How Microprocessors Work
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Definition
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The microprocessor is the primary device that makes a personal computer work. It is a microscopic integrated circuit that has controllers and transistors on one piece of silicon. The microprocessor is also called the central processing unit (CPU), and it is the most expensive part of a personal computer. Microprocessors have been in production since the 1970s, and they continue to get faster and smaller. There are a large number of different types of microprocessor chips including the 6502, 8086/8 and RISC. Intel is the world's largest manufacturer of microprocessors, including the Pentium series of microprocessors.
Computation
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The arithmetic logic unit (ALU) allows a microprocessor, or CPU, to perform simple mathematical and logical functions. The ALU allows the CPU to perform simple addition and subtraction. Using addition and subtraction, the ALU can also perform multiplication and division. More advanced CPUs have ALUs that can perform advanced floating point calculations as well. The ALU can also perform logical calculations such as AND, OR, XOR and NOT. These calculations are all based on a simple binary system, where the ALU accepts an operation and one or two numbers that are either 1 or 0. The ALU can return the result of the logical operation, also a 1 or 0. The power of a CPU is its ability to complete these computations with the ALU unit very, very fast---billions of times in 1 second.
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Data
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The CPU also has the ability to store data and move that data from one memory location to another. This is done by the use of assembly language instructions that tell the CPU when and where to move and store data. These are very small memory locations, usually storing 32 pieces of information (all 1s or 0s). However, these locations can be accessed, stored and moved very quickly (again, billions of times in a second).
Instructions
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The instructions that a CPU microprocessor understands must be in assembly language. Any other programming language has a method that converts those instructions to assembly language. This is done with either an interpreter or a compiler. For example, if instructions are written in Visual Basic, the Visual Basic compiler will convert those instructions into assembly language so the CPU can understand those instructions. These instructions are then processed one at a time, in order, unless the instructions dictate that they skip a section and jump to another section of instructions. These instructions include one or more memory addresses and an operation so the CPU can perform the requested operation on the selected memory addresses.
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