CLASSIFICATION OF COMPUTERS Computer can be classified based on the way they operate or represent data. On the basis, there are three types, namely: * Analogue Computer. * Digital Computer. * Hybrid Computer.
a. ANALOGUE COMPUTERS: There are computers that are used for measuring changes in physical state of a thing. It represents data in terms of Physical measures or quantities such as temperature, speed, volume and weight. Examples of analog computers and related equipment are car speedometer, measuring scale, thermometer, liquid dispenser (fuel pump) and electric meter, analog wristwatch, aero plane speedometer. etc.
b. DIGITAL COMPUTERS: These are types of computers that are used for counting and calculating. They use discrete forms or binary systems (0s and 1s) to represent data. They store data in terms of digits (numbers). As a matter of fact, anything that counts number produces integers and series of numbers or digits are digit equipment. Examples of digital computer related object are adding machine, calculator, digital wristwatch and hospital thermometer. While examples of digital computers are mainframe, mini computers and micro computers.
c. HYBRID COMPUTERS: These are computers that combine the functions of both analog and digital computers together. They measure and can as well be used for counting and calculation. They exhibit features of analog and digital computers in a single computer system. Hybrid computers are used for complex operations. Hence, many people cannot use them and they cannot be seen easily in the market like the types.
CLASSIFICATION OF COMPUTER SIZES
Computer comes in different sizes and shapes. Hence, it is easy to classify computer based on their sizes. Under this classification, computers are grouped into four namely Super computer, mainframe computer, mini computer and micro computer.
These are the biggest, fastest and most expensive types of computer with enormous power and speed. They are also known as "Monsters” or "Maxi” computers. They by scientists for research purposes. They can processes up to a billion instructions per second. Examples are CRAY X/Y models such as Cray X-MP etc.
Features of Super Computers
i. They are the largest and biggest of all computers ii. They are the fastest known computers. iii. They are the most powerful. iv. They use enormous power. v. They have speed and storage capacity.
Uses of Super Computer
i. They are used for scientific and military applications and researches. ii. They are used for space exploration, oil exploration, simulations (guessing) and weather forecast. iii. They are used by large organizations for manufacturing purposes. iv. They are used for processing large files and performing large scale mathematical calculations.
MINI COMPUTERS: These are mid-sized computers. They are less powerful than the super and mainframe computers. They require less flour space and are easier to install and operate. They can perform many tasks at the same time. Examples are IBM 38, NCR 9300 and MV400.
Features of Mini Computers i. They are smaller and portable than mainframes. ii. They are cheaper. iii. They are used for specific or special purposes. iv. They have smaller memory. v. They have lower processing speed and storage capacity than super computer or mainframe computers. Uses of Mini computers
i. They are used for specific purposes. ii. They are used by some medium – size companies for manufacturing purposes. iii. They are used to meet data processing needs such as accounting. iv. They are used for research purposes.
MAINFRAME COMPUTERS: Mainframe computer are big and fast computers with high processing speed and data storage. They are very expensive. They require a humid environment such as an air conditioned room and a large floor space to function properly. Examples of mainframe computers are NCR – 8800, DBM 360/370 etc.
Features of Mainframe Computers
1. They have very high processing speed but they are slower than super computers. 2. They are less powerful than super computers. 3. They have large memory and storage capacity. 4. They are also very expensive but less expensive than super computers. 5. Mainframe computers accept the connection of large numbers or remote computers.
Uses of Mainframe Computers
i. They are used by large organizations such as banks, universities, research institutes and government establishments for their operations. ii. They are used by examination bodies such as NECO, WAEC and JAMB (now UTME) to mark students’ scripts and to process results. iii. They are used for processing large data. iv. They are useful in large network of individual point of terminal. v. They are used for updating inventories.
MICRO COMPUTERS Micro computers are the smallest computers. They are popularly called "Micros” as a result of a component called micro processor contained in their Central Processing Units. They are the commonest computer in all areas of life and the most widely used. They are also called Personal Computers (PC) because they can only be used by one person at a time. There are different types of micro computers depending on their sizes. These include:
1. Desktop Computer: It id placed on the top of a desk or table for use. This is from where it got its name. Desktop computers are the biggest and the commonest types of micro computers. They have very high storage capacity and speed. They support the use of other computer hardware components.
Features of Micro Computers i. They are smaller than other types of computers. ii. They are the least expensive. iii. They are not portable.
2. Laptop Computer: It is called laptop because it can be placed on the laps during use. It can be easily carried about in a special briefcase, thus providing mobile computing technology. It can be either electricity powered. Its greatest advantage is its mobility. That is, it can be carried around. Laptops are costlier than desktop computers.
Uses of Laptop Computers
i. A laptop is mobile and portable. ii. It is very fast in data processing. iii. It is useful in all areas of life. iv. It can be used at anytime because it can be powered with batteries. v. It is used to watch films and to listen to music, vi. It used for various data analysis.
