IMPORTANT NOTES OF COMPUTER FOR IBPS PO CLERK
INTRODUCTION TO COMPUTERS
Computer Awareness is one of the Important topic related to IBPS Banking Exams.Through this blog I will be updating Important notes related to Computer knowledge.In this post I have discussed Basics about computers.Hope this will be helpful for you....
1.1 Introduction
The present century has seen a revolution in Information Technology all over the world. Computers are playing an increasingly vital role, touching upon every aspect of our day today life. Information processing has become a major social activity. More than 70% of a typical executive's time is spent in processing some type of information.
A computer is an electronic device designed to perform arithmetic operation. It can also perform several non arithmetic operations on the alphabetic or numeric data used. These operations are performed at very high speeds with a high level of accuracy.
1.2 Characteristics of Computers
Some of the important characteristics of computer systems, which make computer based processing very useful in its practical applications, are described here.
Volume
Large volumes of data can be stored and processed by a computer system with a high degree of efficiency. The use of computers has thus made the processing of information economical by reducing unnecessary paper work.
Speed
A computer can process large volumes of data at very high speeds. The time required to execute a basic operation in a computer system varies between a few microseconds, nanoseconds or Pico seconds. With the advances in electronic technology, the processing speeds are increasing even further.
Accuracy
Coupled with the capacity to handle large volumes of data at high speeds, is the fact that the computer is extremely accurate. A human being commits approximately one error for every 500 1000 calculations using a calculator, while processing done by a computer is completely error free. The calculation can be repeated any number of times without worrying about errors. The accuracy of the computer output is wholly directly dependent on the accuracy of the input data and the correctness of the program, i.e., the set of instructions given by the user to process the data. The phrase garbage in garbage out (GIGO) is generally used to describe inaccurate output caused by incorrect input data. This implies that errors seemingly caused by computers are in fact caused by incorrect input of data or incorrect programs, and are not errors incurred during the processing.
Complexity
In the past, computations with complex algorithms could not be done, as a single process, if done manually, was time consuming and also had a high probability of errors. Mathematical optimisation using operation research techniques like linear programming, simulation, etc., have been successfully used in modelling real life applications only because of computers.
Quick/Easy Access
Information, by definition, is of no relevance if it cannot be made available at the right time. Computers, with their inherent characteristics of fast processing, have made it possible to retrieve and analyse data within a stipulated time. This has improved the timely availability of information.
Diligence
Unlike a human being, a computer does not suffer from fatigue, boredom, or lack of concentration while performing repetitive tasks. If a billion calculations are given to the computer, the billionth calculation will be as accurate as the first. Thus, for work that is repetitive in nature and where consistency needs to be maintained, computers have proved to be highly economical.
To summarize, the computer is a versatile, diligent machine that operates on a set of instructions and is capable of handling large volumes of data at tremendous speeds with a high degree of accuracy, ensuring timely, accurate and easy to access information.
1.2 A Brief History of Computer
In 1833, Charles Babbage began his work on the Analytical Machine. It was this machine which proved to be the prototype of the modern computer. The requirements for precision engineering were found impossible to achieve at the time and Babbage was unable to produce a working model. But this concept opened up avenues of the future development of computers.
1.2.1 Stages in the Evolution of the Computer
It has been more than 3000 years, from the days of the early computing machines to the existing generation of computers. The first stage in this evolution was the Abacus, a mechanical device; this followed by punched cards and finally came the revolution in computers and microprocessors. The impact of the evolution has been tremendous. A brief description of the various stages in the evolutionary process is given below:
1.2.1.1 Abacus
The Abacus was the first mechanical device developed approximately 3000 years ago to help process data. It consisted of a frame in which beads could slide on wires. The wires were arranged in columns. The column on the extreme right was for units, the one to its left for tens and so on. Pushing the appropriate beads could represent various numbers. This device could perform simple addition and subtraction operations.
1.2.1.2 Punched Card
The history of the punched card dates back to about the end of the American Revolution. At that time a French weaver, Joseph Marie Jacquard, used punched cards to control looms. The Jacquard card is a card with punched holes to guide the warp threads on a loom. It was used primarily to automate weaving patterns into the fabric. It was this concept that gave Dr. Herman Hollerith the idea to build the census machine. i.e., a machine into which data was fed by means of card which had information punched on them. He devised a coding scheme, which could be sued to punch data on cards. This machine was first used to tabulate census data in 1980. Hollerith later formed the Tabulating Machine Company to sell his invention. it is this company which later merged with others to form what is today the world's largest computer manufacturing company, the International Business Machines Corporation (IBM).
