Second-Generation Computers

In the late 1950s, the transistor replaced vacuum tubes in the computer. A transistor could conduct electricity more quickly and efficiently than a vacuum tube. It was more reliable, too. Vacuum tubes often "burned out" and needed to be replaced. Transistors rarely needed to be replaced. A transistor was also much smaller than a vacuum tube, and it did not get hot.

When companies started building computers with transistors instead of vacuum tubes, the computers became smaller. They also solved problems ten times faster than first-generation computers.

It is difficult to give credit to any one person for building a second-generation computer. These computers were so complex that it took many people with many different skills to design all the computer parts. Several large companies built these second-generation computers. Some were for their own use. Some were sold to other companies.

Third-Generation Computers

In 1964, tiny integrated circuits were developed to take the place of transistors. These tiny circuits were even faster and more reliable than transistors. Integrated circuits, or IC's, were very small. They took up very little space.

First- and second-generation computers were large machines. They stood on the floor and occupied a lot of space. But the third-generation computers were much smaller. Some could even sit on top of a table. Also, they could operate 100 times faster than second-generation computers (1000 times faster than first-generation computers!)

Integrated circuits were mass-produced at a low cost. So, as more computers were built with integrated circuits, the price of computers dropped lower and lower. Third-generation computers were inexpensive enough and small enough to be bought by thousands of companies around the world.

Fourth-Generation Computers

In the mid-1970s, scientists developed a method of putting thousands of integrated circuits on one tiny silicon chip. The chip itself is so small that it can fit through the eye of a needle. It is difficult to imagine so many circuits on such a tiny surface. It takes many delicate instruments and special scientific techniques to create this "miracle" chip, called an integrated circuit chip.

Integrated circuit chips, or ICCs, are smaller and less expensive than the integrated circuits used in third-generation computers. So, the fourth-generation of computers are even smaller and less expensive than the third-generation computers. Computers built with these chips can perform over 10 million calculations in one second. They are 10 times faster than third-generation computers. (That's 1000 times faster than second-generation computers and 10,000 times faster than first-generation computers!)

As you can see, each generation of computers used a new invention to conduct the electricity through the computer. As the new electrical devices got smaller, the computers got smaller. They became more powerful than the earlier, large computers. They also became less expensive, which enabled small companies, schools, and people to buy their own computers.