1 .2 Computer Basics
A computer is an electronic machine that stores, retrieves, and processes data. It cannot think or reason; it can only carry out instructions given to it. A set of instructions that directs its actions is called a program..Different programs are used to solve different problems. Ability to accept, store and execute programs makes the computer an invaluable and all-purpose business tool.
The first step of solving a problem by a computer is to develop a computer program and then store it in the memory. The computer then executes the instructions in the program.The instructions generally direct the computer to perform three basic functions over and over again; these are input, processing, and output. Collectively, these functions constitute the data processing cycle.
Input: Input devices feed the computer facts or data to be processe
Processing: The control and storing of data, numerical comparisons and arithmetic
operations are performed on the .input data to produce the results.
Output: The computer feeds the processed data or information to the output devices.
Keyboard System Monitor
(Input Umt) Unit (Output Unit)
I
(a)
Input Processing Output
Figure 1.1: a) Solving a problem with a computer, b) equivalent block diagram.
A computer reads a program and stores it in the memory and executes instructions to:
• Input data from disk, keyboard, or other storage media,
• Process data and
• Output results to display screen, disk or other media.
1.3 Components of a Computer Syste
A computer is used to process data and a data processing system consists of more than just machines. A computer system must contain:
• Hardware
• Software
• Humanware, and
• Operational procedures.
Hardware
Hardware refers to machines or physical equipment that 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 stored programs and input.devices for data,and it must make decisions, arithmetically manipulate data, and output results in the correct sequence. Programs are referred to as software. Software is generally categorized as:
• System software, and
• Application software.
System software consists of programs that help the use of a computer. These programs perform such standard tasks as organizing and maintaining 'data files, translating programs written in programming 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 syste.ms software the most important one is known as the operating system.
Application software includes programs to perform user applications. A c.omputer program for 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.
Humanware
Humanware refers to the persons who design, program, and operate a computer. There are numerous categories of jobs, but.the three principal positions for a large computer installation are: systems analyst, programmer, and computer operator. People in each of these areas generally perform special-purpose tasks under the supervision of a director or manager.
A systems analyst requires a broad background and extensive understanding of the above-three job .categories. The main task of a systems analyst is to study information systems and their processing requirements A systems analyst defines the applications problem, determines systems specifications, recommends hardware and software-and designs information-processing procedures.
A programmer requires a comprehensive knowledge of programming languages and standard coding procedures. This position does not require the.broader understanding of the structure and inner workings of an application. A programmer's principal.job is to code or prepare programs based on the specifications made by the systems analyst.
A computer operator requires the least extensive background of the three categories. A computer operator generally performs a series of well-defined tasks.to keep the computer operating at maximum efficiency. The efficiency of a computer installation depends on the ualitv and abilitv of the operational staff.
Operational Procedures
Operations of a data processing center require an extensive and clearly defined set ofprocedures for performing the essential functions. These functions generally include obtaining, preparing, and entering data into the computer, processing jobs, initiating new programs and changing.or deleting old ones etc. Such procedures require actions to be taken in the event of hardware or software malfunctions.
