Principles of CPU architecture – logic gates, MOSFETS and voltage

The underlying principles of all computer processors are the same. Fundamentally, they all take signals in the form of 0s and 1s (thus binary signals), manipulate them according to a set of instructions, and produce output in the form of 0s and 1s. The voltage on the line at the time a signal is sent determines whether the signal is a 0 or a 1. On a 3.3-volt system, an application of 3.3 volts means that it’s a 1, while an application of 0 volts means it’s a 0. Processors work by reacting to an input of 0s and 1s in specific ways and then returning an output based on the decision. The decision itself happens in a circuit called a logic gate, each of which requires at least one transistor, with the inputs and outputs arranged differently by different operations. The fact that today’s processors contain millions of transistors offers a clue as to how complex the logic system is. The processor’s logic gates work together to make decisions using Boolean logic, which is based on the algebraic system established by mathematician George Boole. The main Boolean operators are AND, OR, NOT, and NAND (not AND); many combinations of these are possible as well. An AND gate outputs a 1 only if both its inputs were 1s. An OR gate outputs a 1 if at least one of the inputs was a 1. And a NOT gate takes a single input and reverses it, outputting 1 if the input was 0 and vice versa. NAND gates are very popular, because they use only two transistors instead of the...

Pin It on Pinterest