Introduction to CPUs

[Daniel]

The CPU (Central Processing unit) is the heart of a computer. It is responsible for executing instructions sent from program(s). CPUs function a very particular way; first, they fetch instructions from the system memory. Then the instructions are decoded into commands by the control unit located inside the CPU. Next the commands are executed inside the ALU (Arithmetic Logic Unit - Look below for more information). Finally, it stores the results back into the system memory.

    There are two types of CPUs, 32-bit and 64-bit. The difference between the two is that the 32-bit CPUs can only handle a maximum of 4GB's of ram in a system while the 64-bit version can handle 16.8 million terabytes. Having that much ram is theoretical and impossible, it's simply the maximum amount of ram 64-bit can support.

    CPUs over the years have continuously grown and advanced, and the clock speed of them is no exception. The clock speed of a CPU is how many operations per second it can perform. A modern CPU can do about 200,000,000 (2Ghz) operations/instructions per second.

     Back in the day there used to only be individual CPU cores, however the most current processors combine two or more cores. This allows them to chew through multiple instructions at once, which in turn means you can run more programs smoothly as once. Of course, you can multitask on a single core CPU, but this is not truly simultaneous processing. Modern applications, can be divided into multiple threads, which can cut down processing times by 1/2, 1/4, 1/8, depending on your CPU. These can prove incredibly helpful when rendering a video, or encoding /encrypting. 

     Hyper-Threading (*Only certain Intel CPUs contain this* - Check below for more information) is used to gain addition processing power. Each core in a Hyper-Threaded CPU appears to the operating system as two virtual cores. If you were to look at this in reality, the single core can only process a single instruction at once, but it has two sets of registers. Because of this feature, it has the ability to switch back and forth between two threads very efficiently. In most situations it can give performance boosts up to 30%! Take this with a grain of salt because not all programs utilize the abilities of hyper-threading, and some tasks are even slower because of hyper-threading . Nonetheless this is a great feature if your CPU has it.

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    The ALU is a part of the CPU that performs all arithmetic computations such as, addition, subtraction, multiplication, and division. The ALU is the fundamental building block of the CPU. Modern CPUs have very complex ALUs, and some even contain more than one. The ALU has direct input and output to the following: Processor controller, system memory, and input/output devices.

     To check if your CPU contains hyper-threading (Windows Only), click the start button to open the start menu, (Or go to the far right in windows 8.1) and type in "System Information". Once here, you'll see a row labeled as "Processor", Type the name of the processor into google and click on the link that goes to Intel's website. Once here scroll down to "Advanced Technologies" and look next to "Intel Hyper-Threading Technology". *****NOTE THIS ONLY APPLIES TO INTEL CPUs*****

[Shadow19]

Nice explanation of CPU's and the difference between bit architectures.