Computer Fundamentals - DailyGgist

What is computer?

Generally, a computer can be defined as an electronic device that accepts data as input, processes the data and generates results as output. The data given to the computer as input are processed using a set of instructions called program. The instruction in the program directs the computer on how to arrive at the result and thus, generate the expected output called information.

Computer classification

Computer are classified using criteria namely by: nature of matter, size generation and purpose. The following sections discuss these classification.

Classification by Nature of Data

There are two types of data the computer can process. They are Digital and Analogue.

Computer types can be classified into three. These are :

• Analogue Computer
• Digital Computer
• Hybrid Computer

1. Analogue Computer: This type of computer deals with quantities that are continuously varying. It measures change in current, temperature or pressure and translates these data into electronical pulses for processing. Examples are speedometer, electric meter,  water meter, thermometer etc.
2. Digital Computer: This operates on data representation in form of discrete values or digits (e.g 0,1,2,3,X,Y,Z,...). They handle numbers discretely and precisely rather than approximately. These types of computer are very common in use both at home and offices.
3. Hybrid Computer: This type of computers combines the features of both analogue and digital computer. They handle data in both discrete quantity and variable quantities. They are mostly found in industrial process for data acquisition and data processing purposes. In most cases, analogue signal generated from the analogue computer needs to be converted to  digital signal which has to be processed by the digital computer, hence, the need for Analogue-to - Digital Converter and Digital-to- Analogue Converter modulator/demodulator (Modem).

Classification by Size

Computer can also be classified by size. And these are as follows:

• Super Computers: The super computer are extraordinarily powerful computers and they are the largest and fastest computer system. They provide high level of accuracy, precision and speed for mathematical computations, meteorological, astronomical and oil exploration applications. In most of the Hollywood's movies, it is used for animation purposes. It is also helpful for forecasting weather reports worldwide. Examples are Cray-1, Cyber series, Fujistu, ETA-10 system. Most of these machines are not available for commercial use. It occupies a whole hall or theatre.
• Mainframe Computer: This is a system that has a very powerful Central Processing Unit (CPU) linked by cable to hundreds or thousands of terminals. This system is cable of accepting data simultaneously from all the terminals at the same time. This type of computers are very big and very expensive general-purpose computer with memory capacity more than 100 millions bytes and processing power of well above 10 Million Instructions Per Second (MIPS). Mainframe computers are used in large organizations such as bank, oil companies, big hospitals, airline reservations companies, examination bodies such as WAEC (west African Examination Council), JAMB (Joint Admission and Matriculation Board), etc. that have very large volumes of data to process which also need to be adequately secured. Examples include ICL 1900 and IBM 360/370 series, IBM 704 etc. It typically occupies a room or large space.
• Mini Computer: This type of computer share similar features with mainframe computers but it is smaller in physical size; generate lower heat, has less instruction set and is less expensive. Its requires the same conditions for its operation like mainframe computers. Such conditions are very cool environment because of the enormous heat being generated, raised or false floor, dust free environment, high-secured office accommodation. Examples of minicomputer are IBM AS/400, NCR Tower 32, DEC System, PDP 7 etc. This is the type of computer being used at the Computer Services and Information Technology (COMSIT) in the university of Ilorin, Nigeria.
• Microcomputer: This types of computers is much smaller in size compared to either mainframe or minicomputer. On these systems, various integrated circuits and elements of computer are replaced by a single integrated circuit called "chip". Microcomputer was first developed by companies like Apple Computers and later by IBM PC in 1981. It is also called Personal Computer (PC). Other types of computers based on size are palmtop and PDA (Personal Digital Assistant).

Classification by Generation

The industrial revolution during and after the 2nd World War was fully annexed by the stakeholders in information technology to fully actualize their dreams of having a very reliable computer, hence, the classification of computers into generations. There are five basic generations to which computer can be classified.

1. First Generation Computer: These were the early computers that were manufactured in 1940's. The first generation computer were characterized with the use of Vacuum tubes as its major components. These vacuum tubes generate enormous heat and consume much electricity. The first generation computer introduce the concept of stored programs. Exclusively, computer expert can program the computer only in machine language, which make it programmable. Examples are UNIVAC (UNIversalAutomatic Computer), ENIAC (Electronic Numerical Integrator and Calculator) etc.
2. Second Generation computer: These were the set of computers that succeeded the first generation computers. Their advent was in early 1950's and lasted until late 1950's. The components of computer were built around transistors which replace the vacuum tube in the first generation. The resultant effect of the transistors in replace of vacuum tube in reduction in size compared with first generation computers, less power consumption, generation of less heat and improved storage facility due to introduction of magnetic devices for storage medium. The overall effects are the improved reliability and introduction of symbolic languages for programming. Examples are ATLAS, IBM 1400 series (International business Machine), PDP I& II (Programmed Data Processor I& II) etc. 
3. Third Generation computer: This generation of computer succeeded the second generation computers. The advent of this generation was between early 1960's to late 1960's. Due to the technological advancement that had coupled into a single unit component. Hence, the major component that characterized the third generation computer is the integrated Circuitry (IC), which is a resultant effect of thousands of transistors combined into a single unit component. The integration of transistors into one components makes the computer smaller in size compare with first and second generation computers, faster machine, consume less power and generate less heat. The concept of multi-programming was introduced in this generation of computers. Programming was made easier by the use of high level languages. Examples are : IBM 360/370 series, ICL 1900 series (International Computers Limited) etc.
4. Fourth Generation computer: The emphasis in the first three generations of computers has been on the development of a computer system that is less expensive, more portable and highly reliable. The fourth generation computers were also developed having in mind  the above assertions. These generations of computers were built around Very Large-Scale Integrated Circuitry (VLSI) in which over ten thousands flip-flops were placed in a single silicon chip i.e. thousands of ICs were combined into a single chip. This period witnessed the era of microcomputer with the introduction of microprocessors as its major component. The system came into being in the early 1970's and still existence till date. Examples include: IBM, COMPAQ 2000 series, Dell series, Toshiba etc.
5. Fifth Generation computer: The development of the fifth generation computer started in the 1980's and classical researches are still going on in this generation of computers. Although, some of these machine are already in use, but a lot of work still need to be done to actualize the reasons for this generation of computers. The objective of this generation computer system is to build a computer machine that mimic the intelligence of human expert in a knowledge domain such as medicine, law, education, criminal investigation, etc. This objective is achieved through the implementation of Artificial Intelligence and Expert System development.

Classification by Purpose

There are two (2) classification to which computers are grouped, according to their usage or function. These are special purpose and general purpose computers.

1. Special Purpose Computer: This type of computer is specially developed to perform only one task. The system is highly efficient and economical but lacks flexibility. The program for the machine is built into the machine permanently. Some areas of usage include air traffic control system; military weapons control system, ship navigation system and industrial process controls.
2. General purpose computer: These computer have the ability to handle a wide variety of programs and to solve many problems such as payroll, numerical analysis, software development for accounting, inventory system etc. It makes use of stored program for switching from one application to another.

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