Chapter 4 The Components of the System Unit

1. Chapter 4The Components of the System Unit

2. Ch 4 System Unit InstructionDataInformation InstructionsDataInformation Ch 1 – Introduction Ch 2 – Internet & WWW Ch 3 – Application Software Ch 8 – System Software Ports Cards Buses Clock Power Drives Control Unit Arithmetic Logic Unit (ALU) Memory InputDevices Ch 5 OutputDevices Ch 6 Information Data StorageDevices Ch 7

3. What is thesystem unit? • Case that contains electronic components of the computer used to process data

4. What is themotherboard? • Main circuit board of the system unit • Also calledsystem board

5. Components inside the system unit? • Processor • Memory • Clock • Adapter(extension) cards • Sound card • Video card • Drive bays • Powersupply • Ports • Buses

6. Processor • The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer Contains a control unit and an arithmetic logic unit (ALU)

7. Control unitis the component of the processor that directs and coordinates most of the operations in the computer • Arithmetic logic unit(ALU) performs arithmetic, comparison, and other operations

8. For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle

9. Memory Processor Control Unit Step 1. FetchObtain program instruction from memory Step 4. StoreWrite result to memory Step 2. DecodeTranslate instruction into commands ALU Step 3. ExecuteCarry out command

12. System Clock • Generates regular electronic pulses, or ticks, that set operating pace of components of system unit

13. How speed of the processor is measured? Each tick is a clock cycle Pace of system clock is clock speed Clock speeds are in the gigahertz (GHz- billion ticks per sec) Processor speed is also measured in millions of instructions per second (MIPS)

14. Clock speed (GHz) • Instructions per sec (MIPS) • Instructions per 1 watt energy (in millions) • (MIPW)

15. CPU begins executing the second instruction before completing the first instruction What is pipelining? Machine Cycle (without pipelining) Machine Cycle (with pipelining) Instruction 1 Instruction2 Instruction 3 Instruction 4

16. Doing Laundry A B C D • Ann, Brian, Cathy, Dave each have one • load of clothes to wash, dry, fold, slash • Washer takes 30 minutes • Dryer takes 30 minutes • Folder takes 30 minutes • Stasher takes 30 minutes

17. Sequential Laundry 2 AM 12 6 PM 1 8 7 11 10 9 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 T a s k O r d e r Time A B C D • Sequential laundry takes 8 hours for 4 loads

18. Pipelined Laundry 2 AM 12 6 PM 1 8 7 11 10 9 Time 30 30 30 30 30 30 30 T a s k O r d e r A B C D • Pipelined laundry takes 3.5 hours for 4 loads

19. Processor 1 Processor 2 Processor 3 Processor 4 Memory Memory Memory Memory • What isparallel processing? • Using multiple processors simultaneously to execute a program faster • Requires special software to divide problem and bring results together Control Processor Results combined

20. One processor on a chip More then one processor on a chip

21. Data of various nature are presented inside a computer in a digital form. We will see how.

23. What is a bit?

24. Eight bits grouped together as a unit are called a byte. Each byte has a unique address. Each of eight bits in a byte has a position

25. What a byte contains vs. what an output device will convey? • Contains: A sequence of 8 binary digits • Means: • Number • Character • Instruction • Sound pitch • Color • … • Depending on device

26. Representing numbers • Numbers have the most natural presentation. Each bit of a byte has a value depending on the position of the bit in a byte. • For example byte 01010101 carries numeric value of 64+16+4+1 = 85

27. Coding systems to represent text data • ASCII—AmericanStandardCodeforInformationInterchange • Unicode—coding scheme capable of representing allworld’s languages

29. Memory

30. 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 • What has to be stored?

32. Memory consists of locations (bytes). Each location in memory has an address • The number of locations in memory is memory size. • It is measured in kilobytes (KB or K), megabytes (MB), gigabytes (GB), orterabytes (TB)

33. The system unit contains two types of memory:

35. Adapter (Extension) Cards • Aflash memory cardallows users to transfer data from mobile devices to desktop computers • An PC card adds various capabilities to computers

36. Flash memorycan be electronically rewritten

37. Flash memory includes: • Memory cards, USB flash drives, and PC Cards modules

38. Memory cache speeds the processes of the computer because it is faster than memory and stores repeatedly used information

39. Access timeis the amount of time it takes the processor to read from memory. Measured in nanoseconds

40. Expansion slot • holds an • adapter card • Adapter card • enhances • functions and • provides • connections to • peripherals

41. With Plug and Play, the computer automatically configures adapter cards and peripherals as you install them

42. Ports and Connectors

43. Portconnects external devices to system unit

44. On a notebook computer, the ports are on the back, front, and/or sides

46. Single USB port can be used to attach multiple peripherals Third USB device connects to second USB, and so on PCs typically have several USB ports Second USB device connects to first USB First USB device connects to USB port • What areUSB ports? USB (universal serial bus) port can connect up to 127 different peripherals together with a single connector type USB 2.0

47. You can attach multiple peripherals using a single USB port with a USB hub

48. Other types of ports include:

49. What arespecial-purpose ports? • Allow users to attach specialized peripherals or transmit data to wireless devices • MIDI (Musical Instrument Digital Interface) port • IrDA (Infrared Data Association) port • Bluetooth port