C – Commonly; O – Oriented; M – Machine; P – Particularly; U – Used; T – for Trade; E – Education; R – and Research.
In this age of computers there is no such activity that cannot be achieved without computers. Computer has become an indispensable and multipurpose tool. We are breathing in the computer age and gradually computer has become such a desire necessity of life that it is difficult to imagine life without it. This book will help you to gain an understanding of the basic as well as advanced concepts of computers. It will cover a foundational study of the computer hardware, software, operating systems, peripherals, the hardware maintenance etc.
Concept of Computer System
A computer is an advanced electronic device that takes raw data as input from the user and processes this data under the control of set of instructions (called program) and gives the result (output) and saves output for the future reference and usage.
To know about the working of a computer, first need to understand various terms such as Data, Processing and Information. First of all, lets start with three basic terms:-
- Data : Data is a collection of basic facts and figure without any sequence. This data is also called as raw data. When the data is collected as facts and figures, there is no meaning to it, at that time, for example, name of people, names of employees etc.
- Processing : Processing is the set of instructions given by the user to the related data that was collected earlier to output meaningful information. The computer does the required processing by making the necessary calculations, comparisons and decisions.
- Information : Information is the end point or the final output of any processed work. This meaningful output data is called information.
Characterstics of Computer
The major characteristics of computers are the following:
• Speed : A powerful computer is capable of executing about 3 million calculations per second.
• Accuracy : A computer’s accuracy is consistently high; if there are errors, they are due to errors in instructions given by the programmer.
• Reliability : The output generated by the computer is very reliable as long as the data is reliable.
• Memory/Storage Capacity : The computer can store large volumes of data and makes the retrieval of data an easy task.
• Versatility: The computer can accomplish many different things. It can accept information through various input-output devices, perform arithmetic and logic operations, generate a variety of outputs in a variety
of forms, etc.
• Automation: Once the instructions are fed into computer it works automatically without any human intervention.
• Diligence : A computer will never fail to perform its task due to distraction or laziness.
• Convenience : Computers are usually easy to access, and allow people to find information easily that without a would be very difficult.
• Flexibility : Computers can be used for entertainment, for business, by people who hold different ideals or who have varied goals. Almost anyone can use a computer, and computers can be used to assist with almost any goal.
Goals of Computers
- Problem-solving techniques using the computer.
- Analysis of complex problems and the synthesis of solutions .
- Comprehension of modern software engineering principles.
- A vast breadth and depth of knowledge in the discipline of computer science.
Like all machines, a computer needs to be directed and controlled in order to perform a task successfully. Until such time as a program is prepared and stored in the computer’s memory, the computer ‘knows’ absolutely nothing, not even how to accept or reject data. Even the most sophisticated computer, no matter how capable it is, must be told what to do. Until the capabilities and the limitations of a computer are recognized, its
usefulness cannot be thoroughly understood.
In the first place, it should be recognized that computers are capable of doing repetitive operations. A computer can perform similar operations thousands of times, without becoming bored, tired, or even careless.
Secondly, computers can process information at extremely rapid rates. For example, modern computers can solve certain classes of arithmetic problems millions of times faster than a skilled mathematician. Speeds
for performing decision-making operations are comparable to those for arithmetic operations but input-output operations, however, involve mechanical motion and hence require more time. On a typical computer system, cards are read at an average speed of 1000 cards per minute and as many as 1000 lines can be printed at the same rate.
Thirdly, computers may be programmed to calculate answers to whatever level of accuracy is specified by the programmer. In spite of newspaper headlines such as ‘Computer Fails’, these machines are very accurate
and reliable especially when the number of operations they can perform every second is considered. Because they are man-made machines, they sometimes malfunction or break down and have to be repaired. However,
in most instances when the computer fails, it is due to human error and is not the fault of the computer at all.
In the fourth place, general-purpose computers can be programmed to solve various types of problems because of their flexibility. One of the most important reasons why computers are so widely use today is that almost every big problem can be solved by solving a number of little problems-one after another. Finally, a computer, unlike a human being, has no intuition. A person may suddenly find the answer to a problem without working out too many of the details, but a computer can only proceed as it has been
History of the Development of Computers
In beginning, there were no computers. To add or subtract , man used his fingers and toes. Abacus is known to be the first mechanical calculating device. The main purpose of abacus was that additions and subtraction
coud be performed quickly. Abacus was developed by the Egyptians in the 10th centuary B.C, but the final structure was given in the 12th centuary A.D. by the Chinese educationists. Abacus is made up of a frame in which rods are fitted across with rounds beads sliding on the rod.
