Introduction To Computer Science PDF

Introduction to Computer Science By Dr. Ahmed Taha Lecturer, Computer Science Department, Faculty of Computers & Informatics, Benha University 1  Book Contents #...

Introduction to Computer Science By Dr. Ahmed Taha Lecturer, Computer Science Department, Faculty of Computers & Informatics, Benha University 1  Book Contents # Chapter Title 1 Computers and Digital Basics 2 Computer Hardware 3 Computer Software 4 Operating Systems and File Management 5 Local Area Networks 6 The Internet 7 The Web and E-mail 8 Digital Media 9 The Computer Industry: History, Careers, and Ethics 10 Information Systems Analysis and Design 11 Databases 12 Computer Programming 5 LOGO Computers and Digital Basics 6  Contents 1 All Things Digital 2 Digital Devices 3 Digital Data Representation 4 Digital Processing 7 LOGO All Things Digital 8 LOGO  The Digital Revolution  Digital Revolution is an ongoing process of social, political, and economic change brought about by digital technology, such as computers and the Internet.  Information Age is a period in history when information is easy to access and affects many aspects of everyday life, from the economy to politics and social relationships. 10 LOGO  The Digital Revolution  Digitization is the process of converting text, numbers, sound, photos, and video into data that can be processed by digital devices.  The significant advantage of digitization is that things as diverse as books, movies, songs, conversations, documents, and photos can all be distilled down to a common set of signals that do not require separate devices. 11 LOGO  When did the Digital Revolution Begin  Engineers built the first digital computers during World War II (1939 to 1945) for breaking codes and calculating missile trajectories.  In the 1950s, computers were marketed for business applications, such as payroll and inventory management.  Some historians mark the 1980s as the beginning of the digital revolution 12 LOGO  The Digital Revolution Phases Data Processing Personal Computing Network Computing Cloud Computing Computers Computers Personal became were huge, computing Cloud networked. complex, and Model is computing Network expensive presented. provides access technology devices. Computers to information, allowed to They existed in were not applications, connect in big connected to communication, multiple corporations networks, so and storage computers, and and government they were over the share the agencies essentially self- Internet Internet contained units connection 13 LOGO  Phase I: Data Processing  Data Processing is the computing model for the first phase of the digital revolution. 14 LOGO  Phase II: Personal Computing  The first personal computers were made in 1976.  The most popular uses for personal computers were word processing and gaming; sound systems and graphics capabilities were primitive. 15 LOGO  Phase II: Personal Computing  Personal Computer is characterized by small, standalone computers powered by local software.  Local software refers to any software that is installed on a computer’s hard drive.  On the business, large computers continued to run payroll, inventory, and financial software.  Some managers used personal computers and spreadsheet software to crunch numbers for business planning. 16 LOGO  Phase III: Network Computing  A Computer Network is a group of computers linked together to share data and resources.  The Internet is a global computer network originally developed as a military project.  The Web (short for World Wide Web) is a collection of linked documents, graphics, and sounds that can be accessed over the Internet. 17 LOGO  Phase III: Network Computing  Computers were the primary devices for accessing the Internet during the period from 1995–2010, but applications, media, and data remained on the local hard disk. 18 LOGO  Phase IV: Cloud Computing  The “cloud” represents Internet based services, such as applications and social media, that are available from computers and handheld digital devices. 19 LOGO  Phase IV: Cloud Computing  With cloud computing, you can use your browser to access word processing applications that run from the Internet, instead of software that you have installed on your local hard disk.  You can use online applications to manage your e-mail, create floor plans, produce presentations, and carry out a host of other activities.  You can store your data in the cloud, too, making it available no matter what computer you’re using as long as it has an Internet connection. 20 LOGO  Phase IV: Cloud Computing  Social Media are cloud-based applications designed for social interaction and consumer-generated content.  They include social networking services, wikis, blogging services, photo sharing services, and microblogging sites 21 LOGO Digital Devices 22 LOGO  Computer Basics  A Computer is a multipurpose device that accepts input, processes data, stores data, and produces output, all according to a series of stored instructions from a computer program. 