What is Computer?

A computer(Commonly Operated Machine particularly Used for Technical Education and Research) is a programmable electronic device that accepts raw data as input and processes it with a set of instructions (a program) to produce the result as output. It renders output just after performing mathematical and logical operations and can save the output for future use. It can process numerical as well as non-numerical calculations. The term "computer" is derived from the Latin word "computare" which means to calculate.

Block Daigram / Components of Computer

There are 5 main computer components that are given below:

CPU - Central Processing Unit
INPUT DEVICES - Input Devices like Keyboard, Mouse, Touchpad, etc.
OUTPUT DEVICES - Output Devices like Monitor, Printer, Speaker, etc.
PRIMARY MEMORY - Primary Memory like RAM, ROM, Flash, etc.
SECONDARY MEMORY - Secondary Memory like HDD, SSD, etc.

CONTROL UNIT

The Control Unit is the part of the computer that controls the flow of data between the input devices and the output devices. Control unit acts like the supervisor which determines the sequence in which computer programs and instructions are executed. It retrieves instructions from memory, decodes the instructions, interprets the instructions and understands the sequence of tasks to be performed accordingly. It further transmits the instructions to the other parts of the computer system to execute them. In short, the control unit determines the sequence of operations to execute the given instructions.

ARITHMETIC & LOGICAL UNIT

Arithmetic Logic Unit (ALU) performs arithmetic and logical operations. Arithmetic unit controls simple operations such as addition, subtraction, multiplication, division etc. The logical unit controls complex operations such as AND, OR, NOT, XOR, etc.

Primary Memory

Primary Memory cannot store vast amounts of data. Data stored in primary mermory is temporary and is lost when the computer is turned off. primary memory usually stores the input data and immediate results of the instructions. primary memory is also known as Volatile Memory or Main Memory. RAM is a type of primary memory.

Secondary Memory

Use of primary memory is not possible to store data permanently for future access. Therefore, there are some other options to store the data permanently for future use, which is known as non-volatile memory or Secondary Memory. Data stored in secondary memory is safe and can be accessed anytime. Hard Disk is a type of secondary memory.

Note: Primary memory is the only memory that is directly accessible to the CPU. Secondary memory is not directly accessible to the CPU. The data accessed from the secondary unit is first loaded into RAM and then further transferred to the Processing Unit. The use of different memory units depends entirely on the size of the data.

History of Computers

The first counting device was used by the primitive people. They used sticks, stones and bones as counting tools. As human mind and technology improved with time more computing devices were developed. Some of the popular computing devices starting with the first to recent ones are described below;

Abacus

The history of computer begins with the birth of abacus which is believed to be the first computer. It is said that Chinese invented Abacus around 4,000 years ago.

It was a wooden rack which has metal rods with beads mounted on them. The beads were moved by the abacus operator according to some rules to perform arithmetic calculations. Abacus is still used in some countries like China, Russia and Japan. An image of this tool is shown below;

Napier's Bones

It was a manually-operated calculating device which was invented by John Napier (1550-1617) of Merchiston. In this calculating tool, he used 9 different ivory strips or bones marked with numbers to multiply and divide. So, the tool became known as "Napier's Bones". It was also the first machine to use the decimal point.

Pascaline

Pascaline is also known as Arithmetic Machine or Adding Machine. It was invented between 1642 and 1644 by a French mathematician-philosopher Blaise Pascal. It is believed that it was the first mechanical and automatic calculator.

Stepped Reckoner or Leibniz wheel

It was developed by a German mathematician-philosopher Gottfried Wilhelm Leibniz in 1673. He improved Pascal's invention to develop this machine. It was a digital mechanical calculator which was called the stepped reckoner as instead of gears it was made of fluted drums. See the following image;

Difference Engine

In the early 1820s, it was designed by Charles Babbage who is known as "Father of Modern Computer". It was a mechanical computer which could perform simple calculations. It was a steam driven calculating machine designed to solve tables of numbers like logarithm tables.

Analytical Engine

This calculating machine was also developed by Charles Babbage in 1830. It was a mechanical computer that used punch-cards as input. It was capable of solving any mathematical problem and storing information as a permanent memory.

