1. 1 THE HONG KONG POLYTECHNIC UNIVERSITY Department of Electronic and Information Engineering ENG224 Information Technology Part I: Computers and Internet – Dr Daniel Lun, EIE Part II: Data Processing – Mr. S.M. Lau, COMP Part III: Networking – Dr Andy Leung, EIE

2. 2 THE HONG KONG POLYTECHNIC UNIVERSITY Department of Electronic and Information Engineering ENG224 Information Technology Part-I Computers and Internet Lecturer:Dr. Daniel Pak-Kong LUN Room: DE637 Tel: 27666255 E-Mail: enpklun@polyu.edu.hk Web page: www.eie.polyu.edu.hk/~enpklun/ENG224/ ENG224.html

3. 3 THE HONG KONG POLYTECHNIC UNIVERSITY Department of Electronic and Information Engineering Contents Introduction of Computers Operating System Case Study: Linux Internet Internet Programming - XHTML

4. 4 Information Engineering Information Technology Information Systems Electronic Engineering Mechanical Engineering Electrical Engineering System Engineering THE HONG KONG POLYTECHNIC UNIVERSITY Department of Electronic and Information Engineering

5. 5 An example – Mobile Banking Information Systems – To study the various issues in running and managing a mobile banking business e.g. Risk management, Organizational behavior, Psychologies of mobile customers, etc. Information Technology – To optimally integrate the required technologies to enable a mobile banking business e.g. Mobile Networking, Security control, Data processing for mobile transactions, etc. THE HONG KONG POLYTECHNIC UNIVERSITY Department of Electronic and Information Engineering

6. 6 An example – Mobile Banking (Cont) Information Engineering – To study the techniques required for the implementation of a mobile banking business e.g. Data transmission through mobile networks, Mobile handset design for data transmission, Data encryption algorithms, Database design and interface, etc. THE HONG KONG POLYTECHNIC UNIVERSITY Department of Electronic and Information Engineering

7. 7 Requirements of an IT Practitioner To understand the needs of the customers of different information systems and the organizations that provide those systems To know clearly well the attributes, limitations, strengths and the integration methods of the technologies that enable those information systems To understand the basic principles of the information engineering techniques for the implementation of those information systems THE HONG KONG POLYTECHNIC UNIVERSITY Department of Electronic and Information Engineering

8. 8 ComputerNetworking Data Processing Three basic elements of IT THE HONG KONG POLYTECHNIC UNIVERSITY Department of Electronic and Information Engineering

9. 9 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

10. 10 Reference Peter Norton, Introduction to Computers, McGraw Hill, 5 th Ed, 2003 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

11. 11 ENIAC The first practical computer Built in 1945, weighed more than 30 tons Require 1500 sq. feet In 1949, Popular Mechanics magazine predicted “computers in the future may perhaps only weigh 1.5 tons !!!” ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

12. 12 Components of a computer system ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

13. 13 Hardware ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

14. 14 Hardware CPU: Central Processing Unit – Brain of the computer – Manages all devices and performs the actual processing of data – Carry out instructions given by user – For Personal Computer (PC), the CPU is usually included in a single Integrated Circuit (IC) chip (called Microprocessor) – Nowadays, one or more microprocessors (chips) can be used to form a CPU  Parallel Processing ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

15. 15 Hardware Input and Output devices – Interface between the outside world and the computer system – Input devices: keyboard, mouse – Output devices: monitors, printers – Other I/O devices: network adapter, USB, disk interface … ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

16. 16 Hardware Memory – Internal memory / Main memory Random Access memory (RAM) – Main feature 1: volatile  requires continuous supply of electrical power to retain information – Main feature 2: cheap in terms of bytes per dollar  suitable for large volume data storage – Functions:  Receive commands / data from keyboard  Store info ready to be sent to output  Store currently running programs/their data  Store immediate data generated by the currently running programs ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

17. 17 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers Another kind of memory Read Only Memory (ROM) – Main feature 1: non-volatile  data retain even when the power is off – Main feature 2: relatively expensive and can only be written once  suitable for storing essential data but in small volume – Usually used for system boot up and basic control of I/O devices  When a computer first powers up, nothing is in RAM  Need ROM to store the instructions to set up various I/O devices, such as disk interface card, video adapter card, sound card, etc. – ROM is used to store BIOS (Basic Input/Output Systems)

18. 18 Hardware Storage devices – External memory Non-volatile Used to store programs/data for future use Also used when the capacity of the internal storage is insufficient to keep the currently running programs and the data required Floppy disks, hard disks, CD ROMs, Magnetic tapes ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

19. 19 Hardware Main differences between storage & memory: – Larger capacity in storage than in memory – Data in storage are retained while data in memory disappear when power is off – Storage is much cheaper than memory ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

20. 20 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers Instructions / Data CPU IDIII IIII IIIDD DDDDDD 00010203040506070809 10111213141516171819 Memory Address Control I/O I: Instruction D: Data Buses – Linking up the CPU, Memory and I/O devices 20 21 22 I/O External Storage

21. 21 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers Stored Program Concept – In 1949, Dr John Von Neumann defined the stored program concept that greatly affected the development of nowadays computers – Suggested that program instructions should be stored in a memory unit just like data  Instructions: Commands of user  Data: Information that commands work on – Hence rather than hardware programmable, should be software programmable

