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Chapter 4 The Components of the System Unit

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  1. Chapter 4The Components of the System Unit

  2. The System Unit Next • Case that contains electronic components of the computer used to process data system unit system unit handheld tablet system unit system unit system unit Smart phone system unit system unit Playstation iPOD system unit tablet What is thesystem unit? p. 184

  3. The System Unit • The inside of the system unit on a desktop personal computer includes:

  4. The System Unit Next • Main circuit board in system unit • Contains expansion slots, processor chips, and memory slots • Sometimes called a system board memory What is themotherboard? p. 186

  5. Processor Processor Control Unit Arithmetic Logic Unit (ALU) InstructionsDataInformation InstructionsDataInformation Next • Interprets and carries out basic instructions that operate a computer Control Unit Arithmetic Logic Unit (ALU) • Control unit directs and coordinates operations in computer • Arithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations Memory InputDevices OutputDevices Data Information • Also called theprocessor StorageDevices What is thecentral processing unit (CPU)? p. 187 Fig. 4-4

  6. Processor Memory Processor ALU Control Unit Next • Four operations of the CPU comprise a machine cycle Step 1. FetchObtain program instruction or data item from memory Step 2. DecodeTranslate instruction into commands Step 4. StoreWrite result to memory Step 3. ExecuteCarry out command What is amachine cycle? p. 188 Fig. 4-5

  7. Processor Next • Temporary high-speed storage area that holds data and instructions Stores location from where instruction was fetched Control Unit Stores instruction while it is being decoded Stores data while ALU computes it Stores results of calculation ALU What is aregister? p. 189

  8. Processor Next • Controls timing of all computer operations • Generates regular electronic pulses, or ticks, that set operating pace of components of system unit Each tick is a clock cycle Pace of system clock is clock speed Most 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) What is thesystem clock?

  9. MOORE’S LAW 1965 Computers double their capacity and number of circuits every two years. http://www.youtube.com/watch?v=UhZlk5bws9M

  10. Processor Next • A dual-core processor is a single chip that contains twoseparate processors • A multi-core processor is a chip with more than 2separate processors • Each processor on a dual-core/multi-core chip generallyruns at a slower clock speed, but increase overall performance • A quad processor is a chip with 4 separate processors Energy Efficient Why? What are dual-core and multi-core processors? p. 190

  11. Dual Core Processors Lower levels of power consumption Less heat emitted Boost multitasking

  12. Processor • The leading manufacturers of personal computer processor chips are Intel and AMD

  13. Processor • Determine how you plan to use a new computer before selecting a processor

  14. Data Representation Next • Most computers aredigital • Recognize only two discrete states: on or off • Use a binary system to recognize two states • Use Number system with two unique digits: 0 and 1, called bits (short for binary digits) How do computers represent data?

  15. Data Representation Next • Eight bits grouped together as a unit • Provides enough different combinations of 0s and 1s to represent 256 individual characters • Numbers • Uppercase and lowercase letters • Punctuation marks • Other What is abyte? p. 195 Fig. 4-12

  16. Data Representation ASCII Symbol EBCDIC 00110000 0 11110000 00110001 1 11110001 00110010 2 11110010 00110011 3 11110011 Next • ASCII—AmericanStandardCodeforInformationInterchange • EBCDIC—ExtendedBinaryCoded DecimalInterchangeCode • Unicode—coding scheme capable of representing allworld’s languages What are three popular coding systems to represent data? p. 195 Fig. 4-13

  17. Memory • Each location in memory has an address • Memory size is measured in kilobytes (KB or K), megabytes (MB), gigabytes (GB), or terabytes (TB)

  18. Data Representation Step 1.The user presses the capital letter T (SHIFT+T key) on the keyboard. Step 2.An electronic signal for the capital letter T is sent to the system unit. T Step 4.After processing, the binary code for the capital letter T is converted to an image, and displayed on the output device. Next Step 3.The system unit converts the scan code for the capital letter T to its ASCII binary code (01010100) and stores it in memory for processing. How is a letter converted to binary form and back? p. 196

  19. Memory • Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data • Stores three basic categories of items:

  20. Memory RAM RAM Next 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 interface Operating system instructions Step 2.When you start a Web browser, the program’s instructions are loaded into RAM from the hard disk. The Web browser window is displayed on the screen. Web browser instructions Web browser window Step 3.When you start a paint program, the program’s instructions are loaded into RAM from the hard disk. The paint program, along with the Web Browser and certain operating system instructions are in RAM. The paint program window is displayed on the screen. Paint program instructions Paint program window Step 4.When you quit a program, such as the Web browser, its program instructions are removed from RAM. The Web browser is no longer displayed on the screen. Web browser program instructions are removed from RAM Web browser window is no longer displayed on desktop How do program instructions transfer in and out of RAM? p. 198 Fig. 4-17

  21. Memory Next Memory chips that can be read from and written to by processor Also called main memory Most RAM is volatile, it is lost when computer’s power is turned off The more RAM a computer has, the faster it responds What israndom access memory (RAM)?

