TOPIC ONE: INTRODUCTION TO COMPUTERS Sub-topic 1.2 Evolution and Origin of computers

SUBTOPIC 1.2: Evolution and Origin of Computers

The word Evolution comes from the Latin word, ‘ēvolvō’ which literally means; to ‘unroll’, or to ‘unfold’. 

Evolution of computers refers to the historical developments through which computers and technology have passed, from the time they started to exist in ancient forms to their current state.

Knowledge about the history/evolution of computers gives us a deeper understanding of the origin and the gradual Mechanical to Electro-mechanical to Electronic technological changes, which have brought about the kind of computers we see today, and helps us to predict how they will be in future.

  1. Origin of Computing (Counting and Calculating using devices)

The origin of computing started with the early man who used fingers, stones, sticks, marks on walls, sand, e.t.c.  The word ‘compute’ was derived from two Latin words; ‘com’, which means ‘together’ and ‘putare’, which may means ‘add, calculate, count, or estimate’.  Over the centuries, people have developed an amazing variety of data processing tools and techniques.

Examples of Ancient counting and calculating devices include  The abacus, Napier’s bones, the Slide rule.

i). The Abacus (3000 BC)

The beginning or foundation of computing devices is the abacus, which was developed in 3000 BC by Chinese (about 5000 years ago).  It was built out of wood and beads.  It has two decks. Each bead in the upper deck is equal to 5 units while each bead in the lower deck is equal to 1 unit. Only beads in the middle position are counted. The abacus helps people keep track of numbers as they do the computing. It is quick but has no storage capabilities.

The abacus is still in use today by schools and shopkeepers in Asia. Blind children are taught to use the abacus to perform calculations.

The abacus is an excellent substitute for teaching other base numbering systems, since it easily adapts itself to any base

ii). Napier’s bones (1617)

John Napier was a Scottish mathematician and inventor. Napier is famous for creating the decimal point. In 1617, the last year of his life, Napier invented a tool called “Napier’s Bones”.

Napier’s bones were multiplication tables written on strips of bones, ivory, silver, or wood. The invention was used for simplifying multiplication, division, and taking square roots and cube roots.

It had a set of rods, allowing computations up to 100,000,000.  The left (or “index”)rod is fixed to the case. It is numbered from 1 to 9. The movable rods are numbered at the top. The numbers down the rods show the product of the number at the top times the corresponding numbers on the index rod.

iii). William Ought red’s Slide rule

In 1622, William Oughtred an English mathematician created the slide rule which originally circular and was based on logarithms. It was the primary calculator for engineers throughout the 19th and early 20th centuries.

With a common accuracy of only three digits, the slide rule was not suited to situations where accuracy was needed such as in accounting. The slide rule is an analog device and it is still widely used.

It was primarily used for multiplication, and division and also for functions such as roots, logarithms and trigonometry but it was not normally used for addition and subtraction.

b) The Mechanical Computers era (1623 – 1945)

Before 1642, all computations were done by humans. Manual devices used then could just aid the users to keep track of numbers as they did the computing. In the Mechanical Era (Period) however, machines with gears work did the computations.

The mechanical computers are machines that are characterized with mechanical gears, wheels, moving parts, electro-mechanical relays, and dials and could use punched cards and tapes for data storage.

The Mechanical Computers era (1623 – 1945)

The popular mechanical developments of computers in this period include:

  • Blaise Pascal’s Calculator (1642),
  • Leibniz’s Stepped Reckoner (1694),
  • Jacquard’s Loom (1801), and
  • Charles Babbage’s Analytical & Difference Engine (1834).

This era also saw the development of the world’s first computer programmer Ada Byron Lovelace (1815-1852)

  1. Blaise Pascal’s Calculator (1642)

Pascal, Blaise (1623-62), was a French philosopher, mathematician and physicist.  In 1642, at the age of 18, he invented the first mechanical calculator to speed arithmetic calculations for his father, a tax official. He designed the machine to add and subtract two numbers directly and to perform multiplication and division through repeated addition or subtraction. Numbers were dialed in on the metal wheels on the front of the calculator. The solutions appear in the little windows along the top.

(ii) Leibniz’s Stepped Reckoner (1694)

The Stepped Reckoner was a digital mechanical calculator invented by German mathematician Gottfried Wilhelm Leibniz around 1672 and completed in 1694.

It was the first calculator that could perform all four arithmetic operations: addition, subtraction, multiplication and division. Its complex gear work, however, was a bit beyond the manufacturing technology of the time. Mechanical problems, in addition to design defects in the carry mechanism, prevented the machines from working reliably.

