Modern Day computers

Modern Day Computers – The Invention of the Transistor

The invention of the transistor or semiconductor was probably the most important development that lead to the personal computers amazing growth and what we know of as modern day computers. 

In 1947 the first transistor was invented by two engineers working for Bell Laboratories named John Bardeen and Walter Brittain. 

Also and only a few months after Bardeen and Brittain’s transistor William Shockley from Bell invented a junction transistor.  In 1956 all three together shared the Nobel Prize in Physics for their invention of the transistor.  What an amazement accomplishment it was.

The transistor ultimately replaced the vacuum tube as an electronic switch because it was so much smaller and less power hungry.  Let’s not forget computer systems built around the transistor were also smaller, faster, and way more efficient than vacuum tube designs. 

Modern Day Computers – The Makeup of the Transistor

Transistors are primarily composed from the two elements silicon and germanium.  Some impurities are also added and depending on which impurities and its electron content the material becomes what is called N-Type/negative, or P-Type/ positive.  Both N-Type and P-Type are conductors and so they allow electricity to flow in either direction.  If you join the two on the other hand a barrier in the middle is formed and electrical current flows only in one direction when the voltage is present in the correct polarity, hence the name semiconductors.

Transistors are made by placing two P and N junctions back to back and by squeezing a thin wafer of one type of semiconductor material between two wafers of the other type.  Wafers in the middle made from P-Type are called a NPN and those of N-Type are called PNP.

When discussing NPN transistors the N-Type semiconductor material on one side of the wafer is designated an emitter and it is most often connected to a negative electrical current.  The P-Type material in the middle is the base, and finally the N-Type material on the other side of the base is called the collector.

If you compare an NPN transistor to a vacuum tube triode the emitter is actually the equivalent of the cathode, the base is the same as the grid, and finally the collector is the tubes equivalent of the plate component.  Simply control the current at the base and it actually controls the flow of electrical current between the emitter and collector. Pretty sweet!

Long gone are the days of the tube as you can see, the transistor is simply way more efficient and it can be shrunk to microscopic proportions.  Today’s microprocessors such as the Core 2 Duo and others literally have millions of these microscopic switches we call transistors.  Pretty amazing!