What are the basic differences between the four generations of computers? Give two examples of the first-generation computers.
Answers
Explanation:
Over the years, many computing devices were invented that are used by the humans to solve different types of problems. All these computing devices can be classified into five generations which refer to the phases of improvement made to different computing devices resulted in a small, cheap, fast, reliable and productive computer. The technological development in the field of computers not only refers to the improvements made to the hardware technologies, but also the improvements made to the software technologies
First Generation(1940-1956)- The first generation computer used the vacuum tubes technology for calculation as well as for storage and control purposes. So these computers are also called as vacuum tubes or thermionic valves based machines. A vacuum tube, as shown in fig. 1.1, was a fragile glass device, which used filaments inside it. The filaments when heated generate electrons, which eventually help in the amplification and deamplification of electronic signals. These vacuum tube computer could perform computer in milliseconds. The memory of these computer was constructed using electromagnetic relays, and all data and were written in machine and assembly language because high-level programming languages were introduced much later. These first generation computer were mainly used for scientific computations. Some examples of these computers are ENIAC, EDVAC, EDSAC, UNIVAC I and IBM 701.
Second Generation(1956-1963)- A new electronic switching device, called transistor, was invented at Bell Laboratories in 1947 by john Bardeen, Willian Shockley and Walter Brattain for which they won the Nobel prize. A transistor, as shown in fig.1.2, is a semiconductor device that is used to increase the power of the incoming singals by preserving the shape of the original signal. It has three connections, which are emitter (E), base (B) and collector (C). The base of transistor is the gate through which the signal, needed to be amplified, is sent. The signal sent through the base of the transistor is generally a small flow of electrons. Therefore, the base terminal also acts as the input gate for the transistor. The collector of the transistor is used to collect the amplified signal. The emitter of the transistor acts as the output gate for emitting signal to the external environment. The second generation computers were manu8factured using transistor in place of vacuum tubes to build the basic logic circuits. Transistors used in second generation computers were smaller, faster, cheaper and generated less heat than that of vacuum tubes. Transistors were also light weight electronic devices that required very less power during their operation. These characteristic features of transistors made the second generation computer more powerful, more reliable, less expensive, smaller and cooler to operate than the first generation computer. Printers, secondary storage and operating system technology were also invented during this era.
The memory of these computer was composed of magnetic cores. Magnetic disk and magnetic tape were the main secondary storage media used in second generation computers. Punched cards were still popular and widely used for preparing programs and data to be fed to these computer. Another major technological development made to these computers was the replacement language. Assembly language is a low-level language that allows the programmer to use simple English word-called mnemonics-to represent different instructions in a program. The introduction of batch operating system allowed multiple jobs to be batched together and submitted at a time and automatic transition from one job to another, as soon as the former job finished. This concept helped in reducing human intervention while processing multiple jobs, resulting in faster processing, enhanced throughput and easier operation of second generation computer. In second generation computer, an increasing usage of computers was seen in business and industry for commercial data processing applications like payroll, inventory control, marketing and production planning. Some examples of second generation computers are PDP-8,IBM 1401 AND IBM 7090.
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