Unit-I Historical Development

Unit-I Historical Development Introduction to Computer The word “computer” comes from the word “compute”, which means, “to calculate”. Hence, a computer can be considered as a calculating device that can perform arithmetic operation at high speed. A computer is often referred to as a “data processor” because it can store, process, and retrieve data whenever desired (see figure 1). Output Input Data Computer (Data Processor) Information Figure 1:- A computer converts data into information Characteristics of Computer The main characteristics of a computer are given bellow: a) Automatic: It carries out a job normally without any human intervention. b) Speed: It can perform several billion and even trillion simple arithmetic operation per second. c) Accuracy: It performs every calculation with the same accuracy. d) Diligence: It is free from monotony, tiredness and lack of concentration. e) Versatility: It can perform a wide variety of tasks. f) Storage: They have a large amount of memory to hold a very large amount of data. g) Power of Remembrance: A computer can remember and recall data because of its capacity to hold data. h) No Feelings: A computer is completely lacking of emotions. They cannot make judgments based on feelings. History (Evolution) of Computer The history of computer can be classified into different eras: Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 1 a) First Era (Pre-Mechanical Era): In this era, simple tools were used for calculation. Counting was done using stones and keep records. Around 500BC, a simple counting tool called Abacus was invented in China. It would perform all arithmetic operations like addition, subtraction, multiplication and division. Invention of logs by John Napier allow multiplication and division to be reduced to addition and subtraction, where the logarithm values were carved (cut up) on ivory (bone) sticks which are now called Napier‟s Bones. b) Second Era (Mechanical Era): This period is called mechanical because the machines were based on moving parts and they didn‟t have any logical control in operation. In 1642, at the age of 19, Blaise Pascal of France, created a gear driven adding machine named Pascaline as an aid for his father who was a tax collector. Later in 1671, Leibniz of Germany invented a first calculator for multiplication. It was similar to Pascal‟s calculating machine but more reliable and accurate. Charles Babbage proposed a steam driven calculating machine having the size of a room in 1822, which he called the Difference Engine. This machine was able to compute tables of numbers. And his next brainstorm, which he called the Analytical Engine. This device had several features including provisions for inputting data, storing information, performing arithmetic calculations and printing out results which are also found in modern computers. Analytical engine provided the foundation for the modern computer. Therefore, Charles Babbage is known as the father of modern computer. In 1842, Lady Augusta Ada wrote the first program for the difference engine made by Babbage. Therefore, Ada earned her spot in history as the first computer programmer. c) Third Era (Electro-Mechanical Era): The end of Mechanical Era occurred when physics paved (covered) the way for electrical innovation. The beads of the abacus were replaced by bits in the modern computer. Essentially a bit (binary digit) is a small electrical charge that represents a 1 or 0. Since, both the electrical and mechanical components were used, this era is known as electro-mechanical era. In 1890, an American scientist Herman Hellerith developed punched card and used as input media in computer. In 1939, Atanasoff and Berry developed a computer called ABC (Atanasoff and Berry Computer). In this computer, 45 vacuum tubes were used for performing internal logic operations and capacitors were used for internal data storage. In 1944, an American professor Howard Aiken designed first fully automatic calculating machine. It was named as Mark-I. This calculating machine operated under the control of given instructions. d) Fourth Era (Electronic Era): This era is fully driven by electronic devices as components of computer. The first electronic computer, ENIAC (Electronic Numerical Integrator And Calculator) was built in 1946. It contained about 18,000 vacuum tubes and occupied more than 1,500 square feet with weight of 30 tons. The ENIAC was Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 2 programmed by physically connecting electrical wires in the proper order. It is very difficult to detect errors and to change the program and also stores limited amount of data. An altering and entering program into ENIAC was very tedious. To overcome this problem, a new concept of stored program was presented by John Von Neumann called EDVAC (Electronic Discrete Variable Automatic Computer). According to the Von Neumann theory, data and program can be stored in the same memory of the computer and automatically performs the operations. In 1951, UNIVAC-1 (Universal Automatic Computer) was developed and which also called first digital computer. In 1952, the IBM (International Business Machine) corporation introduced the 701 commercial computers which was improved version of UNIVAC-1. Generations of Computers The term