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Considering all of the incredible things computers can do nowadays, one would think they have and use very complex components and systems. Not really. All comput- ers, when you get right down to it, are just switches. By “switch” we mean something that switches the current flow (amperage) off and on. When this switch is turned on, current flows through it. When the switch is turned off, current does not flow through it. It’s that simple, just like the switch that turns on and off the light in your bathroom. While still switches by definition, the switches a computer uses are a little different. For one thing, computer switches are very fast - so fast most can be turned on and off billions of times a second. Another is they switch tiny amounts of current. In a computer, it’s usually something like nano-amperes, with nano meaning “billionth” or “billionth” of an amp. A typical computer “switch” is diagrammed below: “D” Terminal = Drain “S” Terminal = Source “G” Terminal = Gate While it may look complex, it’s really quite simple. Here’s how it works: For the N-channel part, a voltage placed on the Gate terminal allows current to flow from the Drain to the Source terminal. In other words, the part goes from a high resistance to a low resistance, which allows current to flow. For the P-channel part, the Gate terminal is brought to ground (0 volts), allowing current to flow from the Source to the Drain terminal. These “switches” are used to “retain” voltages that create computer memory. Com- puter memory is nothing more than voltage or no-voltage states. If there is adequate voltage there it’s called a logic 1. If there is no voltage there it’s called a logic 0. There are several types of memory. Volatile memory is memory which is not retained after the power is removed and reestablished. Nonvolatile memory retains its electrical state even after the power is turned off. Re- gardless of the type of memory, the function of retaining voltage states is the same. Electronic parts often have thousands of these “switches”. They are cheap, fast, and reliable. They have to be or they would be of little use to us. So when someone complains about how complicated their computer is you can assure them deep down inside the computer, things are really quite simple. Britt Britt Storkson may be contacted via e-mail to michele@worldwidedrillingresource.com $$* " ) $ ' %, '* '- '! () %) " $ )" $ *' %' #%' $ %'# ) %$ + ( ) )$, ) ', "" ((% ) %$ %' ' - $ )*' - ' ! () $ *$ ' %, $ " (( %$( ' - ) $$ ' %" '( & * ) %$ %%' ' . ( The “Switch” that Changed the World by Britt Storkson Owner, P2FlowLLC 33 WorldWide Drilling Resource ® FEBRUARY 2016