History of Computer – SS1 Data Processing Lesson Note (First Term)

Computers are grouped into five generations according to the main technology used to build them. First-generation computers used vacuum tubes. Second-generation computers used transistors. Third-generation computers used integrated circuits. Fourth-generation computers used large scale and very large scale integration. Fifth-generation computers are built around artificial intelligence.

Behavioural objectives

By the end of the lesson, students should be able to:

1. Name the five generations of computers.
2. State the main technology used in each generation.
3. List the features of first-, second- and third-generation computers.
4. Describe fourth- and fifth-generation computers.

What are the generations of computers?

First generation

Electronic machines which were distinct from mechanical computers evolved about 1945. UNIVAC is a good example of this generation of computers.

Computers of this generation were characterised by the following:

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.

Second generation

Second-generation computers replaced vacuum tubes with discrete transistors. They had limited capability but were more advanced than the first-generation computers.

Features include:

1. They were more reliable than the first generation.
2. They could perform calculations.
3. They had a more efficient storage facility.
4. They generated less heat than first-generation computers.

Third generation

Third-generation computers used Integrated Circuit (IC) technology and Small Scale Integration (SSI). They had more sophisticated software capabilities, such as multi-programming, multi-processing and operating systems as resource managers.

The following can be noted in third-generation computers:

1. Faster input and output.
2. Increased storage capability.
3. Increased processing capability.
4. Ability to display pictures and musical sound.

Fourth generation

Fourth-generation computers appeared in about 1975. The technologies that characterised these machines were Large Scale Integration (LSI) and Very Large Scale Integration (VLSI). The computers produced during this period had higher speed and storage capacity, and better performance, than those of the third generation.

Fifth generation

This generation of computers makes use of Artificial Intelligence (AI). Computers of this category were built around the following aims:

• To build supercomputers, that is, computers which could operate in the range of 10 billion instructions per second.
• To give computers capacities like sight and hearing, and the capability to simulate human thought, for example robots.

Evaluation

1. Name one example of a first-generation computer.
2. State three characteristics of first-generation computers.
3. Which technology marked the third generation of computers?
4. Which generation of computers makes use of artificial intelligence?

Assignment

1. The first generation used …… as its circuitry.
2. List four features of second-generation computers.
3. State two features of third-generation computers.
4. VLSI means ……….