K.Ng Sept08

1

Inside the Computer

ITMA Lecture 02

1

Inside the Computer

Krates Ng

What You Will Learn . . .

Understand how computers represent dataUnderstand the measurements used to describe data transfer rates and data storage capacityList the components inside the system unit

2

List the components inside the system unit List the components on the motherboard How a CPU processes data

What You Will Learn . . .

Factors that determine a microprocessors performanceThe types and purpose of memory in a computer system

3

yThe physical connectors on the exterior of the system unit

A Bit of Computer History

• ENIAC in 1946

5,000 operations per sec.

1 000 sq feet

4

1,000 sq. feet

I/O: cards, lights, switches

(cont’)

• First commercial computer: UNIVAC I in 1951

1,905 operations/sec.

943 cubic feet

5

I/O: magnetic tapes, printer

Cost: US$750,000

Vacuum Tube or Valve

6

K.Ng Sept08

2

(cont’)• IBM Personal Computer XT in 1981

7

The Birth of Apple

• Apple I in 1976

CPU: 6502 at 1MHz

RAM: 4KB Standard, expandable to 8KB or 48KB

Graphics: 40x20 characters

8from www.apple-history.com

p

Cost: US$666.66

Apple ][

Introduced in 1977

CPU: 6502 at 1MHz, 8-bit

RAM: start from 4KB

9

ROM: 12KB

Cost: US$1,298.00

Macintosh – the Birth of GUI

Introduced in 1984

CPU: Motorola MC68000 at 8MHz, 16 bits

ROM: 64KB RAM: 128KB max.

10

3.5” 400KB floppy drive

Weight: 16 lbs.

Cost: US$2,495.00

Apple Macintosh commercial aired during 1984 Superbowl

Miniaturization

11

TransistorsIntegrated Circuits

For More….

History on computers and technologywww.computerhistory.org

History on the Apple computers

12

y pp pwww.apple-history.comwww.theapplemuseum.com

K.Ng Sept08

3

Describing Hardware Performance

Hardware performance refers to the amount of data a computer can store and how fast it can process the data

Socket 478 ATX Intel Pentium 480 GB

7200 RPM

System Case

13

ATX Motherboard 2.4Ghz Processor7200 RPM

Hard Drive

512 MB DDR SDRAM

Memory Module

OFF

ON

0 1OR = 1 bit

10 0 001 1OR= 1 Byte

= 1 Byte

OFF

0

How Computers Represent DataON

14

0 0 0 0 01 10

Bit (Binary digit) – On or off state of electric current; considered the basic unit of information; represented by 1s and 0s (binary numbers)

Byte – Eight bits grouped together to represent a character (an alphabetical letter, a number, or a punctuation symbol); 256 different combinations

1000 bits = 1 kilobit (kb)

1,000,000 bits = 1 megabit (mb)

1,000,000,000 bits = 1 gigabit (gb)

Bits

15

Kilobits per second (Kbps), megabits per second (Mbps), and gigabits per second (Gbps) are terms that describe units of data used in measuring data transfer rates

Example: 56 Kbps modem

8 bits = 1 Byte

1024 Bytes = 1 Kilobyte (KB)

1,048,576 Bytes = 1 Megabyte (MB)

1,073,741,824 Bytes = 1 Gigabyte (GB)

1 099 511 627 776 Bytes = 1 Terabyte (TB)

Bytes

16

1,099,511,627,776 Bytes = 1 Terabyte (TB)

Kilobyte, megabyte, gigabyte, and terabyte are terms that describe large units of data used in measuring data storage

Example: 20 GB hard drive

Example

Convert 13,467,823 bytes into MB

1. 13,467,823/1024 = 13152.2 KB

17

2. 13,152.2 KB/1024 = 12.84 MB

Representing Characters: Character CodesCharacter codes translate numerical data into characters readable by humans

American Standard Code for Information Interchange (ASCII) – Eight bits equals one character; used by minicomputers and personal computersExtended Binary Coded Decimal Interchange Code (EBCDIC) – Eight bits equals one character; used by mainframe

18

0 10 0 001 1= 4

= 4

( ) g q ; ycomputersUnicode – Sixteen bits equals one character; over 65,000 combinations; used for foreign language symbols

ASCII

0 001 11 1 1EBCDIC

K.Ng Sept08

4

ASCII and EBCDIC Code

19

The System Unit

20

The system unit is a boxlike case that houses the computer’s main hardware components

