What is Computer?Parts of Computers?Classification of computers?
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What is Computer?Parts of Computers?Classification of computers?
A computer is an electronic machine that takes input from the user, processes the given input and generates output in the form of useful information. A computer accepts input in different forms such as data, programs and user reply. Data refer to the raw details that need to be processed to generate some useful information. Programs refer to the set of instructions that can be executed by the computer in sequential or non-sequential manner. User reply is the input provided by the user in response to a question asked by the computer. The main task of a computer system is to process the given input of any type in an efficient manner. Therefore, computer is also known by various other names such as data processing unit, data processor and data processing system.A computer includes various devices that function as an integrated system to perform several tasks described above. These devices are:
Central Processing Unit (CPU):It is the processor of the computer that is responsible for controlling and executing instructions in the computer. It is considered as the most significant component of the computer. It is the "brain" of the computer.
Monitor:
It is a screen, which displays information in visual form, after receiving the video signals from the computer.Keyboard and Mouse:
These are the devices, which are used by the computer, for receiving input from the user.
The unique capabilities and characteristics of a computer have made it very popular among its various users, including engineers. managers, accountants, teachers, students, etc. The characteristics and capabilities of a modern digital computer include, among others:
Speed :A computer is a fast electronic device that can solve large and complex problems in few seconds. The speed of n computer generally depends upon its hardware configuration.
Storage capacity: A computer can store huge amount of data in its different storage components in many different formats. The storage area of a computer system is generally divided into two categories, main memory and secondary storage.
Accuracy: A computer carries out calculations with great accuracy. The accuracy achieved by a computer depends upon its hardware configuration and the instructions.
Reliability: A computer produces results with no error. Most of the errors generated in the computer are human errors that are created by the user itself. Therefore, they are very trustworthy machines.
Versatility: Computers are versatile machines. They can perform many different tasks and can be used for many different purposes.
Diligence: Computers can perform repetitive calculations any number of times with the same accuracy.Computers do not suffer from human traits, such as tiredness, fatigue, lack of concentration, etc. Although computers are highly reliable and versatile machines, they do possess certain limitations. Since computers are capable of doing only what they are instructed to do, any wrong instruction (or faulty logic or any wrong data may result in erroneous output. This is popularly known as "Garbage-In, Garbage-Out (GIGO).
Computer is a dumb machine and therefore lacks "common sense". Anything it does is a result of huma instructions. It carries out instructions as long as it can understand them, no matter whether they are right or wrong.Although computers can be instructed to make certain decisions based on mathematical or logical equations, they cannot make decisions in situations where qualitative considerations are involved.
Classification of Computers :
There are different types of computers available these days. The function of each type of computer is to process the data and provide some output to the users. However, the methods or techniques used by these computers to process and handle the data may be different. We can classify the computers according to the following three criteria:1. Based on operating principles
2. Based on applications
3. Based on size and capability
★ Based on Operating Principles :
On the basis of operations performed and methods used to store and process the data and information,computers can be classified into the following categories:
.Analog computers
.Digital computers
.Hybrid computers
Analog computers : The analog computers represent data in the form of continuous electrical signals having a specific magnitude. These computers are very fast in their operation and allow several other operations to be carried out at the same time. However, the results produced by these computers are not very accurate. Therefore, the analog computers are widely used in applications in which the accuracy of results is not a major concern. They are powerful tools to solve differential equations. The electronic circuit employed in modern analog computers is generally an Operational Amplifier
(Op-Amp). It is made up of semiconductor integrated circuits. The three different characteristic features of Op-Amps are as follows:
★They have large voltage gain. The voltage gain of an amplifier is defined as the ratio of the output voltage to the input voltage.
★They have infinite input resistance. The input resistance is defined as the ratio of change in the input voltage to the change in input current. .
★They have zero output resistance.The output resistance is the nominal resistance measured with no load.
Digital computers:
The digital computer, also known as the digital information processing system, is a type of computer that stores and processes data in the digital form. Therefore, each type of data is usually stored in these computers in terms of Os and Is. The output produced by these computers is also in the digital form. The digital computers are also capable of processing the analog data. However, the analog data should be first converted to the digital form, before being processed by these computers. Similarly, if we want the output in the analog form, then the digital information produced by these computers should be first converted to an analog form. These conversions are generally carried out by the in-built components of digital computers.
Digital computers are generally faster and more reliable than the analog computer systems and provide more accurate results. The computer used by a home user is a typical example of digital computer. The digital computers are also employed in colleges, universities and small and medium sized businesses.