Napier’s Bones in an Abacus invented by John Napier.Napier’s used the bone rods for counting purpose where numbers were printed on them. With the help of these rods , one could do addition, subtraction, multiplication and division speedily.
Pascal’s calculator called ‘Pascaline’
In the year 1642, Blaise Pascal a French scientist invented an adding machine called Pascal’s calculator, which represents the position of digit with the help of gears in it. Though these machines were early forerunners to computer engineering, the calculator failed to be a great commercial success.
Leibniz was successfully introduced as a calculator onto the market in the year 1646. It was designed further in 1673 but it took until 1694 to complete. The calculator could perform the basic mathematical operations such as add, subtract, multiply, and divide. Wheels were placed at right angles which could be displaced by a special stepping mechanism.
Analytical Engine “The first Computer”
This analytical engine, the first fully-automatic calculating machine, was constructed by British computing pioneer Charles Babbage (1791-1871), who first conceived the idea of an advanced calculating machine to calculate and print mathematical tables in 1812. This Analytical Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete.
Five Generations of Computers
First Generation of Computers (1942-1955)
The beginning of commercial computer age is from UNIVAC (Universal Automatic Computer). The first generation computers were used during 1942-1955. They were based on vacuum tubes. Examples of first
generation computers are ENIVAC and UNIVAC-1.
• Vacuum tubes were the only electronic component available during those days.
• Vacuum tube technology made possible to make electronic digital computers.
• These computers could calculate data in millisecond.
• The computers were very large in size.
• They consumed a large amount of energy.
• Limited commercial use.
• Very slow speed.
• Used machine language only.
• Used magnetic drums which provide very less data storage.
Second Generation Computers (1955-1964)
The second generation computers used transistors. The size of the computers was decreased by replacing
vacuum tubes with transistors. The examples of second generation computers are IBM 7094 series, IBM
1400 series and CDC 164 etc.
• Smaller in size as compared to the first generation computers.
• Used less energy and were not heated.
• Better speed and could calculate data in microseconds
• Used faster peripherals like tape drives, magnetic disks, printer etc.
• Used Assembly language instead of Machine language.
• Cooling system was required
• Constant maintenance was required
• Only used for specific purposes
• Costly and not versatile
Third Generation Computers (1964-1975)
The Third generation computers used the integrated circuits (IC). The first IC was invented and used in 1961. The size of an IC is about ¼ square inch. A single IC chip may contain thousands of transistors. The computer became smaller in size, faster, more reliable and less expensive. The examples of third generation computers are IBM 370, IBM System/360, UNIVAC 1108 and UNIVAC AC 9000 etc.
An integrated circuit (IC), sometimes called a chip or microchip, is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, and transistors are fabricated.
• Smaller in size as compared to previous generations.
• More reliable.
• Used less energy.
• Better speed and could calculate data in nanoseconds.
• Air conditioning was required.
• Highly sophisticated technology required for the manufacturing of IC chips.
Fourth Generation Computers (1975-Present)
The fourth generation computers started with the invention of Microprocessor. The Microprocessor contains thousands of ICs. The LSI (Large Scale Integration) circuit and VLSI (Very Large Scale Integration) circuit was designed. It greatly reduced the size of computer. The size of modern Microprocessors is usually one square inch. It can contain millions of electronic circuits. The examples of fourth generation computers are
Apple Macintosh & IBM PC.
• More powerful and reliable than previous generations.
• Small in size
• Fast processing power with less power consumption
• Fan for heat discharging and thus to keep cold.
• Cheapest among all generations
• All types of High level languages can be used in this type of computers
• The latest technology is required for manufacturing of Microprocessors.
Fifth Generation Computers (Present & Beyond)
Scientists are working hard on the 5th generation computers with quite a few breakthroughs. It is based on the technique of Artificial Intelligence (AI). Computers can understand spoken words & imitate human reasoning. IBM Watson computer is one example that outsmarts Harvard University Students.