They were based on the principles of standardization and compatibility. the third generation computers also permitted multi programming which was intervolved processing of several programmers to enhance the productivity of computers, time sharing which s the use of customer by several customers at a time, operating systems which optimizes the man machine capabilities and such data communications facilities like remote terminals, etc. these computers had higher processing speed, they used data base software And were very convenient and reliable than second generation computers.

Mainframe computers are less powerful and cheaper than super computers. However, they are big general purpose computers capable of handling all kinds of scientific and business applications. Mainframe computers can process at several million instructions per second. They can support more than one thousand remote terminals. They have an online secondary storage capacity and also facilitate multiprogramming and time sharing.

They used magnetic tapes as input and output media or devices and used higher level language and operating system. Because of use of higher level language COBOL and FORTRAN, computers can be used by variety of users and organizations. The transistors were far superior mode of power supply and operating capabilities from vacuum tubes. The second generation computers also moved to symbolic languages from binary machine language. So, they were smaller in size compared to first generation computers and generated lower level of heat and had greater degree of reliability that first generation.

Microcomputer is a fully fledged computer system that uses a microprocessor as it CPU; these are also called personal computers. Microcomputers were first available for use in 1970s. Chip refers to any self-contained integrated circuit. a microcomputer is often called micro because it is small in size and containing small processor on a single silicon chip which is mounted on a circuit board with other chips containing the computer’s internal memory in the form of read only memory and random access memory.

One of the most significant development f fourth generation computers was the invention of micro computer or personal computers.

The microprocessors were used in fourth generation of computers as thousands of integrated circuits were built onto a single silicon chip. These were more compact and smaller in size than of third generation computers. These have enhanced capability of input and output devices and also used developed user friendly operating systems and software. They use hard disk as storage device, uses Local Area Network and Wide Area Network for information sharing purpose.

They were slow in processing and low speed input output devices. They also required more electrical power and were very costly also.

They consumed a large amount of power on start up and shutting down. These are universal Automatic Computer. The input and output units were the punched card readers and the card punches. These were used in 1940 and ran till 1956 with magnetic drum memory and punched cards for input and output. It was intended both for business and scientific applications.

According to it, the future generation computers will be able to recognize voice as input and will be able to accept the spoken words instructions and imitate human reasoning. They will be based on Artificial Intelligence and will be as matured as they can even think like human mind. They will be more powerful and compact than all previous generations of the computers. they will be well equipped to do every single task which a human can do and will get specialty in many fields as specialists computer systems which can handle each and every task or function to be performed.

Thereafter the user defines the further processing and use of the output data, whether it is stored in the system and accessed in later future or it should be further processed to get other results. So, in this way, computer is the electronic device used to process and store the data and in order to enhance the reliability at the time of accessing the data and information processed.

Keyboard is the input device which is used to input data and gives instructions on the processing of data. Monitor is a hardware device which is also called output device used to see the processed data. It is output device contains digital screen at which the user can see the final information got from processing. Memory is also one main component of computer. There are two types of memories called Read only memory and random access memory.

Behind all it various advantages, computer also suffer from some shortcomings too. These shortcomings are related to reliability. Computers are used for programming and nothing else. All the programs are manmade and there is also a probability of error present in human actions. So, it is limited to some shortcomings. Computer is an electronic device and every electronic device has its own definite life cycle and usable time. so, it has also a limitation of usability period.