generation indicates the stages of evolution or development of computers based on the type of technology used in the construction of computer over a period of time. The computers in electronic era are divided into different generations: a) First Generation (Vacuum Tubes): In this generation vacuum tubes were used for electrical current flow between electrodes and magnetic drums for memory. Punch card was used for input and printout display for output. This generation computers used machine language with limited storage capacity. Examples: ENIAC, EDVAC, UNIVACI, IBM 650 etc. b) Second Generation (Transistors): The transistor technology was used in this generation. The transistor is smaller in size, fast and more reliable than vacuum tube. Therefore, the transistor technology was used in computer in place of vacuum tube technology. This generation computer used assembly language with large storage capacity. Transistor technology reduced size and price of a computer. Examples: IBM 1401, IBM 7030, GE 635(General Electric 635) etc. c) Third Generation (Integrated Circuits): In this generation, integrated circuits (IC) were used for memory and processing units. Many transistors are placed on a single IC, which drastically change the speed and efficiency of the computers. Small Scale Integration (SSI: which includes around 10 transistors in a single IC) and Medium Scale Integration (MSI: which includes around 100 transistors in a single IC) technologies were used for memory and processor units. Keyboard was used as input and monitor as output. These computers started to use operating system (OS) and high level language. Examples: IBM 360, PDP-8 Series (Programmable Data Processor-8 Series) etc. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 3 d) Fourth Generation (Microprocessors): In this generation, Large Scale Integration (LSI: thousands of transistor on a single chip) and Very Large Scale Integration (VLSI: hundred of thousands of transistors on a single chip) technologies were used for processor units. These developments were followed by creation of microprocessors. These computers support versatile inputs and outputs and also use fourth generation language (4GL). Examples: IBM PCs, Intel PCs, Macintosh PCs etc. e) Fifth Generation (Artificial Intelligence): Computers based on Artificial Intelligence (AI) are known as fifth generation computers. These computers use Ultra Large Scale Integration (ULSI) technology and hence capable of calculating billions of operations in a second. AI uses expert system, which is software package and enables thinking and making decision on the basis of rules setup by human specialist. It uses knowledge based problem solving techniques and uses AI programming tools (PROLOG and LISP). Types of Computers Computers can be classified based on their processing speed, amount of data hold, purpose of the computer and working principle. Depending upon their operating principle or working principle computers are divided into three categories; which includes instructions and form of input data that they accept and process. These are: a) Analog Computers: The word analog means continuously varying in quantity. The analog computers accept input data in continuous form and output is obtained in the form of graph. The voltage, current, sound etc. are examples of analog signal. These values continuously increase or decrease. The analog computers have low memory size and have fewer functions. These computers are very fast in processing but output return is not very accurate. Example: Polish analog computer AKAT-1, Differential Analyzer etc. b) Digital Computers: The word digital means discrete (Individually separate and distinct). It refers to binary system, which consists of only two digits i.e. 0 or 1. Digital data consists of binary data represented by OFF (low or 0) and ON (high or 1) electric pulses. In digital computers, quantities are counted rather than measured. Accurate result and high speed data processing are the main features of digital computers. Example: Calculators, personal computers, digital watches etc. c) Hybrid Computers: The hybrid computer combines best features of both analog and digital computers. In these computers, the users can process both the continuous (analog) and discrete (digital) data. These are special purpose computers for scientific fields. These are very fast and accurate. Examples: Computer is in ICU (Intensive Care Unit), computer used in Missile etc. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 4 Unit-II Introduction to Computer Systems Fundamental concepts of Computers Computer is an electronic machine that is used to solve different kinds of problems. Generally, computer is divided into two sub systems: i. Computer Software: A set of instructions given to the computer is known as computer software. The software tells the computer what to do and how to perform the given task of the user. Although the range of software is vast and varied, most software can be divided into two major categories: Users Application Software System Software Hardware Figure: Software and Hardware Relationship   ii. System Software: It is a term referring to any computer software whose purpose is to help run the computer system. Most of them are responsible for directly controlling individual hardware components of computer systems. Specific kinds of system software include operating system (OS), device driver, utility program (formatting of disk, removing bugs from program). Examples: DOS (Disk Operating System), Windows, Linux etc. Application Software: It is a set of one or more programs, which solves a specific problem. It includes programs that do real work for users. Example: Word Processors, Spreadsheets etc. Computer Hardware: The physical parts of a computer are known as computer hardware. We can touch, see and feel the hardware. The hardware components are keyboard, mouse, hard disk, CPU, printer etc. