1.2 Computer systems  (Page 5/8)

Mouse: - Mouse is an input device that is used with your personal computer. It rolls on a small ball and has two or three buttons on the top.When you roll the mouse across a flat surface the screen censors the mouse in the direction of mouse movement. The cursor moves very fast with mouse giving you more freedom to work in any direction. It is easier and faster to move through a mouse.

Scanner: The keyboard can input only text through keys provided in it. If we want to input a picture the keyboard cannot do that. Scanner is an optical device that can input any graphical matter and display it back.

Output Devices

Monitor: The most popular input/output device is the monitor. A Keyboard is used to input data and Monitor is used to display the input data and to receive massages from the computer. A monitor has its own box which is separated from the main computer system and is connected to the computer by cable. It can be color or monochrome. It is controlled by an output device called a graphics card. Displayable area measured in dots per inch, dots are often referred to as pixels. Standard resolution is 640 by 480. Many cards support resolution of 1280 by 1024 or better. Number of colors supported varies from 16 to billions

Printer: It is an important output device which can be used to get a printed copy of the processed text or result on paper. There are different types of printers that are designed for different types of applications.

Buses

Bus is a subsystem that transfers data or power between computer components inside a computer or between computers. Bus can logically connect several peripherals over the same set of wires. Each bus defines its set of connectors to physically plug devices, cards or cables together. The buses are categorized depending on their tasks:

• The data bus transfers actual data.
• The address bus transfers information about where the data should go.
• The control bus carries signals that report the status of various devices.

Computer software

Data and algorithms

There are many steps involved in writing a computer program to solve a given problem. The steps go form problem formulation and specification, to design of the solution, to implementation, testing and documentation, and evaluation the solution.

Once we have a suitable mathematical model for our problem, we attempt to find a solution in term of that model. Our initial goal is to find a solution in the form of an algorithm. So what is an algorithm?

Algorithm is a finite sequence of instructions each of which has a clear meaning and can be performed with a finite amount of effort in a finite length of time.

How do you represent an algorithm? The most obvious representation: source code of a programming language. However, writing source code before you fully understand an algorithm often leads to difficult-to-find bugs. So, algorithms may be presented ...

1. In words

To present the algorithm in words we may describe the tasks step by step.

2.As a flowchart

A familiar technique for overcoming those bugs involves flowcharts.