Chapter 1 : Overview of Computer and Programming By Suraya Alias

 Computer A machine that can receive, store, transform, and output data of all kinds  Microproccesor / Central Processing Unit (CPU) A silicon chip containing the circuitry for a computer processor Coordinates all computer operations and perform arithmetic and logical expression on data  Hardware The actual component equipment such as mouse, monitor, keyboard. Is tangible.  Software Set of programs associated with a computer Programs – list of instructions that enables computer to perform specific task Is Intangible or not tangible 1-2

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 Memory Refers to data storage such as Random Access Memory (RAM) and Read Only Memory (ROM)  Memory cell an individual storage location in a memory  Address memory the position of the memory cell in the main memory  RAM Volatile memory (need power to access it), the part of the main memory that temporarily stores programs, data and results  ROM Non-volatile memory, the part of memory that permanently stores program and data such as system date and time in your pc or BIOS settings 1-5

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1-8 Bit – Binary digit of 0 and 1 Byte  the amount of storage required to store a single character  1 byte = 8 bits  1Kilobyte = 1024 byte  1Megabyte = 1024 KB  1Gigabye = 1024 MB

1-9 Data storage To retrieve data and to store data from the main memory Secondary Storage Units such as hard disk, flash drive that retain data even the power is off Register high speed memory location inside the CPU

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 Local Area Network (LAN) Computer, printers, scanners devices connected by cables for intercommunication  Metropolition Area Network (MAN) is a large computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks and the Internet  Wide Area Network (WAN) A network such as the Internet that connects computers and LANs over the world ***Discuss the differences between Internet, Intranet and Extranet

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 System Software Operating System (OS), such as Windows Vista, MAC or Linux Software that controls interaction between user and the computer, and all the resources  Application software Used for specific task such as Microsoft Word, Adobe photoshop 1- 14

 Machine language Binary number codes understood by a specific CPU (is not standardized)  Assembly Language Mnemonic codes that correspond to machine language notification  High Level Language Machine-independent programming language that combines algebraic expression and English symbols such as C and C++. Such as x = x + y; Means that add the value of variable x and y, and store the results in variable x by replacing the previous value.  Compiler Software that translates a high-level language program into machine language 1- 15

 Source File File that contains program written in a high level language, the input for a compiler Created by the programmer using editor or word processor such as ‘helloworld.c’ The C compiler will scan the source file, checks the programs if it follows the syntax  Syntax Grammar rules of a programming language If ‘helloworld.c’ is correct, the compiler saves it in an object file such as “helloworld.o” using binary file format  Linker program Software that combines object files and resolves cross- reference to create an executable machine language program such as “helloworld.exe” that can be run using a loader  IDE (Integrated Development Environment) High level compiler that are sold/distributed as a package that combines an editor, compiler, linker and loader. Such as Visual C++, codeblocks 1- 16

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1- 18 Executing a program Input -> Process -> Output

 1) Specify the problem requirement  2) Analyze the problem  3) Design Algorithm to solve the problem  4) Implement the Algorithm  5) Test and verify the completed program  6) Maintain and update the program 1- 19

 Example  1) Problem Requirement State the problem clearly and what is required Compute and display the total cost of apples given the number of pounds of apples purchased and the cost per pounds of apples  2)Analysis Identifies the input, output or any additional requirement or constraint on the solution Problem Input  Quantity of apples purchased (in pounds)  Cost per pound of apples (in dollars per pound) Problem Output  Total cost of apples (in dollars) Formula  Total cost of apple = Cost per pound * pounds of apples

 Abstraction  The process of modeling a problem by extracting the essential variables and their relationship  Algorithm A list of steps for solving a problem  Top-down Design (divide and conquer) Breaking a problem into its major sub problems and then solving the sub problems  3) Design Designing the algorithm to solve the problem requires you to develop a list of steps called an algorithm. Use the top-down design method Algorithm for programming problem  1) get the data  2) perform computation  3) display the results

Stepwise refinement  Development of a detailed list of steps to solve a particular step in the original algorithm Desk checking  The step by step simulation of the computer execution of an algorithm  4) Implementation Implementing the algorithm involves writing it as program using programming language such C or C++  5) Testing Testing and verifying the program requires testing the completed program to verify that it works as desired  6) Maintenance Maintaining and updating the program involves modifying a program to remove previous errors and change of requirement 1- 22

 Case study Converting Miles to Kilometers  1) Problem Definition / Requirement Write a program to convert distance from miles to kilometers  2) Analysis What are the data requirement and formula needed? Problem Input  miles /*distance in miles*/ Problem Output  kms /*distance in kilometers*/ Relevant formula  1 mile = kilometers 1- 23

 3) Design Algorithm  1) Get the distance in miles  2) Convert the distance to kilometers  3) Display the distance in kilometers Step 2 needs refinement  1) Get the distance in miles  2) Convert the distance to kilometers  2.1) The distance in kilometers is times the distance in miles  3) Display the distance in kilometers 1- 24

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