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 5 Firmware Firmware is a type of software that provides control, monitoring and data manipulation of engineered products and systems. Typical examples of devices containing firmware are embedded systems (such as traffic lights, consumer appliances, remote controls and digital watches). Block Diagram of Digital Computer A digital computer is capable of performing various tasks and can be illustrated with the help of following block diagram: Memory Unit Secondary Memory Output Input Primary Memory Control Unit A L U R CPU Figure: Block diagram of a digital computer The different components of a typical digital computer and their major functions are described below. i. Input Unit: The input unit is a device that is used to feed the data and instructions into the computer. Keyboard and mouse are commonly used as input devices. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 6 ii. iii. iv. Output Unit: An output unit provides the information and results of a computation to outside world. The output device gives the desired result to the user. Example: Monitor, Printer etc. Central Processing Unit (CPU): CPU is a major component of any computer. It performs all the processing related activities. It receives data and instructions from outside world, stores them temporarily, processes the data as per the instructions and sends the result to the outside world as information. The CPU is a combination of three components Arithmetic and Logical Unit (ALU), Control Unit (CU) and Register Array (R). a. Arithmetic Logic Unit (ALU): It contains electronic circuits necessary to perform all the arithmetic and logical operations. The arithmetic operations include addition, subtraction, multiplication, division etc. Similarly, logical operations include logical AND, OR, complement, Shift etc. b. Control Unit (CU): It controls all other units in the computer. It controls the flow of data and instruction to and from memory (or I/O) to ALU. The main tasks of the CU are to fetch, decode and execute of an instruction and control & synchronizes its working. c. Register Array (R): CPU contains special purpose temporary storage locations called registers. Registers quickly accept, store and transfer data and instructions. Number of registers like Accumulator, Stack Pointer, Address register etc. are contain in CPU to form register array. Memory Unit: It is the location where data and instructions are stored. Memory is the main storage unit in a computer. Memory can be divided into two parts: a. Primary Memory: It is the main memory of the computer. It stores and provides information very quickly. Example: RAM, ROM etc. b. Secondary Memory: It has very large storage capacity and used as a backup memory for future reference. Example: Hard Disk, Floppy Disk etc. Memory It is one of the major components of computer system. It can be internal or external. CPU registers, cache memory, buffer, RAM, ROM, Hard Disk, Floppy Disk, Magnetic tape etc. are all memory devices used for storing data and instructions. Memory can be divided into two parts: i. Primary Memory or Main Memory: Primary memory can be volatile and non-volatile. RAM is volatile which means it forgets all data while computer is turned off. The ROM which holds data even if computer is turned off and hence is non-volatile. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 7 a. RAM (Random Access Memory): It is considered “random access” because any data in the memory can be directly access in any order. RAM also refers to read and write memory. RAM can be further divided into DRAM and SRAM.  DRAM (Dynamic RAM): It is the most common type of RAM used to store data and instructions in computer. It has memory cells with pair of transistor and capacitors requiring constant refreshing.  SRAM (Static RAM): It uses multiple transistors (or flip-flops) typically four to six for each memory cell but doesn‟t have a capacitor so doesn‟t need refreshing circuits. b. ROM (Read Only Memory): The ROM contains instructions or programs that are permanently stored on the chips by the manufacturer themselves. The instruction stored in ROM can only be read but can‟t be modified. The programs stored in a ROM are called firmware. The ROM contains the Basic Input/Basic Output (BIOS) which is a set of instructions that are automatically activated when computer is turned on. ROM can be further divided into PROM, EPROM and EEPROM:  PROM (Programmable ROM): PROM is a blank chip on which the user can write his own program instructions and data but only once and then can‟t be changed.  EPROM (Erasable PROM): It is similar to the PROM but program can be erased and reprogrammed by exposing the chip into high intensity ultraviolet light for 10 to 20 minutes.  