22. 22 Hardware - Instructions Most CPUs have built in a few hundreds of standard operations – E.g. add, subtract, multiplication, division, AND, OR, NOT, etc. Each operation is represented by an instruction code – E.g. Add 1010100101 – Subtract1000100001 – : When an instruction code is fetched from memory to the CPU, the CPU knows that the corresponding operation should be performed ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

23. 23 Hardware - Instructions A computer program is constructed by a combination of different instruction codes Called as Machine Language Program, since it is written by 0 and 1, the only language that the CPU can understand 0110001111000010 ; the 1st instruction 0001000111100011 ; the 2nd instruction : 0011000100001000; the n-1th instruction 1000001001010101; the nth instruction Machine Language Program ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

24. 24 Instructions / Data CPU IDIII IIII IIIDD DDDDDD 00010203040506070809 10111213141516171819 Memory Address Control I I ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers I/O I: Instruction D: Data Fetch and Execute – Every instruction should go through two phases of processing: fetch & execute 20 21 22 I 00 R R FETCH EXECUTE CPU 01 R R FETCH 05 W D W D EXECUTE 02 R R FETCH I/O 20 W D D W EXECUTE I/O

25. 25 Fetch – Send address 01 to address bus – Send control signal Read – Get instruction I at address 00 Execute – Send address 05 to address bus – Send data D to data bus – Send control signal Write Example ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

26. 26 Software - Programming Programming – the way to generate a program Computer can only understand 0 and 1 The most direct way to communicate with the computer is to use 0 and 1  Machine Language Programming 0110001111000010 0001000111100011 : 0011000100001000 1000001001010101 Machine Language Program Very tedious and can make error easily ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

27. 27 Software - Assembly Language Programming Assembly Language is created to help human instructs CPU to work By using a tool called Assembler, assembly language program can be converted into machine language program Assembler 0110001111000010 0001000111100011 : 0011000100001000 1000001001010101 mov ax, #0 add ax, $1234 : mov bx, #22 mov $2345, bx Assembly LanguageMachine Language ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

28. 28 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers Different CPU will have different set of assembly language codes In fact, to understand an assembly language program, we need to first understand the architecture of the CPU ALU: Arithmetic and Logic Unit : For doing arithmetic and logic operation) Registers: Some very fast memory inside the CPU chip Memory CPU ALU Registers ax bx cx dx

29. 29 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers Memory CPU ALU Registers ax bx cx dx A sample assembly language program mov ax, #0 ; ax =0 loop:add ax, $1234 ; add the content at memory ; address 1234 to ax mov bx, #22 ; bx = 22 add ax, bx ; ax = ax + bx jmploop ; go to the instruction with ; label “loop”

30. 30 Software - High Level Language Programming Assembly language programming is still too complicated for general users They are far from human used language e.g. “Set W equal to W plus X minus Y divided by Z” “Repeat the next sequence of instructions until X is less than 0 or Y equals Z” A high level language is required to close the gap between human and computers ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

31. 31 main() { cout << “Hello!”; } Compiler Linker 1011010101 0101010101 : High Level Program Executable Machine Language Program Object code Library ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

32. 32 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers Machine Language Programming – No application nowadays Assembly Language Programming – Advantage: Less complicated than Machine Language. Usually generate more efficient code than HLL – Disadvantage: Need the understanding of CPU structure. Still difficult to program – Application: Sometimes use in the programming of embedded systems (e.g. CPU of printer, washing machines, etc.) High Level Language Programming (such as C/C++) – Advantage: Need the least amount of effort to write a program – Disadvantage: The program written may not be optimal (depends on the compiler) – Application: For large scale programs

33. 33 Banking System / Web Browser / Media player Hardware & Software Physical devices / Micro-architecture level Operating System GUI / Command interpreter Application Software System Software Hardware ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

34. 34 ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers User interacts with application software System software enables the application software to interact with computer CPU and help the computer to manage its internal resources (hardware)

35. 35 Application Software Develop to fulfill certain needs of users Either customized or packaged – Customized software Designed for a particular customer according to their needs Payroll, inventory control, … – Packaged software Developed for general use Microsoft word, excel, Access, power-point, … ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

36. 36 System Software Exists primarily for the computer itself Hides the hardware complexities Brings the different hardware configurations into common platforms and accessible by the users Consists of several programs, the most important one is the operating system (master control program that runs the computer) ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers

37. 37 Operating System Master control program – Manage all resources of the computer CPU, memory, disk, monitor, network, … – Co-ordinate running programs Runs as soon as the computer boots up, until the computer shuts down Usually store in the hard disk and load into the memory when the computer starts Need the help of BIOS for I/O devices E.g. Windows, Unix, Linux ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers BIOS Operating System I/O Devices Other resources

38. 38 When power up, nothing is in RAM. No control is possible to the hard disk to load the OS CPU starts to read the BIOS instructions stored in the ROM Things that normally perform –Initialize all I/O devices: hard disk, video, mouse, keyboard, CD-ROM, etc –Load the bootstrap loader of the operating system to RAM –Start to execute the bootstrap loader in RAM The bootstrap loader further loads the other part of the operating system to the RAM ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers How the OS is loaded into memory?

39. 39 CPU Main Memory (RAM) BIOS (Stored in ROM) Hard Disk Mother Board Disk Interface Video Interface Monitor Disk Interface Video Interface Bootstrap loader OS ENG224 INFORMATION TECHNOLOGY – Part I 1. Introduction to Computers