Computer Processors Explained
Inside every computer, a tiny brain is at work. The computer's processor is responsible for performing calculations both simple and complex and is one of the core components of any computer system. While these devices have changed significantly over the last several decades, their function has essentially remained the same.
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History
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Before the advent of the modern computer processor, large computers such as ENIAC had to be rewired to perform different computations. They used vacuum tubes to complete this task, which could not be easily repurposed to another job and never on the fly. This led to a large amount of effort to make any change and restricted ENIAC and its cousins to running only a single program at a time.
Microprocessors
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Over the next few decades, the invention of the transistor and advances in technology allowed the processing power of ENIAC to be moved into a single chip. This design was much more efficient, and it allowed processing speeds that would have been unheard of only a few years earlier.
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Processing Steps
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All calculations that a processor performs are really constituted of small, simple steps. By designing computer processors this way, a single chip can be built to accommodate any type of request, making it possible for computers to develop complex programs. The steps that a processor takes, in order, are fetch an instruction, decode its meaning, execute the instruction, and write results back to some form of memory.
Performing Math
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All mathematical operations performed in a processor are passed through a single part of the processor called the Arithmetic Logic Unit (ALU). This small circuit contains enough logic to perform simple mathematical operations and return their results to the processor. By performing repeated simple operations such as addition, complex problems like finding square roots can be solved.
Multitasking
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Processors actually have no idea what task they are currently performing. Their entire job is to simply take an instruction, perform it, and write its result back into memory. In a process called task switching, operating systems take advantage of this fact to allow multitasking on computers. By asking processors to perform a different set of instructions every few milliseconds, operating systems create the illusion that more than one program is being run at a time.
Multicores
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The central part of a processor that actually performs instructions is called a core. In the past few years, the focus of technological development has been on increasing the number of cores available within a processor. Doing so allows a computer to transparently break up large problems and distribute them among the cores in the processor, decreasing the amount of time necessary to perform calculations. This has the effect of speeding up your computer, especially when using several programs.
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