A footprint is the space taken up on the desk by the computer

Form factor refers to the way the internal components are mounted in the unit

Desktop Notebook

Types of System Units

21

Personal Digital Assistant

Inside the System UnitMotherboard (mainboard) – Large printed circuit board with thousands of electrical circuitsPower supply – Transforms alternating current (AC) from wall outlets to direct current (DC) needed by the computer

22

Cooling fan – Keeps the system unit coolInternal Speaker – Used for beeps when errors are encounteredDrive bays – Housing for the computer’s hard drive, floppy drive, and CD-ROM / DVD-ROM drives

The MotherboardThe motherboard provides the centralized connection point for the computer’s components

Most components are integrated circuits (chips)

23

Chips carry electrical current and contain electronic switches or transistors

The Central Processing Unit: The Microprocessor

24

CPU

CPU socket

Central processing unit (CPU) – A microprocessor that interprets and carries out instructions given by software. It controls the computer’s components

K.Ng Sept08

5

Components of the CPU

Control unit – Coordinates and controls all parts of the computer system

Arithmetic-logic unit – Performs arithmetic or logical operations

25

Registers – Temporarily store the most frequently used instructions and data

Intel P4 (1)

26

Intel P4 (2)

27

Moore’s LawIn 1965, Gordon Moore said “The complexity for min. component costs hasincreased at a rate of roughly a factor of two per year…”

28www.intel.com/technology/mooreslaw/index.htm

The Control UnitThe control unit manages four basic operations (fetch, decode, execute, and write-back)

The four-step process is known as the machine cycle or processing cycleThe processing cycle consists of two phases:

Instruction CycleFetch Gets the next program instruction from the computer’s

29

– Fetch – Gets the next program instruction from the computer smemory

– Decode – Figures out what the program is telling the computer to do

Execution Cycle– Execute – Performs the requested action– Write-back (Store) – Writes (stores) the results to a register or to

memory

The Arithmetic-Logic Unit

The arithmetic-logic unit (ALU) performs basic arithmetic and logic operations

Adds, subtracts, multiplies, and divides

30

Compares alphanumeric data

K.Ng Sept08

6

Microprocessor PerformanceData bus width – The number of pathways within the CPU that transfer data; they are measured in bits (8, 16, 32, or 64)

Word size – The maximum number of bits of data that the CPU can process at one time (8 bits 16 bits

31

that the CPU can process at one time (8 bits, 16 bits,32 bits, or 64 bits)

System Clock – electronic circuit that generates pulses at a rapid rate and synchronizes the computers internal activities

Microprocessor PerformanceOperations per cycle (clock speed) – The number of clock cycles per second measured in megahertz (MHz) or gigahertz (GHz)

Superscalar operations – Carrying out more than one instruction per clock cycle

32

instruction per clock cycle

Pipelining operations – Feeding a new instruction into the CPU at every step of the processing cycle

Parallel Processing

Parallel processing involves using more than one CPU to improve performanceComplex instruction set computer (CISC) – A chip that includes special-purpose circuits that carry out instructions at high speeds

33

Reduced instruction set computer (RISC) – A chip with a bare-bones instruction set that results in a faster processing speed than CISC chips

Intel Advanced Micro Devices (AMD)Pentium IVPentium MMX

Pentium III

Popular CPUs

34

Cyrix Motorola (Apple)

Pentium III

The Chipset

35

A chipset is a collection of chips that provide the switching circuitry needed to move data throughout the computer

Input/Output Bus

The input/output bus provides a pathway so that the microprocessor can communicate with input/output devicesAn input/output bus contains expansion slots which hold

PCI slots

36

expansion slots which holdexpansion cards

PCI (Personal Computer Interface) slots are receptacles in which expansion cards are inserted. They support Plug and Play (PnP) devices. Expansion

Card

K.Ng Sept08

7

Memory

Random Access

Read-Only Memory (ROM)

37

Random Access Memory (RAM)

Memory is the term used to describe devices that enable the computer to retain information. Program instructions and data are stored in memory chips for quick access by the CPU.

Flash Memory

FULL

Virtual Memory

38

Virtual memory:

Part of the hard disk is reserved as RAM

When RAM modules become full, the CPU accesses the hard disk to store and retrieve data

Virtual memory is slower than RAM

Random Access Memory (RAM)

39

RAM is a type of memory that stores information temporarily so that it’s available to the CPU

RAM is volatile; the memory’s contents are erased when the power is turned off

Each byte of memory has a unique location or memory address

Types of RAM

Dynamic RAM (DRAM) – A memory chip that needs to be refreshed periodically or it will lose its data

Synchronous DRAM (SDRAM) is synchronized with the computer’s system clock

40

Rambus DRAM (RDRAM) uses a fast bus to send and receive data within one clock cycle. It is faster than SDRAM

