Computer Studies Notes

Computing Devices (20th Century To Date)


Generation of ComputersYear of DevelopmentThe Technology (input, control, design)CharacteristicsSoftware InstructionStorage Capacity
First1940 – 1950 e.g. edsac,Univa, edvac IBM 350Vacuum tubeGigantic ,Low speeding milliseconds(1/1000th of a seconds), high energy productionMachine languageSmall internal memory and internal storage of magnetic drum and delay lines.
Second1950 – 1960 e.g. The  IBM 605, Honeywell National Cash Register(NCR 304)TransistorLess heat generation,High level and assemblerCore storage
Third1960 – 1970 e.g. IBM 360, IBM 370 systems100-1000 chipsIntroduction of Integrated circuit(IC),use of operating system, communication cable and reduction in the cost of storage.Multi programming facilitiesinternal
Fourth1970 – 1980  e.g. IBM PS/2, Computers that used Intel (80286,80386) microprocessor1000-106 chipsLSIIntroduction of Non-procedural languageFlexible, internal and external and very large, network facilities
Five1980 – 1990  e.g Compaq, Dell, Toshiba, HP106 chipsArtificial intelligent(AI),speech production, expert systemIntroduction of object Oriented programming language(OOP)Small but powerful network



The first generation computers were developed between 1940s and 1950s.  Computers of that generation were characterized by:

1.         They used vacuum tubes.

2.         They were very large and expensive.

3.         They were very bulky.

4.         They had a low retentive memory

5.         They generated a lot of heat due to the use of vacuum tubes.

6.         They had reliability problem.

Examples of first generation computers are: ENIAC (Electronic Numerical Integrator and Calculator), EDVAC (Electronic Discreet Variable Automatic Computer), EDSAC (Electronic Delayed Storage Automatic Computer) and IBM 650.


Second generation computers were developed between 1950s and 1960s. In this generation, transistors were used instead of vacuum tubes.  Second generation computers utilized primary discrete TRANSISTORS.  They had limited capability but were more advanced than the first generation computers.

The following could be noted of second generation computers.

1.         They were more reliable than first generation.

2.         They could perform calculations.

3.         They had a more efficient storage facility.

4.         They generated lesser heat when compared with first generation computers.

Examples of this generation are: NCR 304 (National Cash Register 304) and IBM 605.


Third generation computers were developed between 1960s and 1970s. In this generation, Integrated circuits were used in place of vacuum tubes and transistors. Integrated circuits (IC) are produced as a single chip containing dozens of components fused together in a single process. In this generation, SSI (Small Scale Integration) and MSI (Medium Scale Integration) were used. In SSI, components in tens were fused as a single unit on a chip and in the MSI, components in hundreds are fused as a single unit on a chip.

The following can be noted in third generation computers:

1.         Faster input and output.

2.         Increased storage capability.

3.         Increased process capability.

4.         Ability to display pictures and musical sound.

Examples of third generation computers are IBM360 and IBM370.


  1. State four characteristics of the first generation computer.
  2. Write the full meaning of the following; i. ENIAC               ii. EDVAC      iii. EDSAC


Fourth generation computers appeared between 1970s and 1980s. In this generation, Large Scale Integrated (LSI) technique was used in the integrated circuits. In LSI, more than hundred components were placed on a single chip. This generation of computers brought about the development of microprocessors. The computers produced at this period were of a higher capability in terms of speed, storage and of superior performance over their counterparts of the third generation. Examples are: IBM PS/2, and computers that used Intel (80282, 80386) microprocessors.


  1. State the features of the 4th generation computer.
  2. Write down the full meaning of LSI


These generations of computers appeared between 1980s and 1990s. The technique used in the integrated circuits of these computers is Very Large Scale Integration, VLSI. Artificial Intelligence (AI), speech processing, pattern recognition and Expert System (ES) are characteristics of these computers. Artificial Intelligence is the ability of the computer to exhibit intelligence behavior like humans, while Expert System is the ability of the computer to make decisions and judgments like an expert in a particular field of profession.


We have learnt that the first generation computers used vacuum tubes, second generation used transistor while the third generation computers used integrated circuits. We also  learnt the features of the fourth and fifth generations of computers i.e. the fourth generation used Very Large Scale Integration (VLSI) and ARTIFICAL INTELLIGENCE (AI).


1.         What are Artificial Intelligence and Expert system?

2.         What are the technologies behind each of the generations of computer?

3.         State two features of first generation of computers.

4.         What is the technology behind Second and Third generation of computers.

Reading Assignment: Computer Studies for Junior Secondary Education JS1 by HiiT Plc. Page 30 – 33, Chapter 6.



1.         Which of these is not an example of first generation computers? (a) ENIAC (b) UNIVAC

           (c) EDVAC (d) IBM 360

2.         The first generation used …………… (a) IC  (b) SSI  (c) Transistor (d) vacuum tubes

3.         The second generation used ………..  (a) Vacuum tubes (b) MSI (c) IC (d) Transistors

4.         The third generation used …………..  (a) SSI (b) Transistor    (c) Vacuum tubes (d) ICs

5.         IC means ………….(a) Integrated Circle   (b) International Class  (c) In Charge

(d) Integrated Circuit


1.         State two features of first generation computers.

2.         What is the technology behind Second and Fifth generation of computers.

3.         Give the full meaning of the following acronyms:

(i)         AS

            (ii)        VLSI

            (iii)       SSI

            (iv)       LSI

            (v)        AI

4.         Mention the characteristics of 5th generation computers.

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