The different hardware components of a digital computer are an Arithmetic-Logic Unit (ALU), a Control Unit (CU), a memory unit and I/O units. The ALU of a digital computer is used to perform various arithmetic operations, such as addition, subtraction, multiplication and division and various logic operations such as AND, OR, NOT, etc. CU helps in directing the operations of ALU. The memory unit is used to store the data on temporary or permanent basis. The input units are used to enter the data into the computer and the output units is used to display the information generated by the computer to the user.
Hybrid computers:The hybrid computer is a combination of analog computer and digital computer because it encompasses the best features of both these computers. Therefore, the hardware components of hybrid computers are usually the mixture of analog and digital components. These features make the hybrid computers very fast, efficient and reliable. In these computers, data is generally measured and processed in the form of electrical signals and is stored with the help of digital components. However, these computers can also be used to perform various types of logical operations.The input accepted by the hybrid computers is a continuously varying input signal. This input signal is then converted by them into a set of discrete values for performing different operations. These computers prove to be very cost-effective in performing complex simulations. The hybrid computers are also less expensive than the digital computers.The computer used in hospitals to measure the heartbeat of the patient is a very good example of a The computer used in hospitals to measure the heartbeat of the patient is a very good example of a hybrid computer. Apart from this, the hybrid computers are also used in scientific applications, various ure digital computers engineering fields and in controlling business processes.
Based on Application:
Different computers are designed for different purposes so that they can perform their tasks according to their capabilities. On the basis of different applications or purposes, computers can be classified into the following categories:
.General purpose computers
.Special purpose computers
General purpose computers: They are designed in such a manner that they can work in all environments. The general purpose computers are versatile and can store a number of programs meant for performing distinct tasks. However, the general purpose computers are not efficient and consume a large amount of time in generating the result.
Special purpose computers:They are designed in such a manner that they can perform only a specified task. The special purpose computers are not versatile and their speed and memory size depend on the task that is to be performed. These computers are less expensive as they do not contain any redundant information. The special purpose computers are efficient and consume less amount of time in generating the result.
Based on Size and Capability :
Computers differ from each other in terms of their shape, size and weights. Each type of computer performs some unique functions and can be employed in the fields suited for them. These computers also differ in terms of processing speed. Some of them are of moderate speed, whereas some others operate at a very fast speed. On the basis of size and capability, computers can be classified into the following categories:
• Microcomputers
.Mini computers
• Mainframe computers
• Super computers
Microcomputers: A microcomputer is a small and cheap digital computer that is designed to be used by individuals. It is built around a microprocessor, a storage unit and an I/O channel. Apart from these components, the other parts that a microcomputer includes are power supply, connecting cables, keyboard, mouse, printer and scanner. These computers also include several software programs such as operating system, system software and utility software. The micro computers are generally available in the form of PCs, workstations and notebook computers.
Microprocessor : It is the heart of the microcomputer. It incorporates all the functions of a CPU onto a single IC in a microcomputer. The basic units of microprocessor are ALU, register unit and CU. ALU is used to perform various arithmetic and logic operations. The register unit is used to store the data and instructions temporarily needed by the ALU. The various registers used by a microcomputer are Accumulator (AC), program control register, LO register, instruction register, Memory Address Register (MAR) and Memory Buffer Register (MBR). CU is used to manage and direct the operations performed by the microcomputer.
Memory : It is used to store the data and instructions on temporary or permanent basis. A microcomputer generally employs two types of memories, i.e., primary memory and secondary memory. Primary memory. also called main memory, is used to store the data and instructions temporarily. It stores only those instructions and data that are needed by the microprocessor of the computer for processing. The secondary memory, also called auxiliary memory, is used to store the data and instructions permanently. Magnetic disks and magnetic tapes are some of the examples of secondary storage.
Peripheral devices : They are generally the input and output devices attached to the computer. The
various input devices-such as keyboard and mouse-are used to enter program and data into the computer before performing any kind of operation. They are used to transfer data and instructions from the extem environment into the computer. The various output devices-such as monitor and printer-are used to display the results computed by the computer to the user. The major function performed by the outpu devices is to convert the binary result computed by the computer into a form that can be easily understood by the users.
System bus: It is also referred to as the frontside bus, memory bus, local bus or host bus. The system bus in the micro computer is used to connect microprocessor, memory and peripheral devices into single unit. The system bus is a collective name given to address, data and control bus. The address bus is a unidirectional bus that is used to identify a peripheral device or a memory location. The data bus is a bidirectional bus that is used to transfer data among microprocessor, memory and peripheral devices of the computer. The control bus is used by the microprocessor to send control signals to the various devices within the computer.
