Generations of Computers

Why Computers Are Grouped Into Generations

Computers have developed enormously since they were first built, and this development is commonly described in five generations, each marked by a major change in the main electronic technology (the "switching" component) used to build the machine. With each generation, computers became smaller, faster, cheaper, more reliable, and easier to use.

First Generation (roughly 1940s–1950s) — Vacuum Tubes

The earliest electronic computers used vacuum tubes as their switching devices. These machines were enormous (often filling a whole room), consumed a great deal of electricity, generated a lot of heat, and broke down frequently. They were very expensive, had very limited memory, and were programmed in difficult machine language. Despite these drawbacks, they proved that general-purpose electronic computing was possible.

Second Generation (roughly late 1950s–early 1960s) — Transistors

The invention of the transistor replaced the bulky vacuum tube. Transistors were far smaller, generated less heat, used less power, and were more reliable and faster. Computers of this generation were smaller and more affordable, and programming became a little easier with the use of early high-level languages.

Third Generation (roughly mid 1960s–1970s) — Integrated Circuits (ICs)

Many transistors were combined onto a single small chip called an integrated circuit (IC). This made computers still smaller, much faster, more reliable, and cheaper. Operating systems and keyboards/monitors came into wider use, making computers easier to operate and allowing more than one program to run.

Fourth Generation (roughly 1970s–present) — Microprocessors

Advances in circuit design allowed the entire central processing unit to be placed on a single chip — the microprocessor. This made possible the personal computer (PC), small and cheap enough for an individual, a home, or a small business to own. Graphical user interfaces, networks, and the internet spread widely during this generation, bringing computing to ordinary people.

Fifth Generation (present and emerging) — Artificial Intelligence

The fifth generation is focused on artificial intelligence (AI) and very high levels of processing power, aiming for computers that can learn, reason, understand natural (human) language, and respond intelligently. Technologies associated with this generation include AI-based systems, voice assistants, robotics, and advanced parallel processing.

The Generations at a Glance