– Transistors and their connection to logic gates.
In: Engineering
A logic gate is a theoretical construct that takes two (usually) binary inputs and outputs one binary output. So, for example, an AND gate outputs yes/TRUE/1/yay!/whatever when both inputs are yes/TRUE/1/yay!/whatever and no/FALSE/0/nope!/whatever otherwise.
You use logic gates to do binary arithmetic and logic operations, which are fundamental to modern computing.
*A* way to implement a logic gate in hardware is with an electric switch. In that case, the binary states are “high voltage” and “no voltage” or, less commonly, “current” and “no current”, or “open” and “closed” if you talk about the switch circuit itself. You can do this with any switch…a common household light switch, a relay, a vacuum tube, or…a transistor. A transistor, in the logic gate context, is just a very small, very fast, electronically controlled electric switch.
The first big jump in computing came when we went to electrically switched switches, rather than mechanically switched switches (from relays to vacuum tubes) because now there’s no moving parts and you can go a *lot* faster. Then we got another big jump with transistors because they can be manufactured from semiconductors and produced in incredibly small and integrated packages in one shot, rather than wiring up a bunch of individual components. This brought the cost per switch so low that “everybody” could carry a few billion transistors around in the their pocket for cheap.
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