23 LOGO  Computer Basics  Input is whatever is typed, submitted, or transmitted to a computer system.  Output is the result produced by a computer.  Data refers to the symbols that represent raw facts, objects, and ideas.  When data is processed, organized, structured or presented in a given context so as to make it useful, it is called Information. Data Data  Data is used by machines, such as Data computers; information is used by humans Information 24 LOGO  Computer Basics  In a computer, most processing takes place in a component called the Central Processing Unit or CPU.  The CPU of most modern computers is a microprocessor, which is an electronic component that can be programmed to perform tasks based on data it receives unsorted list sorted list 25 LOGO  Computer Basics  Memory is an area of a computer that temporarily holds data waiting to be processed, stored, or output.  Storage is the area where data can be left on a permanent basis when it is not immediately needed for processing.  File is a named collection of data that exists on a storage medium, such as a hard disk, CD, DVD, or flash drive. 26 LOGO  Computer Basics  Computer Program is a series of instructions that tells a computer how to carry out processing tasks.  These programs form the software that sets up a computer to do a specific task.  When a computer “runs” software, it performs the instructions to carry out a task 27 LOGO  Computer Basics Software Types Application System Software Software A set of It helps the computer computer programs system monitor itself in that helps a person order to function carry out a task efficiently Ex. Word Processing Ex. Operating System 28 LOGO  Computer Types Computer Types Personal Servers Mainframes Supercomputers Computers 29 LOGO  Computer Types  Personal Computer is a microprocessor-based computing device designed to meet the computing needs of an individual.  It commonly includes a keyboard and screen. 30 LOGO  Computer Types  The term workstation has two meanings:  It can simply refer to an ordinary personal computer that is connected to a network.  A second meaning refers to powerful desktop computers used for high-performance tasks, such as medical imaging and computer- aided design, that require a lot of processing speed.  Typically, it costs a bit more than an average personal computer. 31 LOGO  Computer Types  The term Server has several meanings. It can refer to computer hardware, to a specific type of software, or to a combination of hardware and software.  The purpose of a server is to serve computers on a network (such as the Internet or a home network) by supplying them with data.  Any software or digital device, such as a computer, that requests data from a server is referred to as a client 32 LOGO  Computer Types  Any personal computer, workstation, mainframe, or supercomputer can be configured to perform the work of a server.  Server does not require a specific type of hardware.  However, computer manufacturers such as IBM, SGI, HP, and Dell offer devices called servers that are especially suited for storing and distributing data on a network 33 LOGO  Computer Types  Mainframe Computer is a large and expensive computer capable of simultaneously processing data for hundreds or thousands of users.  Mainframes are generally used by businesses or governments to provide centralized storage, processing, and management for large amounts of data.  Mainframes remain the computer of choice in situations where reliability, data security, and centralized control are necessary. 34 LOGO  Computer Types  Supercomputer is one of the fastest computers in the world.  Because of their speed, supercomputers can tackle complex tasks and compute-intensive problems that just would not be practical for other computers.  Common uses for supercomputers include breaking codes, modeling worldwide weather systems, and simulating nuclear explosions. 35 LOGO  Microcontroller  A microcontroller is a special- purpose microprocessor that is built into the machine it controls.  Sometimes, it is called a computer- on-a-chip or an embedded computer because it includes many of the elements common to computers.  It controls your microwave oven, digital video recorder, washing machine, and watch 36 LOGO Digital Data Representation 37 LOGO  Data Representation Basics  Data Representation refers to the form in which data is stored, processed, and transmitted.  Data can be represented using digital or analog methods.  Digital data is text, numbers, graphics, sound, and video that have been converted into discrete digits such as 0s and 1s.  In contrast, analog data is represented using an infinite scale of values. 38 LOGO  Data Representation Basics  The 0s and 1s used to represent digital data are referred to as binary digits.  A bit (binary digit) is a 0 or 1 used in the digital representation of data.  Numeric data consists of numbers that can be used in arithmetic operations.  Digital devices represent numeric data using the binary number system. 39 LOGO  Data Representation Basics  Character data is composed of letters, symbols, and numerals that are not used in arithmetic operations.  