Generation of Computer

1st year B.Sc in nursing

Subject: Computer & IT

Computer Generations

Development over the years have resulted in machines with greatly increased speeds, storage, memory, and computing power. The developments were so far-reaching and numerous that they are generally categorized by generations. Each generations is initiated by significant advance in computer hardware of computer software.

First Generation (1942-1959)

First Generation computers utilized vacuum tubes in their circuitry and for storage of data and instructions. The vacuum tube was bulky, caused tremendous heat problems, and was never a reliable device and inefficient operations. Magnetic cores began to replace vacuum tubes as the principal memory device in the early machines. Programs were written in machine language employing combinations of 0 and 1. Examples of first generation computers are IBM 650, IBM 704, IBM 705, IBM 709, Mark II, Mark III etc.

Second Generation (1960-1965)

The second generation computers saw the replacement of the vacuum tubes by transistors. A transistor  can be thought of as a switch, but with no moving parts. Because of high speed operation and small size, computers of this generation  could perform a single operation in microseconds and were capable of storing tens of thousands of characters. Manufacturers began producing business-oriented computers with more efficient storage and faster input and output capabilities. Second generation computers were reliable, compact in size, and virtually free of heat problems. Programming was done in both in both machine and symbolic language. Symbolic language utilize symbolic names for computer commands and allow the use of symbolic names for items of data. This language is also known as assembly language. Examples of second generation computers are : IBM 1400, CDC 1604, RCA 501, NCR 300, GE 200, IBM 1600 etc.


Third Generation (1965-1971)

These computers were characterized by integrated circuits with components so small. Third Generation computers were characterized by increased input/output, storage and processing capabilities. Input/output devices could communicate with computers over distances via ordinary telephone lines or could scan a page and input the information directly into the computer, could display pictures on a television-like screen, could make musical sounds, and could even accept voice input.

Storage capabilities were increased and millions of characters could be stored and randomly accessed in fractions of a second. Third Generation computer could process instructions in nanoseconds. Programmers were able to make use of high level problem oriented and procedure oriented languages that closely resembles the commonly used form of expression. Examples of Third Generation computer are IBM 360, IBM 370, PDP-8, GE 600 etc.

Fourth Generation (1972-Present)

Fourth Generation computers possess still greater input/output, storage, and processing capabilities. In the Fourth Generation computers, semiconductor storage devices were introduced. In the early 1970s IBM introduced the concept of virtual storage into their 5000 and 370 series of computer. One million characters now possessed a virtual storage capability in billions and trillions of characters. With this capability a machine could execute a program many times the size of the machine’s actual memory. Microcomputers using microprocessors as the CPU in the fourth generation.Now a days, the compact disk (CD) to become the data storage medium of choice. A Compact disk read-only memory (CD-ROM) is encoded with on and off bits. Bits are stored on the disk’s (3.5- inch diameter). The average CD can store about 4800 million bits or 600 million characters of data.

The most impressive advancement has occurred in software. As a result of these changes access to substantial computer power, very large business concerns, is now economically feasible for small business and personal applications.

Fifth Generation

Fifth Generation computers is yet to come. They will be capable of reasoning learning, making inferences and behaving in ways considered exclusive of humans. These computers will be equipped with massive primary storage capabilities and extremely fast processing speeds. Software will get much bigger. Hardware will continue to internal memory will increase dramatically. Expert systems software will place the knowledge of experts and consultants (Such as doctors, lawyers and teacher) at the disposal of general users. Huge number of computers will be linked in parallel offering computing power. Artificial intelligence will be used extensively to enhance the system behavior in th future.


Md. Tariqul Islam

B.Sc (Hons.), M.Sc., CSE & CCNA


Computer & IT


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