(iii) Jacquard’s Loom (1801)

In 1801, Joseph Marie Jacquard (1752-1834) of France made the first successful automatic draw loom by means of a series of instructions given to the threads by a punched card system. The loom could produce complex patterns and pictures in silk and other materials.

By 1812, the punched card device was attached to 18,000 looms in Lyons.  The Jacquard loom was a technological break- through.   J. M. Jacquard even received a pension from Napoléon for his invention

(iv) Charles Babbage’s Analytical & Difference Engine (1834)

The concept of today’s computers (Input – Process – Output) was first visualized by Charles Babbage in 1834 in England.  He is therefore regarded as the father of computers. His idea for the Analytical Engine consisted of 4 parts: an input device, a mill (processing unit), a storage device, and an output device.

It used punched-card system derived from the jacquard loom for input, processing and output. Variable punched cards transported numbers back and forth from the mill. It decided what operation to use, addition, subtraction, multiplication, or division.

The First Computer Programmer

Ada Byron Lovelace (1815-1852) was the world’s first computer programmer.   In 1842, Ada was asked to write a scientific interpretation of the Analytical Engine and its operations. These extensive writings on the Analytical Engine later became known as the first explanation of computer programming.  A computer language, Ada, was later named after her by the Ada Joint Program Office in 1964

(c)The Electro-mechanical Computers Era (1890 – 1946)

Before 1890, Electricity was not used by computers. As Electricity availability was becoming widespread, it was involved in the use of computational devices.

The popular developments of computers in the Electro- mechanical era include:

  • Hollerith’s tabulating machine (1890)
  • Howard Aiken’s Harvard Mark I (1944)
  • Program “debugging”

(i) Hollerith’s tabulating machine (1890)

Herman Hollerith (1860 –1929) was an American statistician who developed a mechanical tabulator based on punched cards to rapidly tabulate statistics from millions of pieces of data.  He decided to use punched cards to represent the data gathered for the USA population census of 1890, and to read and collate this data using an automatic machine.

Hollerith’s machine used a set of spring loaded wires suspended over the punched card reader. When the wires were pressed onto the card, punched holes allowed wires to complete electric circuits.  The cards were coded for age, state of residence, gender, and other information. The census results were “… finished months ahead of schedule and far under budget”.

Howard Aiken’s Harvard Mark I (1944)

While a professor of Physics at Harvard University, Howard Aiken, was supported by IBM to build an electro-mechanical computer which began computations for the U.S. Navy Bureau of Ships.  The computer was called the Automatic Sequence Controlled Calculator – (ASCC) by IBM but Aiken renamed it the Mark I

The First Computer Debugger

Dr. Grace Murray Hopper was a lady in the U.S. Navy Bureau of Ships, who worked with Howard Aiken from 1944 and used his machine for gunnery and ballistics calculation. One day, the program she was running gave incorrect results and, upon examination, a bug (moth) was found blocking one of the relays.  The bug was removed and the program performed to perfection.  Since then, a program error in a computer is known as a bug.

Debugging is a process of finding and correcting errors, in a computer program or a piece of electronic hardware.

Electronic era (1946 – Today) including The Computer Generations

Application of mechanical gears in Computers stopped in the Electro-mechanical era. Computer evolution since 1946 has been categorized into five generations. Each generation had a major characteristic development (commonly referred to as Hallmark) and distinct characteristics in terms of Physical setup, Technology, Software, and Set-backs of the computers.

Computer generations

Computer generations refers to the technological advancements and developments computers have passed through ever since they were discovered up to date

  1. The first generation (1940 – 1956): Vacuum Tubes

The first computer systems used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. These computers were very expensive to operate and in addition to using a great deal of electricity, the first computers generated a lot of heat, which was often the cause of malfunctions.

First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. It would take operators days or even weeks to set-up a new problem. Input was based on punched cards and paper tape, and output was displayed on printouts.

Characteristics of 1st Generation Computers


First generation computers were very large. Machines with hundreds of thousands of vacuum tubes were built, taking up space of several floors in big buildings. They weighed about 30 tons


  • They used punched cards and paper tape for input.
  • They used magnetic drums for memory.
  • The had memory size of approximately 2kilobytes of RAM .
  • They used binary number system.
  • Speed was about 10,000 instructions per second.


  • First generation computers used machine language, the lowest-level programming language understood by computers.

