Cos1 PDF

INTRODUCTIONComputer: A computer is basically defined as a tool or machine used for processing data to give required information. It is capable of:taking input data through the keyboard (input unit),storing the input data in a diskette, hard disk or other medium,processing it in the central processi...

INTRODUCTIONComputer: A computer is basically defined as a tool or machine used for processing data to give required information. It is capable of:taking input data through the keyboard (input unit),storing the input data in a diskette, hard disk or other medium,processing it in the central processing unit (CPU) andgiving out the result (output) on the screen or the Visual Display Unit (VDU).(DATA) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (INFORMATION)A schematic diagram to define a computerData: The term data refers to facts about a person, object or place, e.g. name, age, complexion, school, class, height etc.Information: This is referred to as processed data or a meaningful statement, e.g. net pay of workers, examination results of students, list of successful candidates in an examination or interview etc.Methods of Data ProcessingThe following are the three methods that have been widely used for data processing over the years:The Manual method,The Mechanical method andThe Computer method.The Manual MethodThe manual method of data processing involves the use of chalk, wall, pen, pencil and the like. These devices, machines or tools facilitate human efforts in recording, classifying, manipulating, sorting and presenting data or information. The manual data processing operations entail considerable manual efforts. Thus, the manual method is cumbersome, tiresome, boring, frustrating and time consuming. Furthermore, the processing of data by the manual method is likely to be affected by human errors. When there are errors, then the reliability, accuracy, neatness, tidiness, and validity would be in doubt. The manual method does not allow for the processing of large volumes of data on a regular and timely basis.The Mechanical MethodThe mechanical method of data processing involves the use of machines such as the typewriter, adding machines and the like. These machines facilitate human efforts in recording, classifying, manipulating, sorting and presenting data or information. The mechanical operations are basically routine in nature. There is virtually no creative thinking. Mechanical operations are noisy, hazardous, error prone and untidy. The mechanical method does not allow for the processing of large volumes of data continuously and timely.The Computer MethodThe computer method of carrying out data processing has the following major features:Data can be steadily and continuously processedThe operations are practically not noisyThere is a store where data and instructions can be stored temporarily and permanent.Errors can be easily and neatly corrected.Output reports are usually very neat, decent and can be produced in various forms such as adding graphs, diagrams and pictures etc.Accuracy and reliability are highly enhancedCharacteristics of a ComputerSpeed: The computer can manipulate large data at incredible speed and response time can be very fast.Accuracy: Its accuracy is very high and its consistency can be relied upon. Errors committed in computing are mostly due to human rather than technological weakness. There are in-built error detecting schemes in the computer.Storage: It has both internal and external storage facilities for holding data and instructions. This capacity varies from one machine to the other. Memories are built up in K (Kilo) modules where K=1024 memory locations.Automatic: Once a program is in the computer’s memory, it can run automatically each time it is opened. The individual has little or no instruction to give again.Reliability: Being a machine, a computer does not suffer human traits of tiredness and lack of concentration. It will perform the last job with the same speed and accuracy as the first job every time even if ten million jobs are involved.Flexibility: It can perform any type of task once it can be reduced to logical steps. Modern computers can be used to perform a variety of functions like on-line processing, multiprogramming, real time processing etc.The Computing SystemThe computing system is made up of the computer system, the user and the environment in which the computer is operated.The Computer SystemThe computer system is made up of the hardware and the software.The HardwareThe computer hardware comprises the input unit, the processing unit and the output unit.The input unit comprises those media through which data is fed into the computer. Examples include the keyboard, mouse, joystick, trackball and scanner.The processing unit is made up of the Arithmetic and Logic Unit (ALU), the control unit and the main memory. The main memory also known as the primary memory is made up of the Read Only Memory (ROM); is non-volatile memory that permanently stores instructions for your computer, and the Random Access Memory (RAM); is volatile memory that temporarily stores the files you are working on.The output unit is made up of those media through which data, instructions for processing the data (program), and the result of the processing operation are displayed for the user to see. Examples of the output unit are the monitor (Visual Display Unit), scanners, speakers and the printer.The SoftwareComputer software is the series of instructions that enable the computer to perform a task or group of tasks. A program is made up of a group of instructions to perform a task. Series of programs linked together make up software. Computer programs could be categorized into system software, utility software, and application programs.The Computer UsersComputer users are the different categories of personnel that operate the computer. We have expert users, casual users and basic users. The expert users are users with advanced knowledge about computers software and hardware that require no assistance when working with the computer. They are computer engineers, computer programmers etc.The casual users are users who have some computer experience and can navigate and use the computer without much assistance.The basic users are users who just started using the computer and need a lot of assistance.The Computing EnvironmentThe computing environment includes the building housing the other elements of the computing system namely the computer and the users, the furniture, auxiliary devices such as the voltage stabilizer, the Uninterruptible Power Supply System (UPS), the fans, the air conditioners etc.A Brief History of Computer TechnologyA complete history of computing would include a multitude of diverse devices such as the ancient Chinese abacus, the Jacquard loom (1805) and Charles Babbage’s “analytical engine” (1834). It would also include a discussion of mechanical, analog and digital computing architectures. As late as the 1960s, mechanical devices, such as the Marchant calculator, still found widespread application in science and engineering. During the early days of electronic computing devices, there was much discussion about the relative merits of analog vs. digital computers. In fact, as late as the 1960s, analog computers were routinely used to solve systems of finite difference equations arising in oil reservoir modeling. In the end, digital computing devices proved to have the power, economics and scalability necessary to deal with large scale computations. Digital computers now dominate the computing world in all areas ranging from the hand calculator to the supercomputer and are pervasive throughout society. Therefore, this brief sketch of the development of scientific computing is limited to the area of digital, electronic computers.