Double data rate SDRAM (DDR SDRAM) is a type of SDRAM that can send and receive data within one clock cycle

KEYBOARD RAM

MONITORCLICK ONCE TO BEGIN ANIMATION

Processing a Word

B

W

EW

E

B

B

B

41

CPU

W

E

B

W

EWE

BB

Cache Memory

P i h (L l 1 L1) L d i hi h CPU

42

Primary cache (Level 1 or L1) – Located within the CPUchip, it is the memory that the microprocessor uses to store frequently used instructions and data

Secondary cache (Level 2 or L2; Backside Cache) – Located near the CPU, it is the memory between the CPU and RAM

Cache memory is faster than RAM

K.Ng Sept08

8

Drive bays

On/off switch

Reset button

Indicator lightsBACK

Outside the System Unit

43

Indicator lights

FRONT

The front panel contains drive bays, various buttons, and indicator lightsConnectors and ports are physical receptacles located on the back to connect peripheral devices to the computer

Types of ConnectorsPoint and click on a connector below to view information about it. Click again to remove the text.

44

PS/2 port (mouse port) – Special serial port to connect mouse.PS/2 port (keyboard port) – Special serial port to connect keyboard.Universal Serial Bus (USB) – Allows up to 127 devices to be connected at a time.Serial port – Data flows in a series of pulses, one after another one bit at a time; slow data transfer rate.Parallel port – Data flows through eight wires allowing the transfer of eight bits of data simultaneously; faster than serial ports.VGA connector – A 15 pin connector used for monitorsGame port – A connector for high speed access for graphics-intensive interaction.Sound card connectors – Also called jacks, sound card connectors accept stereo mini-plugs. Microphone, line-in, line-out, and speaker connectors are plugged into the card.

Small computer system interface (SCSI) port – A parallel interface that enables up to eight devices to be connected to it1394 (FireWire) port – A high-speed connection for up to 63 devices

Other Types of Connectors

45

pInfrared Data Association (IrDa) port – Infrared

signals are used to communicate between peripheral devices and the system unit

Telephone – modem interfaceNetwork – larger than telephone jackPC card slot – notebook computers have slot for PC cardsSound card connectors –

Additional Ports and Connectors

46

Mic – microphone inputLine In – input from audio devicesLine Out – output to another audio deviceSpeaker – output to external speakers

TV/sound capture – turns computer into a TV tuner

Summary

• The basic unit of information is the bit• Large units of data are called kilobytes (KB), megabytes (MB),

gigabytes (GB), and terabytes (TB)• The system unit contains the motherboard, which is a circuit

board that provides receptacles for chips and input/output buses • The central processing unit (CPU) contains the control unit (CU)

47

• The central processing unit (CPU) contains the control unit (CU)and the arithmetic-logic unit (ALU). It manages the four basic operations (fetch, decode, execute, and write-back).

• The CPU processes data in a four-step cycle called a machine cycle. The CU manages four basic operations: fetch, decode, execute, and store.

Summary (continued)

• The CPU’s performance is measured by the data bus width, operations per second, speed, and cache memory

• Random access memory (RAM) is the computer’s main memory. It is volatile.

• There are various types of RAM including dynamic RAM

48

• There are various types of RAM, including dynamic RAM(DRAM), synchronous DRAM (SDRAM), Rambus DRAM (RDRAM), and double data rate (DDR) SDRAM

• Computers have ports such as serial ports, parallel ports, SCSI ports, USB ports, FireWire ports, and IrDA ports to connect input/output devices

K.Ng Sept08

9

Input/Output and Storage

49

Input/Output and Storage

What You Will Learn About

The purpose of special keys and the most frequently used pointing devicesThe characteristics of a monitor’s quality and the various types of monitors

50

The two major types of printersThe difference between memory and storage

What You Will Learn About

The categories of storage devices The performance characteristics of hard drivesHow data is stored on both hard and floppy disksThe various optical storage media available for

51

The various optical storage media available for personal computers

Input

Input is any data entered into the computer’s memory

52

Input Devices: Giving Commands

Keyboard

Mouse

53

Other Pointing Devices

Keyboard

54

The keyboard allows the computer user to enter words, numbers, punctuation, symbols, and special function commands into the computer’s memory

K.Ng Sept08

10

Enhanced / Extended KeyboardErgonomic Keyboard

Types of KeyboardsWireless

Ergonomic Keyboard

55

Enhanced or Extended keyboard – Typically 101 keys laid out in the QWERTY fashion; connected to the computer by a cableCordless keyboard – Uses infrared or radio wave signalsErgonomic keyboard – Designed to help prevent Repetitive Strain Injury, or RSI

The Mouse

56

The mouse is the most widely used pointing device

A mouse is palm sized

As the mouse is moved, its movements are mirrored by the on-screen pointer

Wheel Mouse

Cordless Mouse

Types of Mice

57

Wheel mouse – Contains a rotating wheel used to scroll vertically within a text document; connects to PS/2 port or USB port

Cordless mouse – Uses infrared signals/RF/Bluetooth to connect to the computer.

