Its an electronic Device that is used for information Processing.
Computer.. Latin word.. compute
A computer system includes a computer, peripheral devices, and software
Accepts input, processes data, stores data, and produces output
Input refers to whatever is sent to a Computer system
Data refers to the symbols that represent facts, objects, and ideas
Processing is the way that a computer manipulates data
A computer processes data in a device called the central processing unit (CPU)
How Computer Works
Definition: Computer Computer can be defined as “An electronic and electromechanical device capable of receiving data, processing the data inputted, and generating the output in the form of information”. In the definition, we come across some terminologies such as electronic, electromechanical device etc. An electric device is that device which runs by electricity. An electromechanical device is one which performs mechanical movements upon receiving the electricity. Whatever we are inputting into the computer will be treated as Data and whatever has been generated by computer will be treated as Information.
Characteristics of Computers
Main characteristics of the computer can be summarized as:
1. Speed: Computer is very fast and accurate device. It can process millions and millions of instructions within
2. Accuracy: Computer results are highly accurate.
3. Memory: Computers have a large amount of memory to
hold a very large amount of data or information.
4. Programmed Intelligence: Computer themselves as such are dumb terminals. But they are programmed in such a way that they can perform those operations which have been fed into them in the form of executable programs.
5. Diligence: Computer is free from problems like lack of
concentration, and confusions etc. Computer may never be confused like humans.
6. Versatility: We can perform many different types of tasks on computer. One moment it might be busy in calculating the statistical date for annual performance evaluation of a business organization and next moment it might be working on playing movies.
7. Power of Remembrance: Unlike humans, computer can store things for unlimited period of time.
Types of Computers
There are two basic kinds of computers: analog and digital .
Analog computers - Analog computers are analog devices. That is, they have continuous states rather than discrete numbered states. An analog computer can represent fractional values exactly, with no round off. Analog computers are almost never used outside of experimental settings. They handle or process information, which is of physical nature.
Electronic analog computers generally in chemical plants monitoring temperatures, pressures, voltage, etc.
Now these days, we rarely came across of analog computers in routine life.
Digital Computer - Digital computer is a programmable-clocked sequential state machine. A digital computer uses discrete states. A binary digital computer uses two discrete states, such as positive/negative, high/low, on/off, used to represent the binary digits zero and one. They process data, which is essentially in a binary state.
In other word digital computer refer to a computer, which represent, the data, whether numbers, letter, or symbols, in binary form and they work with numbers in the form of separate discrete digits.
Hybrid Computer – It refers to computer that contain both digital and analog circuit.
for ex. A digital thermometer employs a mechanism which converts the temperature into digital form observed in analog signals using to analog-to-digital conversion.
Classification of Computers
Micro Computers - A microcomputer’s CPU is a microprocessor.
The microcomputer originated in late 1970’s. The first microcomputers were built around 8-bit microprocessor chips. What do we mean by an 8-bit chip?
It means that the chip can retrieve instructions/data from storage, manipulate, and process an 8-bit data at a time or we can say that the chip has a built- in 8-bit data transfer path. 8088 was a 8/16 bit chip i.e. an 8-bit path is used to move data between chip and primary storage (external path), but processing is done within the chip using a 16-bit path (internal path) at a time 8086 is a 16/16 bit chip i.e. the internal and external paths both are 16 bit wide. Both these chips can support a primary storage capacity of up to
1 Mega byte (MB).
Minicomputers The term minicomputer originated in
1960s when it was realized that many computing
tasks do not require an expensive contemporary
mainframe computers but can be solved by a small, inexpensive computer. Initial minicomputers were
8 bit and 12 bit machines but by 1970’s almost all minicomputers were 16 bit machines. The 16 bit minicomputers have the advantage of large instruction
set and address field; and efficient storage and handling of text, in comparison to lower bit machines. Thus, 16-bit minicomputer was more powerful machine, which could be used in variety of applications and could support business applications along with the scientific applications.. The minicomputer was then used as a multi-user system,
which can be used by various users at the same time.
Workstation - is a powerful stand-alone
computer of the sort used in computer aided design
and other applications requiring a high-end, expensive machine with onsiderable calculating or graphics
capability. Machines using Intel Processor P2 at 400
MHz is an example of workstation. Now these days computers having P-4 or AMD Athlon type microprocessor also comes in the classification of workstation.
Mainframe Computers - are very powerful,
large-scale general-purpose computers.
Their word length may be 64 bits, memory capacity being in some megabytes and storage capacity in some terabytes etc. They are used where large amount of data are to be processed or very complex calculations are to be made and these tasks are beyond the capacities of mini computers.
They are used in research organizations, large industries, airlines reservation where a large database has to be maintained. Examples are IBM 4300 series, IBM Enterprise
processing capabilities lies in the
range of GIPS2, word length 64-128 or may be in 256 or so.
Memory capacity in some gigabytes or in terabytes and
storage capacity in pixabytes. It contains a number of
CPU’s, which operate in parallel to make it faster, giving
them their speed through parallel processing . They are
used for weather forecasting, weapons research and
development, rocketing, aerodynamics, atomic, nuclear and
plasma physics. Supercomputers have limited use and
limited market because of their very high price. They are
being used at some research centers and government
agencies involving sophisticated scientific and engineering
As being man made machine, computer also has some
limitations. These are:
It cannot think : Scientists are working very hard to enable
computer to think. Some achievements have been seen in
this area in the form of MYCIN etc. But to the bottomline,
we can state that an average computer which is used
extensively used now these days, does not possess thinking
capabilities of its own.
It can not manage self : A computer by itself can not
manage self in terms of managing self against errors or
performing required operation/recovery in catastrophe