  22. Memory • The system unit contains two types of memory:

  23. Memory Next dual inline memory module • Resides on small circuit board calledmemory module • Memory slotson motherboard hold memory modules memory slot memory chip Where does memory reside? p. 199

  24. Memory Next • Depends on the types of software you plan to use • For optimal performance, you need more than minimum requirements How much RAM does a computer require? p. 199

  25. Memory • The amount of RAM necessary in a computer often depends on the types of software you plan to use

  26. Memory --What iscache? Next • Helps speed computer processes by storing frequently used instructions and data • Also called memory cache • L1 cache built into processor • L2 cache slower but has larger capacity • L2 advanced transfer cache is faster, built directly on processor chip • L3 cache is separate from processor chip on motherboard (L3 is only on computers that use L2 advanced transfer cache) p. 201 Fig. 4-20

  27. Memory Next Memory chips that store permanent data and instructions Firmware—Manufactured with permanently written data, instructions, or information What isread-only memory (ROM)? p. 201 - 202

  28. A USB Flash Drive The chip on the left is the flash memory. The microcontroller is on the right.

  29. Memory Term Speed Millisecond One-thousandth of a second Microsecond One-millionth of a second Nanosecond One-billionth of a second Picosecond One-trillionth of a second Next What isaccess time? • Amount of time it takes processor to read data from memory • Measured in nanoseconds (ns), one billionth of a second • It takes 1/10 of a second to blink your eye; a computer can perform up to 10 million operations in same amount of time p. 203 Figs. 4-22-4-23

  30. Expansion Slots and Adapter Cards • An expansion slot is a socket on the motherboard that can hold an adapter card • An adapter card (formerly called an expansion card)enhances functions of a component of the system unit and/or provides connections to peripherals • Sound card and video card

  31. Expansion Slots and Adapter Cards Next What is anexpansion slot? • An opening, or socket, on the motherboard that can hold an adapter card • WithPlug and Play, the computer automatically configures cardsand other devices as you install them p. 204 - 205 Fig. 4-25

  32. Ports and Connectors

  33. Ports and Connectors

  34. Ports and Connectors

  35. Ports and Connectors Next • Transmits one bit of data at a time • Connects slow-speed devices, such as a mouse, keyboard, or modem What is aserial port? p. 207 Fig. 4-30

  36. Ports and Connectors Next • Connects devices that can transfer more than one bit at a time, such as a printer What is aparallel port? p. 207

  37. Ports and Connectors Single USB port can be used to attach multiple peripherals in a daisy chain Third USB device connects to second USB device, and so on PCs typically have six to eight USB ports on front or back of the system unit Second USB device connects to first USB device First USB device connects to USB port on computer Next • What areUSB ports? USB (universal serial bus) port can connect up to 127 different peripherals together with a single connector type USB 2.0 p. 208

  38. Ports and Connectors Click to view Web Link,click Chapter 4, Click Web Linkfrom left navigation, then click FireWire Ports below Chapter 4 Next • Connects multiple types of devices that require faster data transmission speeds • Allows you to connect up to 63 devices together What areFireWire ports? p. 209

  39. Ports and Connectors A Bluetooth wireless port adapter converts a USB port into a Bluetooth port A smart phone might communicate with a notebook computer using an IrDA port

  40. Buses Next control bus • Channel that allows devices inside computer to communicate with each other • System bus connects processor and RAM • Bus width determines number of bits transmitted at one time • Wider the bus, the faster the transfer of data to the CPU • 32-bit bus vs. 64 bit processor System or internal bus http://zone.ni.com/devzone/cda/tut/p/id/5709 External bus bus What is abus? p. 211

  41. Bays Next What is abay? • Opening inside system unit used to install additional equipment • Drive baystypically hold disk drives p. 212 Fig. 4-36

  42. Power Supply External peripherals might use an AC adapter, which is an external power supply ConvertsAC PowerintoDC Power for the computer Fan keepssystem unit components cool Next AC = 115 volts DC= 5-12 volts What is a power supply? p. 213

  43. Expansion Slots and Adapter Cards Click to view Web Link,click Chapter 4, Click Web Linkfrom left navigation, then click ExpressCard Modules below Chapter 4 Next • Aflash memory cardallows users to transfer data from mobile devices to desktop computers • USB Flash drive What areflash memory cards? p. 205 Fig. 4-26–4-27

  44. Expansion Slots and Adapter Cards Click to view Web Link,click Chapter 4, Click Web Linkfrom left navigation, then click ExpressCard Modules below Chapter 4 Next • A PC card enables wireless Internet access for notebook computers • AnExpressCard moduleadds memory, communications, multi-media and security capabilities to notebook computers What arePC cards and ExpressCard modules? p. 205 Fig. 4-26–4-27

  45. Advantages of Express Cards over PC Cards • 45% smaller (ExpressCard/34) or 22% smaller (ExpressCard/54) than PC Card • Up to 2.5X faster than CardBus PC Cards • Lower cost due to elimination of CardBus controller in host and ability to easily repackage existing USB 2.0 and PCI Express peripheral designs into the ExpressCard form factor • Longer battery life due to move to lower voltages and superior power management

  46. Mobile Computers and Devices Next What is amobile computer? • Notebook, weighing between 2.5 and 9 pounds, or mobile device such as a PDA p. 213 - 214 Fig. 4-37

  47. Mobile Computers and Devices Next What ports are on a notebook computer? p. 214 Fig. 4-38

  48. Mobile Computers and Devices Next What ports and slots are on a tablet PC? p. 214 Fig. 4-39

  49. Summary