Joystick

Touch ScreenTrackball

Pointing Sti k

Other Types of Pointing Devices

58

Touch Pad

Stick

PenTablet

Using the Mouse

Mouse buttons enable the user to initiate actions

Clicking (left-, right-, or double-clicking) allows the user to select an item on the screen or open a program or dialog box

59

Click and drag – Holding down the left mouse button and moving the mouse enables the user to move objects on the screen

Audio Input: Speech Recognition

Speech recognition is a type of input in which the computer recognizes words spoken into a microphone

Special software and a i h i d

60

microphone are required

Latest technology uses continuous speech recognition where the user does not have to pause between words

K.Ng Sept08

11

Scanners

Flatbed

Alternative Input Devices

Barcode reader

61

Monitors

A monitor is a peripheral device which displays

CRT LCD

62

A monitor is a peripheral device which displayscomputer output on a screenScreen output is referred to as soft copyTypes of monitors:

Cathode-ray tube (CRT)Liquid Crystal Display (LCD or flat-panel)

Cathode-ray tube (CRT)

Resemble televisions Use picture tube technologyLess expensive than a LCD

63

pmonitorTake up more desk space and use more energy than LCD monitors

Liquid Crystal Display (LCD)

Cells sandwiched between two transparent layers form imagesUsed for notebook computers, PDAs, cellular phones, and personal computersMore expensive than a CRT monitor

64

More expensive than a CRT monitor Take up less desk space and use less energy than CRT monitors

Monitor Specifications

Screen size – The diagonal measurement of the screen surface

65

Screen size The diagonal measurement of the screen surfacein inches (15, 17, 19, 21)Resolution – The sharpness of the image determined by the number of horizontal and vertical dots (pixels) that the screen can display (800 x 600, 1024 x 768, 1600 x 1200)Refresh rate – The speed at which the screen is redrawn (refreshed) and measured in Hertz (Hz) (60Hz, 75Hz)

Printers

A printer is a peripheral device that produces a physical copy or hard

66

physical copy or hardcopy of the computer’s output

K.Ng Sept08

12

Inkjet Laser

Types of Printers

Inkjet printer also called a Laser printer works like a

67

Inkjet printer, also called a bubble-jet, makes characters by inserting dots of ink onto paper Letter-quality printouts Cost of printer is inexpensive but ink is costly

Laser printer works like acopier Quality determined by dots per inch (dpi) producedColor printers available Expensive initial costs but cheaper to operate per page

Plotter

68

A plotter is a printer that uses a pen that moves over a large revolving sheet of paper

It is used in engineering, drafting, map making, and seismology

Hard Drive – storage RAM – memory

Memory vs. Storage

Storage also known as mass media or auxiliary storage

69

Storage, also known as mass media or auxiliary storage,refers to the various media on which a computer system can store data

Storage devices hold programs and data in units called files

Memory is a temporary workplace where the computer transfers the contents of a file while it is being used

Why Is Storage Necessary?

Storage devices:Retain data when the computer is turned off

Are cheaper than memory

70

Are cheaper than memory

Play an important role during startup

Are needed for output

A Bit of HD History

• Guess how big this HD can store?

71

IBM System 305: 1st computer with a hard drive in 1956

There were 50 24”∅ platters and could store 5MB!!!

Platter Read/Write head

Hard Disks

Hard disks are high-speed high-capacity storage devices

72

Hard disks are high speed, high capacity storage devices

They contain metal disks called platters

They contain two or more stacked platters with read/write heads for each side

Hard disks can be divided into partitions to enable computers to work with more than one operating system

K.Ng Sept08

13

More Hard Drives (I)

Removable Hard Disks (getting outdated)Platter is enclosed in a cartridge

Can be inserted into a drive bay

Secondary storage – storage that isn’t directly available

73

Internet Hard DrivesStorage space on a server

Subscription service

More Hard Disks (II)

Getting smaller (physical size) : e.g. Toshiba 0.85” 2-4GB HD in 2004.

And bigger (storage size) :

74

gg ( g )e.g. Hitachi 3.5” 1TB HD in 2Q 2007.