Setbacks with 1st generation

  • They broke down frequently (Required standby technicians)
  • Needed very many people to operate due to their huge size.
  • High level of training was required before use
  • They produced a lot of heat and burned out.
  • They consumed a lot of power/electricity
  • They produced a lot of noise.
  • They had limited primary memory, and so they were very slow.
  • They were very expensive to buy, setup and maintain.
  • They were not portable.
  • Manual assembly of individual components into one functioning unit required.
  • They required Air conditioning required

Examples of first generation computers:

  • ENIAC – Electronic Numerical Integrator and Computer (1946)  was the first electronic digital computer. It had over 18,000 vacuum tubes.
  • EDVAC – Electronic Discrete Variable Automatic computer (1947) was built for the U.S. Army’s Ballistics Research Laboratory
  • The UNIVAC (1951) (UNIVersal Automatic Computer) was the first general-purpose electronic digital computer designed for commercial use.

Other examples of First Generation Computers

Manchester BabyManchester Mark 1Farranti Mark 1IBM 702IBM 650TAC (Japan)   UNIVAC IWhirlwindIBM 701IBM NORCNICKOLASUNIVAC 1101BESM-1 (USSR)
  • The second generation (1958 – 1964): Transistors

A transistor is a semiconductor device used to amplify and switch electronic signals. It is made of a solid piece of semiconductor material. The invention of the transistor replaced the vacuum tube and paved  the way for smaller and cheaper computers.

Characteristics of 2st Generation Computers


  • The computers reduced in size as compared to first generation computers, and could now fit in one room.
  •  A typical second-generation computer contained 10,000 transistors hand soldered and connected by wires.
  • They still used punched cards for input and printouts for output
  •  Memory size expanded to approximately 32kilobytes
  • The computers increased in processing speed and reliability – Speed was about 30,000 instructions per second
  • Transistors consumed less power as compared to vacuum tubes
  • Memory moved from a magnetic drum to magnetic core technology, in which Hard disk storage was now available.


  • Second generation computers used assembly and high level programming languages such as FORTRAN (FORmula TRANslator) which allowed programmers to specify instructions in words.

Setbacks of 2nd Generation Computers

  • They produced less noise but their cost was still very expensive.
  • High level of training was required before use.
  • Transistors gave much heat that could damage other components.
  • Commercial production was difficult and costly.
  • The computers could still run only one application program at a time (Multi-tasking was not possible)
  • Air-conditioning was required.
  • Manual assembly of individual components into a functioning unit was required.

Examples of second generation computers:

  • IBM 305 RAMAC.(1956), was the first commercial computer that used a moving head hard disk drive (magnetic disk storage) for secondary storage. RAMAC stood for “Random Access Method of Accounting and Control”.
  • The IBM 1401, – was a variable word length decimal computer that was announced by IBM on October 5, 1959
  • The CDC 6600 was a mainframe computer from Control Data Corporation, first delivered in 1964. It remained the world’s fastest computer from 1964–1965.

  • The third generation (1965 – 1970): Integrated Circuits

Integrated Circuits: An integrated circuit (IC) was just a combination of thousands of transistors and tiny wires onto a small “chip” made of semi-conductor material such as silicon.

Characteristics of third generation (1965 – 1970)

  • The computers extremely reduced in size due to fabrication of various circuit elements in a single chip.
  • As a result, the computer could now fit onto a desk and the monitor became the largest visible part of the computer. 
  • For the first time, Electronic computers became accessible to a mass audience because they became cheaper.
  • The keyboards and monitors replaced punched cards for input and output.
  • Magnetic hard disks were developed for storage purposes
  • Memory size expanded to approximately 2 megabytes of RAM
  • The computers became more reliable because of elimination of soldered joints and need for fewer inter-connections.
  • Speed increased to 5 million instructions per second
  • Integrated Circuits consumed a lower electric power.
  • The noise produced by the computers reduced drastically.


  • Simple programming languages like BASIC were introduced.
  • Multi-tasking was now possible. (Users interfaced with an operating system which could run different applications at the same time.)

Setbacks of 3rd Generation Computers

  • Highly sophisticated technology required for the manufacture of IC chips.
  • They required Air-conditioning in many cases due to the heat produced.
  • If any component in an IC fails, the whole IC has to be replaced by a new one.
  • Operations were at a low voltage because ICs function at fairly low voltage.
  • Quite delicate in handling as these cannot withstand rough handling or excessive heat

Examples of third generation computers:

Popular developments in the third generation include:

  • The PDP-8 was the first commercially successful minicomputer. It sold more than 50,000 systems for $18,000.
  • The HP-2115  which was made by Hewlett-Packard (HP)
  • Fast minicomputers such as IBM 360 series and ICL 19000 series
  • IBM-360 series
  • Honeywell-6000 series
  • PDP (Personal Data Processor)
  • IBM-370/168
  • TDC-316

Another very good development that came up in this generation (1969) was The Advanced Research Projects Agency Network (ARPANET), the world’s first operational packet switching network .The ARPANET is the core network of a set that came to become the global Internet.  The network was created by a small research team at the United States Department of Defense.

