Eli5: what is inside a cpu, and how does it perform thousands of calculations a second?
In: Technology
Transistors are a 3 terminal semiconductor device in which the current in the third terminal can be controlled by the voltage across the other 2. CPUs uses this property in a creative way with logic gates. A logic gate is an arrangement of transistors in which (depending on the function of the gate) will output either a high (5V) or a low (0V), this is the 1s and 0s people think with digital computers. Logic gates can be arranged together to perform binary operations like addition or subtraction as some basic ones. These logic gates are what are arranged in the cpu, and they are incredibly small nowadays. Computers followed Moore’s law, which states that every two years the number of transistors in an integrated circuit doubles. This is how computers have gotten so much more advanced since their early days.
As far as the billions of computations per second, digital circuits have a ‘clock’ signal that controls when operations occur inside the logic gate circuits (usually on the rising or falling edge). This can be VERY fast. The main reason that the transistor is one of the biggest inventions in human history, is because before transistors any switching had to be done mechanically by physically breaking the circuit. Since they could now switch things electronically with changing voltages around the transistor, the speed of switching was increased by several orders of magnitude.
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