The CPU is one of the most important components of your computer — after all, it’s the central processing unit that handles a large majority of the equations involved in running your computer and its software in the first place. You may not be aware, however, that a CPU can be based on a number of different architectures.
First, you might be wondering what a CPU architecture is in the first place. In simple terms, a CPU is only able to understand some very basic low-level commands on its own. In order for a CPU to be able to understand more advanced computer languages, like C++ or Visual Basic, those programming languages have to be compiled into low-level commands the CPU can understand. The CPU architecture has to be as compact and efficient as possible — that way CPUs can process commands quicker and more easily, and hence your computer can run faster.
There are two main computer architectures used in consumer devices today — ARM and x86. But what’s the difference between those architectures?
ARM architectures come in two different forms — ARM, which is 32-bit, and ARM64, which is 64-bit. ARM chips use the RISC architecture, which is also called Reduced Instruction Set Computer. What that means is that ARM’s instruction set is relatively simple, and most instructions can be executed in one single clock cycle.
Not only that, but ARM chips use the load-and-store model, which means that operations between data objects have to be loaded from the computer’s memory to the processor’s registers, after which the operation is performed and then stored back into the memory. That’s different from x86 processors, because the load-and-store information is built straight into the chip’s instructions — so fewer instructions are ultimately required.
Because ARM chips are simpler, there’s a smaller amount of silicon used, and a smaller amount of energy used — so ARM chips are great for energy efficiency.
x86 processors use a different architecture, called CISC, or Complex Instruction Set Computing. CISC instructions are generally more complex, and will often take multiple clock cycles to execute a single instruction. As mentioned, unlike RISC-based processors, CISC chips have built-in load-and-store instructions, so ultimately the instructions for loading data and storing it in memory are shorter. What that also means is that CISC processors require a little more hardware to decode and execute instructions, which in turn means less effort on the compiler.
x86 chips aren’t as good when it comes to energy consumption, but they, generally speaking, perform a little better than ARM chips.
Another important thing to note is that x86 processors have instructions to work directly with input and output — however ARM does not have those instructions, so extra hardware is required.
Both of the two architectures have their advantages and disadvantages, and it can often be hard to say which one is better-performing, however very generally speaking x86 outperforms ARM, and it has instructions to perform with IO. ARM, however, is better when it comes to power consumption — so it has its advantages too.