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Discovering Computers Chapter 4 The Components of the System Unit.

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Presentation on theme: "Discovering Computers Chapter 4 The Components of the System Unit."— Presentation transcript:

1 Discovering Computers Chapter 4 The Components of the System Unit

2 2 Ch 4 System Unit Arithmetic Logic Unit (ALU) (ALU) Input Devices Ch 5 Storage Devices Ch 7 Output Devices Ch 6 Memory Data Information Instructions Data Information Instruction Data Information Control Unit Ch 1 – Introduction Ch 2 – Internet & WWW Ch 3 – Application Software Ch 8 – System Software Ports Cards Buses Clock Power Drives

3 What is the system unit?  Case that contains electronic components of the computer used to process data 3

4 What is the motherboard?  Main circuit board of the system unit  Also called system board 4

5 Components inside the system unit?  Memory  Clock  Adapter (extension) cards  Sound card  Video card  Drive bays  Power supply  Ports  Buses  Processor 5

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) 6

7 Control unit is 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 7

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

9 Processor Control Unit Memory Step 1. Fetch Obtain program instruction from memory Step 2. Decode Translate instruction into commands Step 4. Store Write result to memory Step 3. Execute Carry out command 9 ALU

10 The processor contains registers, that hold data and instructions The processor contains circuits that perform instructions using data 10

11 The system clock controls the timing of all computer operations 11

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

13 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) How speed of the processor is measured? 13

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

15 15 What is pipelining? Machine Cycle (without pipelining) Machine Cycle (with pipelining) Instruction 1 Instruction 2 Instruction 3 Instruction 4  CPU begins executing the second instruction before completing the first instruction

16 16 Doing Laundry Ann, Brian, Cathy, Dave each have one load of clothes to wash, dry, fold, slash ABCD °Dryer takes 30 minutes °Folder takes 30 minutes °Stasher takes 30 minutes °Washer takes 30 minutes

17 17 Sequential Laundry Sequential laundry takes 8 hours for 4 loads TaskOrderTaskOrder B C D A 30 Time 30 6 PM AM

18 18 Pipelined Laundry Pipelined laundry takes 3.5 hours for 4 loads TaskOrderTaskOrder B C D A 12 2 AM 6 PM Time 30

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

20 20 Single-core processor Multi-core processor 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. 21

22 Analog signals are continuous and vary in strength and quality Digital signals are in one of two states: on or off 22

23 What is a bit? 23

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 24

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 25

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 carries numeric value of = 85 26

27 Coding systems to represent text data  ASCII —American Standard Code for Information Interchange  Unicode —coding scheme capable of representing all world’s languages 27

28 28

29 Memory 29

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? 30 The operating system and other system software Application programs Data being processed and the resulting information

31 31

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), or terabytes (TB) 32

33 The system unit contains two types of memory: 33 Volatile memory Loses its contents when power is turned off Example: RAM Nonvolatile memory Does not lose contents when power is removed Examples: ROM, flash memory

34 Read-only memory (ROM) refers to memory chips storing permanent data and instructions 34

35 Adapter (Extension) Cards  A flash memory card allows users to transfer data from mobile devices to desktop computers  An PC card adds various capabilities to computers 35

36 Flash memory can be electronically rewritten 36

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

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

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

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

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

42 Ports and Connectors A port is the point at which a peripheral attaches to or communicates with a system unit (sometimes referred to as a jack) A connector joins a cable to a port 42

43  Port connects external devices to system unit 43

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

45 45

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

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

48 Other types of ports include: 48 Firewire port Bluetooth port SCSI port eSATA port IrDA port Serial port MIDI port

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

50 50

51 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 51

52 What is a serial port?  Transmits one bit of data at a time  Connects slow-speed devices, such as mouse, keyboard, modem 52

53 What is a parallel port?  Connects devices that can transfer more than one bit at a time, such as a printer 53

54 Buses What is a bus?  Channel that allows devices inside computer to communicate with each other  Bus width determines number of bits transmitted at one time 54

55 Bays What is a bay?  Opening inside system unit used to install additional equipment  Drive bays typically hold disk drives 55

56 Power Supply and cooling Converts AC Power into DC Power Fan keeps system unit components cool 56

57 To see the online addition to the book click here


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