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 generation is initiated by significant advances in computer hardware or 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 bully, caused tremendous heat problems, and was never a reliable device, it caused a great number of breakdowns and inefficient operations. [Magnetic cords began to replace vacuum tubes as the principal memory device in the early machine. Small doughnut-shaped cores were strung on wires within the computer.] Programs were written in machine language employing combinations of 0 and 1. Examples of first generation computers are IBM 650, IBM 7O4, IBM 705, IBM 709, Mark II, Mark III etc.
• Second Generation (1960-1965) The second generation computers raw the replacement of the vacuum tubes by transistor can be thought of as a switch, but 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. [Manufactures began producing business-oriented computers with more efficient storage and faster input and output capabilities. Second generation computers efficient storage and faster input and output capabilities. Second generation computers were reliable, compact in size, virtually free of heat problems.] Programming was done in both machine and symbolic languages. Symbolic languages 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 component so small that in many cases they were hardly visible to the naked eye. Third generation computers wre 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 said and input the information directly into the computer even accept voice input.
Storage capabilities wre increased and millions of characters could be stored and randomly accesssed in fractions of a second. Third-generation computers could process instructions in nanoseconds. In addition, computers were able to process several programs or sets of instructions simultaneously. Programmmers were able to make use of high-level problem oriented and procedure oriented languages that closely resembles the commonly used form of expressions. Examples of third generation computers are IBM 360, IBM 370, PDP-8, PDP-11, GE 600 etc.
• Fourth Generation (1972-Present) The fourth generation computers posses 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 computers. Machines previously limited to a maximum internal 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 proliferated in the fourth generation.
Now a days, the compact disk (CD) promises 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) aluminum surface as tiny pits at varying depths. The average CD can store about 4,800 million bits or 600 million characters of data. This is approximately a quarter of a million pages of text.
The most impressive advancement has occured in software. As a result of these changes, access to substantial computer power, previously only affordable by very large business concerns, is now economically feasible for small business and personal applications. Personal computers are examples of fourth generation microcomputers.
• Fifth Generation
Fifth generation of computers is yet to come. They will be capable of reasoning, learning, making inferences and behaving in ways usually considered exclusive of humans. These computers will be drugsed with massive primary-storage capabilities and extremely fast processing speeds. Software will proliferate and get much bigger. Hardware will continue to shrink in size but internal memory will increase dramatically. "Talking machines" will be common place. Voice-recognition, the ability for a machine to understand and obey spoken words will be developed. Industrial and personal robots will roll and wall. Experts systems software will place the knowledge of experts and consultants (such as doctors, lawyers and teachers) as the disposal of general power of an inconceivable magnitude. Artificial intelligence will be used extensively to enhance the system behavior in the future.