Notebook: It is a very light and small PC. It looks like laptop computer but it is small as a textbook. It has all the capabilities of a PC in terms of speed, data processing and storage.
Uses i. It is used for browsing. ii. It is used for data processing. iii. It is portable and convenient to use. iv. It is useful in listening to music and watching films. v. It is used for data analysis. vi. It can be used at any time since it is battery powered.
Palmtop Computer: It is the smallest type of micro computer. It is so small that it can be placed on one’s palm for use. Palmtops are sometimes called "Organizers”. They are also as powerful as the desktop. They have sensitive screen and use electronic writing pad.
Uses i. It is used for storing addresses and telephone numbers of people. ii. It is used to keep daily records of one’s activities. iii. It is used to store important events and dates. iv. Its soft touch sensitive screen frees users from the constraints of a keyboard.
CLASSIFICATION OF COMPUTER BY GENERATION
From the time of Charles Babbage, there have been several developments in the computer world known as computer generation. There are five generations of computer, namely:
1. FIRST GENERATION COMPUTER: They were built between 1945-1959. These computers were very big, expensive, slow and produced too much heat. The first generation computer used vacuum tubes. Examples are Electronic Numerical Integration and Calculation (ENIAC), Universal Automatic Computer (UNIVAC), EDSAC and EDVAC.
Features of First Generation Computers i. They are very big and occupied large spaces. ii. They made a lot of noise. iii. They had limited storage capacity in magnetic tape. iv. They were expensive to buy. v. They generated a lot of heat. vi. They made use of vacuum tubes. vii. Punched cards were used to input information.
SECOND GENERATION COMPUTERS: They existed between 1960 – 1965 and used transistors in place of vacuum tubes. Examples are IBM 7090 series, Leo Mark, Atlas and IBM 1401,
Features of Second Generation Computers i. They were smaller in size and faster than the first generation computers. ii. They use transistor instead of vacuum tubes as electronic components. iii. They generated less heat. iv. They had higher storage capacity. v. They were less expensive and more reliable than first generation computers. vi. They required air - conditioning.
THIRD GENERATION COMPUTERS: They existed between 1966 – 1975 and were a great improvement upon the past generations of computers. They used integrated circuits in place of transistors and diodes and were the first generation of computers to use the keyboard, monitor and mouse. Examples are IBM 360 series, CDC 6600 and ICL 1900.
Features of Third Generation Computer i. They were smaller in size and faster than the second generation computers. ii. They used integrated circuits (IC) instead of transistor. iii. They were easy to use. iv. They had higher storage capacity. v. They were less expensive. vi. Monitors and keyboards were introduced as input and output devices. vii. They made use of high level language.
FOURTH GENERATION COMPUTERS: These are sets of computers were built between 1975 – 1990. Some of them are the micro computer we see today such as desktops and laptops. Their significant characteristics is the development of large – scale integration which implies the combination of many components (more than 100) together. Features of fourth Generation Computers i. They have micro processors. ii. They are smaller in sizes. iii. They are users friendly and interactive. iv. They are less expensive and portable. v. They employ large scale integrated circuits (LSIC). vi. Air conditioning is not a must for their use.
FIFTH GENRATION COMPUTERS: These are the latest, recent and future generation of computers. They came into existence as from 1990 till date. They use artificial intelligence and are capable of performing many tasks like humans. They involve technological advancements in the field of voice recognition, optical disk, fibre optic networks, internet and virtual reality. They are reliable and can take decisions. Examples are Apple GA, Linux etc.
Features of Fifth Generations Computers i. They have artificial intelligence (AI). ii. They have very large scale integrated circuits (VLSI). iii. They are reliable and can take decisions. iv. They copy or mimic human senses and perform human activities. v. They recognize human voice and respond to instructions.
CLASSIFICATION OF COMPUTER BY PURPOSE
Computers can be classified based on the purpose or task they are designed or used for. Based on this, computer can also be classified as: i. Special Purpose. ii. General Purpose.
SPECIAL PURPOSE COMPUTERS
A special purpose computer is a computer that is designed to perform one specific function or task. It cannot be used for any other thing. Examples of special purpose computers are home appliances such as MP3 player, washing machine and microwave. Others are airplane control machine, weather forecast machine, automated teller machine (ATM), gasoline dispenser, speedometer, and traffic light system machine.
Features of Special Purpose Computers
Most of them are too bulky and cannot be easily carried from place to place. i. They require constant power supply. ii. They are not versatile and can hardly perform any function other than what they were designed to designed to do. iii. They perform specific task quickly and efficiently. iv. The output is economical and cheaper.
GENERAL PURPOSE COMPUTERS A general purpose computer is a computer that is designed from the scratch to do many different tasks depending on the user. All personal computers (micro computers) are general purpose computers.
Features of General Purpose Computers i. They are very versatile. ii. They can be easily carried about. iii. They are not bulky. iv. They do not require large space to operate. For example, the palmtop computer can be operated on a space as small as the top of the user’s palm.