I think one of the biggest milestones in the history of computers is the transistor. American physicists John Bardeen, Walter H. Brattain, and William Shockley invented the transistor in 1947. The first transistor was created at Bell Laboratories on December 16, 1947. "This was perhaps the most important electronics event of the 20th century, as it later made possible the integrated circuit and microprocessor that are the basis of modern electronics." (1946: Invention Of The Transistor.) .
Before the transistor, the only option to its current regulation and switching functions was the vacuum tube, which could only be made smaller to a certain extent, and wasted a lot of energy in the form of heat. The first transistor consisted of a plastic triangle suspended lightly above a geranium crystal which itself was sitting on a metal plate attached to a voltage source. A strip of gold was wrapped around the point of the triangle with a tiny gap cut into the gold at the precise point it came in contact with the germanium crystal. The germanium acted as a semiconductor so that a small electric current entering on one side of the gold strip came out the other side as a proportionately amplified current.
The reason transistors were better than a vacuum tube was its ability to be miniaturized. Vacuum tubes limited the growth of computers. Vacuum tubes were bulky, used a lot of energy, and were somewhat fragile and easy to overheat. Engineers knew they needed to find something different. .
In 1945, the vice-president of Bell Laboratories established a research group. The research team was led by William Shockley and included Walter Brattain, and John Shockley. "The team was talented and worked well together. After two years of frustrating but very exciting work, Bardeen and Brattain created an amplifying circuit using germanium. They called it the point-contact transistor. Its discovery was announced at a news conference, but received for the most part as a smart gadget the phone company had developed.