Tabulating Machine

It was invented in 1890, by Herman Hollerith, an American statistician. It was a mechanical tabulator based on punch cards. It could tabulate statistics and record or **sort data* or information. This machine was used in the 1890 U.S. Census. Hollerith also started the Hollerith?s Tabulating Machine Company which later became **International Business Machine (IBM) in 1924**.

Differential Analyzer

It was the first electronic computer introduced in the United States in 1930. It was an analog device invented by Vannevar Bush. This machine has vacuum tubes to switch electrical signals to perform calculations. It could do 25 calculations in few minutes.

Mark I

The next major changes in the history of computer began in 1937 when Howard Aiken planned to develop a machine that could perform calculations involving large numbers. In 1944, Mark I computer was built as a partnership between IBM and Harvard. It was the first programmable digital computer.

Generations of Computers

A generation of computers refers to the specific improvements in computer technology with time. In 1946, electronic pathways called circuits were developed to perform the counting. It replaced the gears and other mechanical parts used for counting in previous computing machines.

In each new generation, the circuits became smaller and more advanced than the previous generation circuits. There are five generations of computers which are described below;

1st Generation Computer (1940 - 1956)

The first generation (1946-1959) computers were slow, huge and expensive. In these computers, vacuum tubes were used as the basic components of CPU and memory. These computers were mainly depended on batch operating system and punch cards. Magnetic tape and paper tape were used as output and input devices in this generation. They could roughly perform 5000 additions or subtractions per second!

These computers were used during the Second World War to calculate the aim of ballistic weapons and decode messages.

Some of the popular first generation computers are;

ENIAC ( Electronic Numerical Integrator and Computer)
EDVAC ( Electronic Discrete Variable Automatic Computer)
UNIVACI( Universal Automatic Computer)
IBM-701
IBM-650

2nd Generation Computer (1957 - 1963)

Second-generation computers were built using transistors. Most of the development of transistors happened in Santa Clara Valley in the USA. And because transistors used silicon, this place was soon called Silicon Valley! Second-generation computers could perform roughly 5000 additions in a second but they were way more accurate!

In this generation, magnetic cores were used as the primary memory and magnetic disc and tapes were used as the secondary storage. Assembly language and programming languages like COBOL and FORTRAN, and Batch processing and multiprogramming operating systems were used in these computers.

Some of the popular second generation computers are;

IBM 1620
IBM 7094
CDC 1604
CDC 3600
UNIVAC 1108

3rd Generation Computers (1964 - 1971)

The third generation computers used integrated circuits (ICs) instead of transistors. A single IC can pack huge number of transistors which increased the power of a computer and reduced the cost. The computers also became more reliable, efficient and smaller in size. These generation computers used remote processing, time-sharing, multi programming as operating system. Also, the high-level programming languages like FORTRON-II TO IV, COBOL, PASCAL PL/1, ALGOL-68 were used in this generation.

Some of the popular third generation computers are;

IBM-360 series
Honeywell-6000 series
PDP(Personal Data Processor)
IBM-370/168
TDC-316

4th Generation Computers (1971 - 1980)

The fourth generation (1971-1980) computers used very large scale integrated (VLSI) circuits; a chip containing millions of transistors and other circuit elements. These chips made this generation computers more compact, powerful, fast and affordable. These generation computers used real time, time sharing and distributed operating system. The programming languages like C, C++, DBASE were also used in this generation.

Some of the popular fourth generation computers are;

DEC 10
STAR 1000
PDP 11
CRAY-1(Super Computer)
CRAY-X-MP(Super Computer)

5th Generation Computers (1980 - current day)

In fifth generation (1980-till date) computers, the VLSI technology was replaced with ULSI (Ultra Large Scale Integration). It made possible the production of microprocessor chips with ten million electronic components. This generation computers used parallel processing hardware and AI (Artificial Intelligence) software. The programming languages used in this generation were C, C++, Java, .Net, etc.

Some of the popular fifth generation computers are;

Desktop
Laptop
NoteBook
UltraBook
ChromeBook