Classifications of computers on the basis of capacity, purpose and genreration
Answers
Classification based on purposes:
There are either special-purpose or general-purpose computers. A special-purpose computer is designed for a specific application. It is also known as dedicated computer. Many such computers have instructions permanently programmed into them that are designed to perform only one major function. Special-purpose computers are used to control traffic lights, to control the collection of tolls on highways, and in automobiles, weapons, appliances and games etc.
General-purpose computers are used to handle a variety of tasks. This is possible by the stored-program concept. By this concept, a program containing a series of instructions is prepared for an application and temporally stored in memory. Once stored in the computer’s memory, the program can be executed to perform the specific function. After the completion of the execution of one program, another program can be used for some other task. That is, the same hardware can be used to execute many different programs.
General-purpose computers are more versatile than special-purpose computer. But when applied to the same task it is seen that general-purpose computers are less efficient and also slower than special-purpose computers
Classification based on capacity:
Capacity of a computer refers to the volume of data that a computer system can process. Formerly a computer’s size was a sign of its capacity. With the current state of smallness, dimension of capacity is based on throughput of the computer. Throughput is the quantity of processing that can be performed in a given amount of time. Based on throughput computer systems can be divided into four major categories:
Microcomputers
Minicomputers
Mainframe computes
Supercomputers
Microcomputers:
Microcomputers are generally known as personal computers-PCs and are microprocessor based small notebook or laptop or desktop systems with changeable capacity. Personal digital assistants (PDAs) are very small portable computers. PDAs are also recognized as the palmtop computers. The brain of a microcomputer is the microprocessor; it is a silicon chip containing essential circuits to execute logic or arithmetic operations and to manage the input/output operations. A microprocessor is an integrated circuit which usually contains millions of transistors squeezed onto a small silicon chip. A microcomputer system is formed by adding input and output facility along with memory to the microprocessor.
Microcomputers
At the initial time the microcomputers had very limited processing power and limited choice of input/output devices. But at modern days they have wider processing capabilities and maintain a wide range of input/output devices. Today microcomputers are available with a collection of input/output devices varying from a tape recorder to a voice synthesizer. In addition to general-purpose computations, microcomputers are also used for exceptional purpose applications in automobiles, airplanes, toys, clocks, appliances etc.
Servers: Servers are not designed to be used directly. They make programs and data available for users having access to a computer network. A computer network is a collection of computers connected together.
Minicomputers:
A minicomputer system performs the basic arithmetic and logic functions and supports some of the programming language used with large computer systems. They are physically smaller, less expensive, and have small storage capacity compared to mainframes. Minicomputers are ideally suited for processing tasks that do not require access to huge volumes of stored data. As a result of low cost, ease of operation, and versatility, minicomputers have gained repaid acceptance since their introduction in the mid-sixties. Some of the larger and expensive minicomputers are capable of supporting a number of terminals in a time-shared mode. Uses of minicomputers are gradually being diminished with the rapid development of microcomputers.
Minicomputers
Mainframe Computers:
A larger computer normally consists of modules accumulated on a chassis and is terms as a mainframe computer. They differ in size, from those a little larger than a minicomputer to supercomputers. These computer systems present extensive benefits over minicomputers or microcomputers. Some of these are: greater storage facility, greater processing speed, a larger assortment of input/output devices, and support for a number of high-speed storage devices, multiprogramming, and time sharing.
Supercomputer:
A very powerful and large mainframe computer is known as a supercomputer. The astronomical cost of super-computers has limited their development to only a few hundred worldwide. The example of a supercomputer is the Cray X-MP. Such supercomputers are applied to the solution of very difficult and complicated scientific and technical problems. Supercomputers are also used for the various national security purposes of some advanced nations.
The computers can be classified in the below four categories:
• Super Computer: These are the biggest, super expensive and fastest computers in the world. Theses are generally used in weather forecast, military researches etc. Example: ANURAG, CRAY XMP/14 etc.
• Mainframe Computer: These are largest computers in the world. They are generally used in Card processing, Bank account management etc. Example: IBM S/709, ICL 39 etc.
• Mini Computer: These are medium sized and middle ranged computers. They are generally used in university, business organizations etc. Example: PDP-11. VAX etc.
• Micro Computer: These are general purpose computers having vast usages in common life. Example: Apple MAC etc.