EEPROM (Electrically EPROM): It is a special type of PROM that can be erased by exposing it to a relatively high voltage of an electric charge on byte by byte within millisecond range of time and can be reprogrammed up to 10000 times. ii. Secondary Memory or Auxiliary or Backup Memory Secondary memory is known as auxiliary memory or simply the storage. It is non-volatile and can stored data on long term basis for future use. The presence of magnetic field represents a „1‟ bit and its absence represents a „0‟ bit. Some of the main secondary memory devices are: a. Magnetic Storage: It refers to keep information or data on magnetized materials. The surface of magnetic storage is coated with millions of tiny iron particles so that data can be stored on them. There are two types of magnetic storage: i. Magnetic Disk: Magnetic disk is commonly used in computers as secondary memory. A magnetic disk is a circular metal or plastic disk coated on both sides with magnetic recording material (ferrous oxide). The data on magnetic disk is recorded on both sides of the disk and as magnetic fields. There are two fundamental types of magnetic disks. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 8  Floppy Disk: The floppy disk is a thin and flexible plastic disk coated both side with magnetic recording material (ferrous or iron oxide).  Hard Disk: It is a most commonly used storage device in personal computers and laptops. It includes the hard disk, and the motor that rotates the platter. The hard disk and drive is a single unit. ii. Magnetic Tape: It is the most popular and oldest storage medium used to store large amount of data and instructions permanently. The magnetic tape is a plastic ribbon with width 0.25 inch to 1 inch and one side coated with magnetic material (ferrous oxide or iron oxide). b. Optical Storage: Today, the most widely used and reliable storage devices are the optical storages. These devices use laser technology. The most popular optical storage devices are CD-ROM, DVD-ROM etc. c. External Storage: The storage devices which can be connected to the system externally are called external storage devices. Some of the commonly used external devices are: Flash Memory, Portable Hard Disk etc. Cache Memory Cache is a relatively small and fastest memory located between CPU and main memory. The main objective of cache memory is to reduce the average cost (time or energy) to access data from the main memory. There are basically different levels of caches. For example: L1, L2 and L3 caches. Buffer Buffer is a memory which is used for an uninterrupted flow of information, especially, when there is faster device transferring the data to a slower device. Peripheral Devices A peripheral device is generally defined as any auxiliary device such as a computer mouse or keyboard that connects to and works with the computer in some way. Peripheral devices provide the means of communication between the computer and the user. These devices are also called input-output (I/O) devices. There are three different types of peripherals: a. Input Devices: These devices interact with or send data from the user to the computer. For examples: mice, keyboards, digitizer, joystick, electronic pen etc. b. Output Devices: These devices provide output to the user from the computer. For examples: monitors, printers, projector, plotter etc. c. Input/Output Devices: These devices perform both input and output functions. For examples: touchscreen, headset, network card etc. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 9 Unit-III Programming Preliminaries Introduction to Program Basic commands that instruct the computer system to do something are called instructions. An organized list of instructions that, causes the computer to behave in a predetermined manner is a program. Introduction Programming Language Similar to our natural languages Nepali, English etc. used to communicate among each other. Likewise, if we want to communicate with computer we use language. Such type of language which instructs computer to perform user specified task is called programming language. Therefore, programming language is a standardized communication technique for describing instructions for a computer. Programming languages are classified mainly into two categories on the basis of creating instructions: a. Low Level Language: These are much closer to hardware. A program can‟t be run on different hardware and these are specific to hardware. Low level language is also divided into two types: i. Machine Language: It is the lowest level language because it uses strings of 0‟s and 1‟s in the form of voltage to give instructions and data to the computers. There was no translator used to compile or assemble this language. However, it is very difficult to learn machine language and also tough task to debug errors. For example: 1000001; this is the sequence of 1‟s and 0‟s. ii. Assembly Language: An assembly language contains the English short abbreviation called mnemonics rather than sequence of 0‟s and 1‟s. It is easier to understand than the machine level language. For example: ADD A, B; which means it adds values of A and B and stores result into A. To translate assembly language into machine code translation software (or program) is required, which is called assembler. b. High Level Language: The languages are called high level language if their syntaxes are closer to human language. Most of the high level language uses English like languages and make easier to program. High level languages are sometimes used to refer all languages above assembly level language. Which are: i. Procedural Oriented Languages: These languages are very close to the human languages. Because English like language, it takes very less time to write code and debug the errors. These languages are called procedural because the procedure (or function) of the program i.e. instructions of language is process step by step. Examples: FORTRAN, C, C++ etc. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 10 ii. iii. Problem Oriented Languages: These languages are more closer to human than procedural language by making computer to process much like as human behavior. These languages especially focused on database management systems. Examples: SQL, ORACLE etc. Natural Languages: Natural languages are those which we use in our daily activities. The main objectives of the natural languages are to make the connection between human and computer more natural and to make the machine smarter. Examples: PROLOG (Programming Logic) and LISP (List Processing). Generation of Programming Language Generation of programming language is based on increasing power of programming styles. There are basically five programming language generations: 1. 2. 3. 4. 5. First Generation Language (1GL) : Machine Language Second Generation Language (2GL) : Assembly Language Third Generation Language (3GL) : Procedural Oriented Language Fourth Generation Language (4GL) : Problem Oriented Language Fifth Generation Language (5GL) : Natural Language Program Design Methodology The development of program is not straight forward as it seems at first sight. The programmer must have a detailed knowledge of the programming language; understand the facts and problems, objectives and users of the program. Program designing or developing process follows almost the same steps as any problem solving task. There are five major steps in the process of program designing methodology. They are: 1. Defining the problem: It involves problem analysis, specifying the input, process and output required. 2. Planning the solution: It is a structure or detail design phase. Programmer plans the solution of the given problem using standard program development tools. 3. Coding the program: On the basis of planned solution, programmer codes the computer program on the computer. 4. Testing the program: This phase covers the testing and modification of solution. 5. Documenting the program: In this phase, detail documentation of the solution is presented. The commonly used program development tools are algorithm, flowchart, and pseudo code. One or more of these tools can be used while designing the program. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 11 Stages of Software Development Software development is a process of splitting software development work into distinct phases (or stages) containing activities with the intent of better planning and management. It is often considered a subset of the Systems Development Life Cycle (SDLC). Basic software development process can be described by waterfall model. It includes following stages: 1. Requirements Analysis: It collects information from end users and stakeholders then analyze how much idea or information put into action for development of software. In this phase detail blueprint of various phases is developed. 2. Software Design: In this phase design of the system is designed. The system analyst design the logical designer for the system designer and designer designs back end and front end both. 3. Implementation: It is the realization of an execution of a plan, design, specification, or policy. It implements design in real world. 4. Testing and Verification: Software testing involves the execution of a software component or system component to evaluate one or more properties of interest. 5. Deployment: Once the functional and non-functional testing is done, the product is deployed in the customer environment or released into the market. 6. Maintenance: It is the modification of a software product after delivery to correct faults, to improve performance or other attributes. A common perception of maintenance is that it merely involves fixing defects. The waterfall model is a sequential development approach, in which development is seen as flowing steadily downwards (like a waterfall), through several phases as depicted below: Analysis Design Implementation Testing & Verification Deployment Maintenance Figure: Waterfall Software development model. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 12 Text Editor A text editor is a type of program used for editing plain text files. Such programs are sometimes known as "notepad" software. Text editors are provided with operating systems and software development packages, and can be used to change configuration files, documentation files and programming language source code. Assembler A computer will not understand any program written in a language, other than its machine language. The programs written in other languages must be translated into the machine language. Such translation is performed with the help of software. A program which translates an assembly language program into a machine language program is called an assembler. Compiler It is a program which translates a high level language program into a machine language program. A compiler is more intelligent than an assembler. It checks all kinds of limits, ranges, errors etc. But its program run time is more and occupies a larger part of the memory. It has slow speed. Because a compiler goes through the entire program and then translates the entire program into machine codes. Interpreter An interpreter is a program which translates statements of a program into machine code. It translates only one statement of the program at a time. It reads only one statement of program, translates it and executes it. Then it reads the next statement of the program again translates it and executes it. In this way it proceeds further till all the statements are translated and executed. On the other hand, a compiler goes through the entire program and then translates the entire program into machine codes. A compiler is 5 to 25 times faster than an interpreter. By the compiler, the machine codes are saved permanently for future reference. On the other hand, the machine codes produced by interpreter are not saved. An interpreter is a small program as compared to compiler. It occupies less memory space, so it can be used in a smaller system which has limited memory space. Linker In high level languages, some built in header files or libraries are stored. These libraries are predefined and these contain basic functions which are essential for executing the program. These functions are linked to the libraries by a program called Linker. Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 13 Source File Compiler Object File Linker Library Executable program Figure: Compilation Process Algorithm In simple words an algorithm is a step-by-step procedure for solving a problem. Algorithms can be expressed in any language, from natural languages like English to programming languages like C. We use algorithms every day. Making algorithm is one of the principal challenges in programming language. An algorithm must always terminate after a finite number of steps. Important characteristics of algorithms are:      Finiteness Definiteness Language independent Input Output Flowchart Instead of directly converting the algorithm into program, an intermediate step called flowchart, is used before development of program. Hence, the pictorial representation of algorithm is called flowchart. Some of the symbols which are used in flowcharts are: Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 14 Start or Stop Connector Process Input or Output Decision Flow Figure: Flow chart symbols Examples of Algorithm and Flowchart 1) Write an algorithm and draw a flowchart to add two numbers just given by the user Answer: Algorithm Flowchart Step 1 : Start Start Step 2 : Declare variables a,b and sum Step 3 : Read values of a and b Declare Variables a,b and sum Read a and b Step 4 : Add a and b and assign the result to sum ; sum a+b Add a and b; sum a+b Step 5 : print sum Print Sum Step 6 : Stop End Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 15 2) Write an algorithm and draw a flowchart to find user input number is odd or even. Answer: Note: Odd and even number is calculated by dividing given number by 2. If remainder is zero then a number is even and if remainder is 1 then a number is odd. Algorithm Flowchart Step 1 : Start Start Step 2 : Declare variables num, rem Step 3 : Read num Declare Variables num and rem Read num Step 4 : Calculate remainder rem=num%2 Step 5 : if (rem==0) then print number is even and go to step 6 else print number is odd and go to step 6 Calculate rem=num%2 N Step 6 : Stop Is rem==0? Y Print Even Print Odd End 3) Develop an algorithm and draw flowchart for finding the sum of the first 100 natural numbers. Answer: Note: Here first 100 natural numbers are added. That means, sum=1+2+3+…. +100 Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 16 Algorithm Flowchart Step 1 : Start Start Step 2 : Declare variables i, and sum Declare Variables i and sum Step 3 : Initialize i=1 and sum=0 Step 4 : Repeat from step 4 to step 6 until i<=100 Initialize i=1 and sum=0 Step 5 : Calculate sum= sum + i Step 6 : Increment i by i=i+1 N Step 7 : Print sum Is i<=100 Y ? Step 8 : Stop Print sum Calculate sum=sum+i i+=i+1 End Pseudo Code Pseudo means not genuine or false or fake. Therefore, pseudo code means not a true program code, but is a code that gives some reflection of guide line for actual code. Pseudo code is false code only in the sense that it is not the programming language code that is used to direct the action of the computer. Pseudo code is a normal language construction modeled to look like statements available in many programming languages. Generally, pseudo code is the mixture of structured English and code. Structure English means writing mathematical procedures in English language using programming language structures (like IF, ELSE, DO, WHILE etc.). For example: IF coffee Then we drink coffee Else We drink Tea Good Luck Prepared By: Er. Krishna Prd. Neupane, MSc. in Computer Engineering & B.E. in Electronics and Communication Engineering Page 17