  • The fourth generation (1971 – to date): Microprocessors.

Microprocessors are VLSI devices. Very-Large-Scale Integration (VLSI) is the process of creating integrated circuits by combining thousands of transistors into a single chip. The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were rebuilt onto a single silicon chip.  Invention of the microprocessor was made by a team at Intel Corporation.

Characteristics of fourth Generation Computers

  • The physical size of computers kept on reducing generation to generation.
  • With the development of micro-chips, what in the first generation filled an entire floor could now fit in the palm of the hand.
  • The fourth generation computers saw the development of the mouse and handheld input devices.
  • The Fourth generation computers were more powerful, they could be linked together to form networks.
  • A vast variety of Storage memory media used such as Floppy disks (1971),Optical Compact Discs(1982), USB flash drive disks(2000), etc.
  • Memory size progressively expanded up to more than 8 Gigabytes of RAM
  • The computers became very reliable.
    i.e. Computers can work for a long time
    without breaking down.


  • Operating systems based on the Graphical User Interface (GUI) were developed.
  • A GUI is a user Interface in which visual images such as icons and buttons are used to issue commands.
  • Microsoft Windows 1.0 was released by Bill Gates’ Microsoft Corporation on November 20, 1985

Setbacks of 4th Generation Computers

  • Highly sophisticated technology required for the manufacture of VLSI chips.
  • In a microprocessor chip, the various components are part of a small semi-conductor chip and the individual component or components cannot be removed or replaced, therefore, if any component in a microprocessor fails, the whole microprocessor has to be replaced by a new one.
  • Operations at low voltage as microprocessors function at fairly low voltage.
  • Quite delicate in handling as these cannot withstand rough handling or excessive heat

Examples of 4th Generation Computers

  • The Xerox Alto (1973) was the first computer to use a GUI.
  • The IBM 5100, portable computer that appeared in September 1975.
  • The Apple Macintosh (1984 ), was a mouse-driven computer at a much cheaper price.
  • The fifth generation (Today to future): Artificial Intelligence and Robotics.

Artificial intelligence (AI) is the ability of machines to have human capabilities, such as the five senses (to see, hear, feel, taste, smell), plus, understanding, communication, reasoning, learning, learning from past experiences, planning, and problem solving.  In future, computers are to be applicable in almost every imaginable place at home, office, factory, church, etc.

Characteristics of fifth generation computers

  • Physical setup:     The physical size of computers in this generation can be customized to any shape of interest – be it as small as a pen or in the shape of a human being.
  • The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

The fifth generation technology

  • There is use of coordinated parallel processing; where computers have many microprocessors being used side by side.
  • We shall see the development of many gadgets like remote control and optical input devices.
  • Secondary Storage Hard disk drives which can store Terabytes of Data. 
  • RAM will continue to increase  to 8GB, 16GB, 32GB, 64GB,128GB e.t.c.
  • The computers to become 99%  reliable.
  • More development of Notebook and Mobile computers which can store power for a long time, hence becoming too mobile.
  • More networking containing millions of interconnected 4th Generation computers.


Fifth-generation programming languages (5GLs) will be used.

  • 5GLs are based around solving problems using controls given to the program, rather than using an procedure written by a programmer,
  • They contain visual tools to help develop the programs. Visual Basic is an example of a 5GL
  • There will be a wide variety of computer Operating Systems and Application programs designed to solve specific tasks in a user-friendly manner.
  • Molecular computers expected, Composed of millions of DNA (Deoxyribo Nucleic Acid ) strands in plastic tubes.
  • Information-processing tools-such as enzymes and proofreading mechanisms are going to be taken in large numbers of DNA molecules and used as biological computer processors.
  • Diligent Robots will be highly used in many areas such as factories where repetitive tasks are done.
  • Computers to have Quantum computation and molecular and nanotechnology.

The fifth generation setbacks

  • Computer Obsession and addiction is seriously spoiling the writing and thinking abilities of human beings.
  • Computer Crime such as hacking and online theft is on the rise due to misuse of 5th Generation computer technology.
  • Robotics in the fifth generation will cause unemployment as machines take on the jobs people could do.

Examples of fifth generation computers:

  • TOSY Ping Pong Playing Robot (2007) is a humanoid robot designed to play table tennis against a human being.
  • Hospital Robots are becoming more useful to hospital staff; from supporting surgeons to paying bedside visits to patients.
  • The iPad (2010) is a tablet computer designed and marketed by Apple Inc., with a flat touch screen. It is primarily operated by touching the screen rather than using a physical keyboard

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