Depending on the size, the microcomputer can be further classified into the following types:
Desktop computer : It is also known as PC. The desktop computer systems are designed to be used by an individual at a single location. The typical components of a desktop computer are keyboard, mouse, monitor, hard disk storage, peripheral devices and a system unit. These computers are very cheap and an individual can easily purchase them for home or business use. The different manufacturers of desktop computers are Apple, IBM, Dell and Hewlett-Packard (HP).
Laptop computer : It is a portable computer that can be taken from one place to another at any time very easily. It is also known as notebook computer, notepad or mobile computer. The laptop computer is a small size computer that incorporates all the features of a typical desktop computer. These computers are provided with a rechargeable battery that removes the need of continuous external power supply. However,these computer systems are more expensive than desktop computers. The different manufacturers of laptop computers are Acer, Apple, Panasonic, Sony and HP.
Hand-held computer: It is also known as Personal Digital Assistant (PDA), converged device, palmtop or mobile device. The hand-held computer is a very small size computer that can be kept in pocket. It generally has a very small display screen and the input device for these computers is a pen or an electronic stylus. The storage capacity of hand-held computers is not very large. They generally use small cards to store data and programs instead of disk drives. Therefore, they are less powerful as compared to the desktop and laptop computers. The different examples of hand-held computers are Apple Newton, Casio Cassiopeia, Franklin eBookMan, etc.
Mini computers : A mini computer was first introduced in the year 1960 by Digital Equipment
Corporation (DEC). They were called mini computers because of their smaller size than the other computers of those times. They can handle more data and more input and output than micro computers. Mini computers are less powerful than mainframe computers but more powerful than micro computers. Therefore, they are also referred to as the midrange computers. They are able to cater to the needs of multiple users at a single instant of time. The number of users supported by mini computers may range between 4 and 200. These computers are generally designed for small and medium sized business environments.
Mini computers are generally used in business environments as the centralized computer or the network server. After implementing the mini computer as the network server, hundreds of desktop computers can be connected to it. Mini computers can also be used as the web servers that can handle thousands of transactions in a day. These computers are less expensive than mainframe computers and hence suitable for
those organizations that cannot afford high priced servers. The different examples of mini computers are PDP 11, IBM (8000 series), VAX 7500, etc.
Mainframe computers : A mainframe computer is a very large computer that is employed by large business organisations for handling major applications, such as financial transaction processing, Enterprise Resource Planning (ERP), industry and consumer statistics, and census. They are capable of handling almost millions of records in a day. The mainframe computers can also be used as the centralised computers with several user terminals connected to it. The mainframe computers are actually considered as the predecessor of servers. These computers are bigger and more expensive than other computers. The implementation of mainframe computers also requires large space with a closely monitored humidity and temperature levels. These computers are termed as mainframe because all the hardware units are arranged into a frame. The different manufacturers of mainframe computers are IBM, Amdahl, Hitachi, etc. Examples of mainframe computers are IBM 3000, VAX 8000 and CDC 6600.
The mainframe computers çan maintain large databases that can be accessed by remote users with a simple terminal. Therefore, the mainframe computers are also known as super servers or database servers. The processing speed of these computers is generally optimised by employing more than one microprocessor to execute millions of instructions per second. The mainframe computers also have large capacity of primary and secondary storage as compared with other types of computers.
.Some of the characteristic features of mainframe computers are as follows:
.A typical mainframe computer generally has a maximum of 16 microprocessors. However, some modern mainframe computers can have more than 16 microprocessors.
. The RAM capacity of these computers lies between 128 MB and 8 GB.
.They are able to run multiple operating systems, and therefore, termed 'virtual machines.
.They have different cabinets for primary storage. secondary storage and I/O units.
.They can handle huge amount of I/O operations at the same time.
Super computers : A super computer is the fastest type of computer that can perform complex operations at a very high speed. The super computers were first presented in the year 1960 by Seymour Cray at Control Data Corporation (CDC). They are more expensive than the other categories of computers and are specially designed for the applications in which large number of complex calculations have to be carried out to get the desired output. The main reason behind the fast speed of super computers is that they are designed only to execute small number of programs at a time rather than many programs simultaneously. Some of the manufacturers of super computers are IBM, Silicon Graphics, Fujitsu, Intel, etc. Examples of Super Computers are CRAY 3, Cyber 205, NEC SX-3 and PARAM from India.
The various application areas of super computers are as follows:
- Weather forecasting
- Animated graphics
- Fluid mechanics
- Nuclear energy research
- Petroleum exploration
FAQs
What is Computer short answer?
A computer is an electronic machine that takes input from the user, processes the given input and generates output in the form of useful information.
Components of Computers
Central Processing Unit (CPU),Monitor,Keyboard, Mouse.
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