailing the computer configuration and price. j. Record your search results in a MS Excel spreadsheet. Fill column A with the following category labels: 1. Manufacturer 2. Processor 3. Memory (maximum upgrade capacity) 4. Screen size 5. Weight 6. Graphics card 7. USB

79. 79 8. Firewire 9. CD-ROM 10. DVD-ROM 11. Communications (e.g. wireless, Ethernet) 12. Battery life 13. Price 14. Available Rebate Save and submit your Excel file. k. Make your final purchase decision and justify your decision.

80. 80 Question 4. File Compression In this section, you will use a compression algorithm to compress a message. Then you will use a compression application to determine the properties of compression. a. How does dictionary-based compression work? Use dictionary-based compression to compress the message below: sea shells, sea horses, and seals are in the sea.

81. 81 b. How many bytes does the message above contain (each character is 1 byte including spaces)? c. Create a compression dictionary and calculate its size in bytes. d. What is the compressed the message? e. How many bytes did the entire compression use? f. Is dictionary-based compression a lossy compression? Explain.

82. 82 Copy and paste the entire content of this exercise into Notepad and save it as compress0.txt Compress this file using WinZip or any compression application and name it compress1.zip. If you do not have WinZip application installed on your computer, refer to Appendix B. Downloading WinZip Appendix for directions to download the application. g. What is the size of the file before and after compression? What is the compression ratio of compress1.zip to the original file? Compress compress1.zip and name it compress2.zip.

83. 83 h. What is the compression ratio of compress2.zip to compress1.zip? Explain what is happening. (Hint: think of information that needs to be stored for a compression.) i. Is this a lossy or lossless compression? What do you think would happen if you kept on compressing the file successively? j. Is lossy compression appropriate for compressing images? Is it appropriate for hard disk backups? Provide explanations for both parts.