1.2.1.3 Analytical Engine
In 1833, Charles Babbage, a professor of mathematics at Cambridge University developed the concept for an analytical engine which could perform arithmetic functions on data, which was read in from punched cards. Babbage's requirements of precision engineering were impossible to achieve at that time and therefore a working model could not be produced.
Mark 1
In 1944, Howard Eiken, a Harvard professor, built an automatic calculating machine called the Mark 1 digital computer. It was an electromechanical device consisting of telephone relays and rotating mechanical wheels. It was controlled by a sequence of instructions punched into a roll of paper tape. In many ways, Mark 1 was a realization of Babbage's dream.
Eniac
While Mark 1 was the first electromechanical computer, the first electronic general purpose computer, called ENIAC (Electronic Numerical Integrator and Calculator), was built in 1946 by a team of professors at More School, University of Pennsylvania. As many as 18,000 vacuum tubes were used in building this machine. It weighed about 30 tons, occupied 1500 sq. ft of space and had a small memory (as compared to the memory capabilities of today's computers) of about 20 accumulators. It could perform 300 multiplication per second, making it 300 times faster than any other machine of that era.
Univac
The world's first commercial data processing machine UNIVAC (Universal Automatic Computer) was installed at the U.S. Bureau of Census in 1951. John Von Neumann had developed the concept of an “internally stored program", which was used in designing the UNIVAC system. By 1963, just 12 years after its installation, it retired as a historic relic.
1.3 Computer Generations
Computers are often grouped into categories known as computer generations. A brief description of the various generations of computers and their predominant features is given below:
1.3.1 First Generation (1946 -1954)
These computers used vacuum tubes as the main electronic element and magnetic drums as the main memory. Programming had to be done in machine/assembly language only. These computers were physically large, generated significant heat and the speed of operations was in terms of milliseconds (i.e., thousandth of a second).
1.3.2 Second Generation (1955- 1964)
In the second generation computers, transistors replaced vacuum tubes as the basic electronic element. These transistorised computers were faster, more compact and reliable. The speed of operations was in terms of microseconds (i.e., millionth of a second). The magnetic core was introduced as the main memory. Magnetic tapes and disks were used for storage of bulk data. In the area of software, compilers were introduced thereby enabling the programmers to write programs in high level languages. Some examples of such computers are: IBM 1401, Honeywell 800, IBM 1620.
1.3.3 Third Generation (1965- 1974)
The introduction of the IBM 360 series of computers in 1965 marked the beginning of this generation. Transistors were replaced by monolithic integrated circuits. This reduced the size further and improved upon the speed, although the speed of computation was still in terms of microseconds. In terms of software, it was in this generation that operating systems were introduced.
1.3.4 Fourth Generation (1975 onwards)
In this generation of computers, significant developments emerged, both in hardware and software. Semiconductor memory replaced the core memory, which enable the achievement of higher speeds at a lower cost. The introduction of micro programmed logic permitted the machine logic to be altered to suit the user's needs. The facility of operating systems with "virtual memory" enabled a programmer to write programs requiring greater memory space than actually available in the main memory. The processing speeds were of the order of nanoseconds.
1.3.5 Fifth Generation
This generation represents more technological developments both in hardware and software areas. Fifth generation computers are aimed specifically at Artificial Intelligence (AI) applications.
1.4 Classification of Computers
Computers are divided into two categories on the basis of the type of data they are designed to process. Data may be obtained either as a result of counting, in which case it is called discrete data, or by using some continuous signal measuring instruments, in which case it is called continuous data.
The classification of computers, based on the type of data, is as follows:
1.4.1 Digital Computers
These computers operate on discrete data and are commonly used in business applications. Digital computers can be further classified into general purpose and special purpose computers.
1.4.2 General Purpose Computers
A general purpose computer is one that can be used for a variety of applications. Its versatility enables, execution of programs of almost any type. These are used for business applications.
1.4.3 Special Purpose Computers
These are designed to perform specific tasks. Such computers lack versatility. However, they perform the task for which they are designed very efficiently. Aircraft control systems and missile guidance systems are some examples of special purpose computers.
1.4.4 Analog Computers
This type of computer works on continuous data measured along a continuous scale. For example, a speedometer is a mechanical device that works on continuous data. Analog computers are commonly used in process control systems, which monitor pressure, temperature, flow etc.
