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 Generally, Computer hardware is divided into four main functional areas. These are:  Input devices Input devices  Output devices Output devices  Central Processing Unit (CPU) Central Processing Unit (CPU)  Memory Memory

 Input Devices: Allows getting data into the computer. A simple example of input device is keyboard.  Output devices: Shows the result after processing data or information.

 Central Processing Unit (CPU): It is electronic circuit that manipulates data into the required information; It consists of two parts: Arithmetic Logic Unit (ALU) and Control Unit (CU).  Arithmetic Logic Unit It the “Brain” of the computer system, i.e., performs the most important operation of the computer system – arithmetic and logic operation on the data.  Control Unit Directs and coordinates the execution of stored program instruction.

 Memory: There are two kinds of computer memory: primary and secondary.  Primary memory is accessible directly by the processing unit. Random Access Memory (RAM) is an example of primary memory. As soon as the computer is switched off the contents of the primary memory is lost. You can store and retrieve data much faster with primary memory compared to secondary memory.  Secondary memory is used to store data permanently. An example of this type of memory includes floppy disks, magnetic disk. Primary memory is more expensive than secondary memory (because of this the size of primary memory is less than that of secondary memory).

 Computer is a dumb machine and it cannot do any work without instruction from the user; it requires specific logically related instructions that the developer feeds into a computer to solve a particular problem.  It can be acquire a program in two ways; packaged software and custom software. Package software is a readymade set of programs while custom software is a set of programs that a written according to the user’s requirements.

 It is a set of rules that provides a way of telling the computer what operations to perform.  A programming language, the key to communicating with the computer, has certain definite characteristics. It has a limited vocabulary. Each “word" in it has precise meaning. Even though a programming language has limitations, it can still be used in a step-by-step fashion to solve complex problems. There is not, however, just one programming language; there are many. Ex.:  COBOL, BASIC, FORTRAN, C, C++, and Pascal. All languages have a grammar of their own -known as syntax of the language.

 Before a program is written, a detail specification must be drawn up showing exactly what is to be done by the program. It is very important that a programmer should not start trying to write a computer program before a clear specification has been created. Usually, such as a specification is in three main parts:  Input: a description of the format of the input data.  Output: a description of the format of output data.  Processing: a description of the processes of the program must follow to get the output from the input.

 When preparing problem solutions for the computer, it is not enough just to know the rules of a computer language; developing a program requires five steps:  Defining the problem Defining the problem  Planning the solution Planning the solution  Coding the Program Coding the Program  Testing the Program Testing the Program  Documentation Documentation

 Defining the Problem: Analyzing system requirements, i.e., kind of input, processing, and output required.  Planning the solution: To solve programming problem, one must follow a methodical approach, i.e., design an ordered set if activities that will convert a given input into the desired an algorithm for the problem; an algorithm consists of three main components ( these are input, process and output). algorithm

 Algorithm is a step-by-step procedure to solve a given problem  Algorithms implemented by a computer are known as computer programs.  A program consists of basically the following operations:  Sequence in order  Selection - Choosing from set (e.g., if…else)  Iteration – Repetition These three operations are sufficient to describe any algorithm.  In the problem-solving phase of computer programming, you will be designing algorithms. This means that you will have to be conscious of the strategies you use to solve problems in order to apply them to programming problems. These algorithms can be designed though the use of flowcharts or pseudocode.

 Coding the Program: We need a language to express an algorithm. A computer algorithm requires a computer language. There are many high-level languages, each with a different compiler, such as FORTRAN, COBOL, C, C++, Pascal, ADA, ALGOL, BASIC, etc.  Testing the Program: Once the program code is written, it is very unlikely that it will be perfect on the first run. Programming errors are common in the early versions of the program.

 Documenting the Program: Documenting the program is a detailed description of the programming cycle and specific facts about the program. Documenting is an on-going process needed to supplement human memory and help organize program planning. Documentation is also critical to communication with other who might have an interest in your program

A procedure is a finite sequence of well-defined instructions, each of which can be mechanically carried out in a finite amount of time. Flowcharting is a tool developed in the computer industry, for showing the steps involved in a process. A flowchart is a diagram made up of boxes, diamonds and other shapes, connected by arrows - each shape represents a step in the process, and the arrows show the order in which they occur. Flowcharting combines symbols and flowlines, to show figuratively the operation of an algorithm.

Flowcharting Symbols: There are 6 basic symbols commonly used in flowcharting of assembly language programs: Terminal, Process, input/output, Decision, Connector and Predefined Process. Flowcharting Symbols