Chemistry Second Paper book. pdf

1.3 Components of a Computer System 

A computer is used to process data and a data processing system must consist of more than just machines. A computer system must contain: hardware, software, humanware and operational procedures. 

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Hardware 
Hardware generally refers to the machine or physical equipment t hat performs the basic functions of the data processing cycle. In addition to the computer itself, other hardware devices are also required. These devices may be off-line that is detached from the computer and operating independently or they may be on-line that is directly connected to and controlled by the computer. A printer is an off-line device and a keyboard is an on-line device.

Software 

A program is a sequence of instructions which directs a computer to perform certain functions. A computer must have access to prewritten, stored programs to input and store data, make decisions, arithmetically manipulate and output data in the correct sequence. Programs are referred to as software. Computer system must be supported by extensive software systems. Software is generally categorized as either system software or application software. System software consists of programs that facilitate the use of computer by a user. These programs are sometimes referred to as utility programs. They perform such standard tasks as organizing and maintaining data files, translating programs written in various languages to a language acceptable to the computer, scheduling jobs through the computer, as well as aiding in other areas of general operations. Of all the systems software supplied by the manufacturer of a computer, the most important one is known as the operating system. Application software consists of programs to perform specific user applications. A computer program giving instructions for the steps involved in preparing results of a public examination is an example of applications software. Application programs are either purchased or written by the computer users for specific applications.