1.4.5 Hybrid Computers
This type of computer combines the properties of both analog and digital computers. A typical example is found in medicine, where analog properties are used to record the patient's data, while digital properties help in the analysis of the data as well as in monitoring the patient’s health. Computers are also classified on the basis of their physical size, memory and processing speeds. Five of these categories are described below:
Microcomputers
Low-Cost small digital computers are known as Microcomputers. Portable computers, personal computers, (PCs) (single user desk top computers), computers for dedicated applications such as industrial control, instrumentation, appliances control, etc. come under the category of Microcomputers. Microcomputers are system based on the use of microprocessors. A microprocessor is a programmable large scale integrated circuit chip containing all the elements required to process binary encoded data. In simpler terms, a microcomputer performs all arithmetic and logical functions of a computer. Microcomputers are also called personal computers (PCs).
Minicomputers
These systems are more powerful than microcomputers and are also more expensive. The word length is generally 16 bits or more. The processing speed of a computer is often measured in terms of MIPS, i.e., millions of instructions per second. These computers have a processing power of the order of 1.5 MIPS. They are multi-user system.
Supermini Computers
Supermini computers are faster than minicomputers. The word length is generally 32 bits and the processing speed is more than 1.5 MIPS. These systems have efficient time sharing operating systems with multi programming features.
Mainframe Computers
Mainframes are very powerful large computers. They are rarely used and are being replaced by computer network (distributed computer system). These are machines with word lengths of 32 bits or more. The processing speed is of the order of 10 MIPS. These computers support a large main memory. In the time sharing mode, due to fast processing speeds, they can support hundreds of terminals. The number of processors in mainframe varies from one to six.
1.5. Computers Today
Today computers are classified as notebook computers (laptop computer), Personal Digital Assistant (PDA, also know as Palmtop computer), desktop computers (PCs). Work stations, Servers and Supercomputers.
1.5.1 Laptop or notebook computers
Laptop or notebook computers are personal portable computers. They are used for word processing and spreadsheet computing while a person is travelling. Their power supply is from batteries. They consume less power. They use hard disks, floppy disks and flat LCD (Liquid Crystal Display). They can be connected to computer network. Wireless connection can be provided to laptops so that they can get information from large stationary computers. Notebooks use 32–bit processor specially designed for such computers.
1.5.2 Desktop Computers
These are single-user PCs (Personal Computers). 32- bit processors like Pentium III, Celeron, PowerPC etc. They use hard disks of capacity 8 GB - 20 GB. RAM capacity is 16 or 32 MB. They use 3.5-inch floppy disks. They use MS-DOS or WIDOWS-98 operating system.
1.5.3 Workstations
Workstations are also desktop computers. They are more powerful than desktop machines. They are provided with graphics capability. They are used for numeric and graphic intensive applications. Their hard disk and RAM capacity is more than desktop computers. They use hard disks of about 20 GB to 75 GB and RAM 64 MB. They use RISC processors such as DEC’s Alpha processor, SUN’s SPARC processor, HP’s PA-RISC, etc. Operating systems used are UNIX, SUN’s Solaries HP’s HP-UX, etc.
Another definition of workstation is “ When a computer is connected to a network, it becomes a node on the network and is referred to as a workstation”. Diskless Workstations boot directly from the server using special boot routines on the network interface card.
1.5.4 Servers
Serves are power computers. A number of PCs and terminals are connected to a server through a communicating network. Server has large disk and RAM capacity. A low-end server contains one microprocessor whereas a high-end server may contain more than one microprocessor. Microprocessors within the computer operate in parallel. A person working on PC connected to server, makes simple computation on the PC. For more complex computation he can connect he can connect his PC to server through LAN. He can utilise computing power, facilities and database available with server. He can also use the facilities available at other PC connected to the server.
1.5.5 Supercomputers
Supercomputers are the fastest computers and can be used to solve a wide range of large-scale problems, which require extensive numeric computations like complex molecular structural analysis, weather forecasting, etc. The processing speeds are of the order of 100 MIPS. These machines have word lengths of 64 bits or more.
1.6 Basic Computer Concepts
A computer takes in data, processes it and gives out information. So when we speak of the parts of a computer, there should be parts to:
Put in data
Process this data and
Get the information out.
The computer parts therefore, have been named exactly according to the function they are supposed to do.
The word 'input' means something that the user of the computer will 'put in'. Similarly the word ‘output’ means something that the computer will 'put out' after doing some work or 'processing' on the data. The word 'device' simply means a 'thing' or a 'gadget' that helps to input and output.