Or Both :e.g. Fujitsu 2.5” 300GB 4200rpm HD (MHX2300BT) in Feb. 2007e.g. Toshiba 1.8” 100GB 4200rpm HD in Jan. 2007

More Hard Disks (III)

Spins faster :e.g. Seagate’s 2.5” Savvio 15K Series HD 36GB/73GB at 15,000rpm.

75

Flash-memory based HD (Solid State Disks SSD)e.g. SanDisk’s 32GB 1.8” SSD in Jan. 2007 at about US$600.00

Factors Affecting a Hard Disk’s Performance

Seek time or positioning performance – How quickly the read/write head positions itself and begins transferring information. It is measured in milliseconds (ms)

76

milliseconds (ms)

Spindle speed or transfer performance – How quickly the drive transfers data. It is measured in rotations per minute (RPM)

Floppy and Zip Disks and Drives

A di k di k i bl di

Zip DriveFloppy Drive

Floppy Disk

77

A disk or diskette is a portable storage medium High-density floppy disks that are commonly used today store 1.44 MB of dataDisks work with a disk driveZip disks store up to 750 MB of data and are not downwardly compatible with floppy disks

Protecting the Data on Your Disks

Don’t touch the surface of the diskDon’t expose disk to magnetic fieldsAvoid contamination (food, drink)Avoid condensation

78

Avoid excessive temperatures

K.Ng Sept08

14

CD-ROM Discs and Drives

CD-ROM stands for Compact Disc-Read Only Memory

CD-ROM drives can not write data to discs

79

They are capable of storing 650 MB of data

They are used for storing operating systems, large application programs, and multimedia programs

CD-R and CD-RW Discs and Recorders

CD-RDiscs can be read and written toDiscs can only be

CD-RWDiscs can be read and written toDiscs are erasable

80

written to “once”CD-R drives are capable of reading and writing data

Discs can be written to many timesCD-RW drives are capable of reading, writing, and erasing data

DVD-ROM Discs and Drives

DVD stands for Digital Video DiscDVD technology is similar to CD-ROM technology

81

DVDs are capable of storing up to 17GB of dataThe data transfer rate of DVD drives is comparable to that of hard disk drives

DVD-RW and DVD+RW Discs

DVD-R and DVD+R drives have the ability to read/write data

DVD-RW and DVD+RW drives allow you to write, erase, and read from a disc many times

82

Protecting Data on Discs

Do not expose discs to excessive heatDo not touch underside of discsDo not write on the label side of discs with a hard instrument

83

Do not stack discsStore discs in original boxes

The Future of Optical Storage (1)

Blu-Ray Disc (BD)140 members: Sony, Samsung, LG, Walt Disney

Pictures, Twentieth Century Fox …etc.25GB/50GBSingle layer can hold >2 hrs. of HDTV

84

Single layer can hold 2 hrs. of HDTVblue-violet laser (405nm)

K.Ng Sept08

15

The Future of Optical Storage (II)

HD DVDDeveloped by Toshiba and NEC15GB/30GB

85

Solid State Storage Devices

Solid state storage devices use nonvolatile memory chips to retain data

They do not have moving parts

86

y g p

They are small, lightweight, reliable, and portable

Compact Flash (CF)

Secure Digital (SD) M

Smart Card

Memory Stick

Solid State Storage Devices

87

Flash (CF) Memory

(SD) Memory

USB Thumb Drives

Summary

• Input is the software, data, and information that is entered into the computer’s memory

• Input devices such as the keyboard, mouse, and trackball enable the user to enter data

• A pointing device enables the user to control f i

88

movements of an on-screen pointer • Speech recognition software enables the user to

enter data into a computer by speaking into a microphone

• Monitors enable the user to view the computer’s processed data; the output is known as soft copy

Summary (continued)• The two types of monitors are the CRT and the LCD• A monitor’s quality is measured by screen size, resolution, and

refresh rate• Printers produce permanent versions (hard copies) of the

computer’s output• The two basic types of printers are the inkjet and laser

M k ft d d t il bl f th CPU’

89

• Memory makes software and data available for the CPU’s use• Storage devices are categorized by:

Read-onlyRead/writeRandom accessNear online (secondary)

Summary (continued)

• A hard disk’s performance is measured by its positioning performance and transfer rate

• Optical storage devices include:CD-ROM– Read-onlyCD-R– Record onceCD-RW– Erasable, write repeatedly

90

DVD-ROM/DVD+ROM – Read-onlyDVD-R/DVD+R– Read/writeDVD-RW/DVD+RW – rewritten many times

• Solid state storage devices include:PC cardsFlash memory cardsSmart cards