Digital devices employ several types of codes to represent character data, including ASCII, EBCDIC, and Unicode. 40 LOGO  Data Representation Basics  ASCII (American Standard Code for Information Interchange, pronounced “ASK ee”) requires only seven bits for each character. (codes for 128 characters) 41 LOGO  Data Representation Basics  EBCDIC (Extended Binary-Coded Decimal Interchange Code, pronounced “EB seh dick”) is an 8-bit code used only by older, mainframe computers. 42 LOGO  Data Representation Basics  Extended ASCII is a superset of ASCII that uses eight bits to represent each character. (codes for 256 characters) 43 LOGO  Data Representation Basics  Unicode (pronounced “YOU ni code”) uses sixteen bits and provides codes for 65,000 characters  It is a real bonus for representing the alphabets of multiple languages. 44 LOGO  Data Representation Basics  Images (such as photos, pictures, line art, and graphs) are digitized by treating them as a series of colored dots.  Each dot is assigned a binary number according to its color. 45 LOGO  Data Representation Basics  Sound (such as music and speech) is characterized by the properties of a sound wave. 46 LOGO Quantifying Bits and Bytes 47 LOGO  Circuits and Chips  Bits are represented with two states of an electric circuit.  1 bit would be on and the state for a 0 bit would be off.  In practice, the 1 bit might be represented by an elevated voltage, such as +5 volts, whereas a 0 bit is represented by a low voltage, such as 0.2) 48 LOGO  Circuits and Chips  An Integrated Circuit (IC), (computer chip, microchip), is a super-thin slice of semiconducting material packed with microscopic circuit elements, such as wires, transistors, capacitors, logic gates, and resistors. 49 LOGO  Circuits and Chips  Integrated circuits are packaged in protective carriers that vary in shape and size. DIP (dual in-line package) PGA ((pin-grid arrays) 50 LOGO  Circuits and Chips  The electronic components of most digital devices are mounted on a circuit board called a system board, motherboard, or main board.  The system board houses all essential chips and provides connecting circuitry between them. 51 LOGO Circuits and Chips 52 LOGO Digital Processing 53 LOGO  Programs and Instruction Sets  Computer programmers create programs that control digital devices.  These programs are usually written in a high-level programming language, such as C, BASIC, COBOL, or Java.  Programming languages use a limited set of command words such as Print, If, Write, Display, and Get to form sentence-like statements designed as step-by-step directives for the processor chip. 54 LOGO Programs and Instruction Sets 55 LOGO  How does source code get converted?  A compiler converts all the statements in a program in a single batch, and the resulting collection of instructions, called object code, is placed in a new file. 56 LOGO  How does source code get converted?  An interpreter converts and executes one statement at a time while the program is running. After a statement is executed, the interpreter converts and executes the next statement, and so on 57 LOGO  How does source code get converted?  A microprocessor is hard-wired to perform a limited set of activities, such as addition, subtraction, counting, and comparisons.  This collection of preprogrammed activities is called an instruction set  Each instruction has a corresponding sequence of 0s and 1s.  The list of codes for a microprocessor’s instruction set, called machine language, can be directly executed by the processor’s circuitry. 58 LOGO  How does source code get converted?  A machine language instruction has two parts: the op code and the operands.  An op code, which is short for operation code, is a command word for an operation such as add, compare, or jump.  The operand for an instruction specifies the data, or the address of the data, for the operation. Op code Operand 59 LOGO  How does source code get converted?  A single high-level instruction very often converts into multiple machine language instructions. 60 LOGO  How does source code get converted?  A programmer creates human-readable source code using a programming language.  A compiler or an interpreter converts source code into machine code.  Machine code instructions are a series of 0s and 1s that correspond to a processor’s instruction set. 61 LOGO  What happens inside a computer chip?  The ALU (Arithmetic Logic Unit) is the part of the microprocessor that performs arithmetic operations, such as addition and subtraction.  It also performs logical operations, such as comparing two numbers to see if they are the same.  The microprocessor’s control unit fetches each instruction; Data is loaded into the ALU’s registers. Finally, the control unit gives the ALU the green light to begin processing, 62 LOGO  Instruction Cycle  The term instruction cycle refers to the process in which a computer executes a single instruction. 63 LOGO Instruction Cycle 64 LOGO Instruction Cycle 65 LOGO 66