A computer is an electronic device that accepts stores and processes data into information that the user can understand. Computer is a general name consisting of very many devices like desktops, notepads, calculators and many others. Generally computers are classified according to:
•Number of processors
According to size there are several computers involved this include:
•Super computers- these computers require a lot of mathematical calculations. They also produce very large amount of data. They also have specialized applications that need large mathematical calculations. Examples of where a super computers are used is when weather forecasting, when the military wants to test the new air crafts, scientist use it to test the effects of a nuclear weapon, in Hollywood they use the super computers to create animations and researchers also use them to compute the biological compounds like the blood. Some examples include Jaguar, Tianhe, Roadrunner and Sunway TaihuLight.
•Main frame computers- these are computers that are very large in size and very expensive. Their data processing speed is very high. They are mini super computers. They are more powerful than super computers because they are able to support many programs at once. They are used in online electric transactions, they perform in ATM machines in deposits and withdrawals and also is census and in electoral purposes. Some examples include Hitachi’s Z800 and System Z9.
•Minicomputers- these are a bit smaller than the microcomputers. It is capable of supporting around 200 users simultaneously. They are mainly used for controlling and manufacturing activities, monitoring laboratory equipment’s and also used as the switch board control. Some examples include Micro VAX II and Texas Instrument TI-990.
•Microcomputers- these computers are a bit smaller than the super computers and main frame computers. They include the desktop computers, palmtop computers and laptop computers.
•Mobile computers- everyone else has the mobile computers. They include mobile phones, notebooks, midsized laptops and calculators.
•Embedded Systems- this are computers that are electronic designed to do dedicated tasks. They are a combination of the software, outer hardware and a microprocessor chip. The microprocessor is what does the task. Some examples of the embedded systems are printers, digital cameras, ATM machines, thermostats and digital watches.
According to age the computers are divided into:
•1st generation of computers- they are computers between the years 1946-1957. They used the vacuum tubes. They used magnetic drums for storage.
•2nd generation of computers- they are computers between the years1958-1964. They used transistors. The operating system was faster and they had programming languages.
•3rd generation of computers- these are computers between the years 1965-1971. They used the integrated circuits. They were smaller because there was the introduction of the chip. Their processing speed was higher.
•4th generation of computers- these are computers between the years 1972-1990. They used the large scale integration. The memory size was big thus processing speed of data was fast.
•5th generation of computers- these are computers between 1990 till to date. Most of them are still being developed. They use the very large scale integration technology. The speed of these computers is extremely high.
According to purpose the computers are divided into two:
•General purpose computer- these computers serve and solve a wide variety of tasks. They are said to be multi-purpose. They store very many programs but are slow in speed and they lack efficiency. They can be used to manage inventories, print sales and also pay bills. They include laptops and desktops.
•Special purpose computers- these computers that solve on specified problems and dedicated tasks. They have a set of instructions that Is inbuilt in the computer. They include calculators and money counting machines
According to processing, there are several computers in this category these include:
•Digital computers- this are computers that process data in form of discrete values. The results are very accurate and are produced very fast. They also do calculations and logical operations using the binary system. Some examples include calculators.
•Analogue computers- they use the physical phenomena such as mechanical and electrical quantities to the problem at hand.
•Hybrid computers- this is a combination of analogue and digital computers. They are able to work both the digital and analogue way.
According to number of processors, they are divided in to two which include:
•Parallel Computers- they are very fast and use a large number of processors. The processors perform different tasks therefore increasing the speed of executing programs. They are equal to the supercomputers.
•Sequential computers- this are computers where they perform one task after another. A next task cannot be done without completion of the current task. The work according to the instructions in the computer.