WHAT IS COMPUTER.
A computer is a very versatile electronic machine created by man. Computers have made a great impact on our everyday life. Their presence is felt in almost every aspect of life be it home, school, college, office, industry, hospital, bank, retail stores, railways, research and design organizations, etc.
A computer is basically a programmable computing machine. Earlier computers were used for complex computations. They were costly and hence only large organizations could afford them. Then technological advancements in design and fabrication of semiconductor devices, namely, the microprocessor has made it possible for smaller organizations and even individual's to afford. These computers cannot be asked for faster calculations but also for storing and retrieving information. They can be used to control chemical processes.and machines. They can even measure and display physical and electrical quantities and send photographs electronically.
The word 'computer' comes from the word computer, which means to calculate. So, a computer is normally considered to be a calculating device that can perform arithmetic operations at an enormous speed. But more accurately, it may be defined as a device that operates upon data for calculation.
A computer can, not only store and process data, but also retrieve data, i.e, gather data from its memory or storage as and when required. Thus, a computer is a general term that refers to an electronic data processing machine used for a wide range of activities.
TYPE OF COMPUTER
Analog Computer
Analog computers handle or process information of a physical nature. For instance, temperature, pressure, etc. These are based on the measuring of analog or equivalent physical value.
Digital Computer
Digital computers process information which is essentially in a binary or two-state form, namely, zero and one. In computing terms, we mostly refer to the digital type of computers. Digital computers fall into different ranges called microcomputers, minicomputers, mainframes and supercomputers, which can be further classified in ascending order of size-small, medium, large and very large.
(a) Fast speed of calculations and storing of information
(b) The ability to take in information and store it for future use
(c) The ability to take a variety of instructions for execution of tasks.
(d) The ability to use simple logical rules to make decisions for their own internal control or for the control of some external activity.
(e) The ability to communicate with other computer systems.
(f)To carry out computations and analyse accurately and with speeds
We shall further elaborate the characteristics specified in paragraphs (a), and () above.
Faster Calculation Speed and Information Storage
Computers work at a fast speed without losing their accuracy. Their speed of working is measured in terms of Mips, which is an abbreviation of Mega instructions per second. Thus, when we say that the speed of a computer is 10 Mips, it means that it can process or understand 10 x 10 instructions in one second and execute them accordingly. Another measure of computer speed is in terms of the speed of the microprocessor. Microprocessor is the heart of a computer and execution speed of a computer will depend on the speed of operation of the processor. When we say that the processor operates at 133 MHz speed, it means that the frequency at which the pulses are generated and processed is equivalent to 133 x 10 per second. This frequency of pulses gen- erated is known as the computer's clock speed. A microprocessor based computer with a higher clock frequency will operate faster than the one with a lesser clock frequency.
Ability to take Variety of Instructions
With the advances made in the field of computers, a programs can be written by using a small set of instructions which can per- form very complex manipulations. Some of the application pack- ages have pre-defined functions and procedures. You will need to give the argument for these functions or procedures and they will immediately execute and give you the results. For instance, the spreadsheet package namely, MS Excel has built-in-functions which can calucate standard deviation and variance on a set of data items. Such functions can take a lot of time when calculated manually. However, with a computer one can do all such calcula tions in a split of a second. These software programs also contain sets of instructions to develop macros. Macros can be developed even by those who know very little about programming
Carry Out Computations Accurately
Computers can be relied upon for accurate results. How ever, the accuracy depends on the method of programming and the way the results are interpreted. The accuracy also depends or the type of machine you employ. For instance, a microcomputer may give accuracy of results upto 16 decimal places only whereas a mini- computer may give an accuracy up to 32 decimal places.
ANATOMY OF A COMPUTER
The five major functional units of a digital computer are:
(a) Central Processing Unit (CPU)
(b) Input units
(c) Output units
(d) Storage devices
(e) Communication interface
CPU is the brain of a computer. The other parts are used to transfer data and to communicate with the CPU. The CPU constitutes the main memory, control unit and arithmetic logic unit.
In this Figure, the solid lines are used to indicate the flow of instructions and data. The dotted lines represent the control exercised by the control unit. The Figure shows the basic arrangement of different units of a computer. It depicts the five major building blocks, or functional units of a digital computer system. These five units correspond to the five basic operations, namely, input- ting, storing, processing, outputting and controlling data, carried out by all computer systems. The five units are explained in brief as given below.
Inputting: Refers to the process of entering data into the computer with the help of, an input device, such as a keyboard.
Storing: Refers to the storage of data and instructions in the computer's main memory, for manipulations.
Processing: Refers to performing operations (both arithmetic and logical) or manipulation of data entered into the computer so that useful information may be gathered from the entered data.
Outputting: Refers to the process of showing the information or result to the user either on screen (monitor) or on paper (through printer).
Controlling: Refers to directing all the above processes, in coordination. This controlling is done by the Control Unit (CU) in a CPU.
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