CPU architectures what's the difference and why it matters

Apple, AMD and Intel all take significantly different approaches to building CPUs. Darien Graham-Smith takes a closer look at today's varied processor designs

f you're buying a new computer, there are two main processor architectures to choose between.

Windows PCs are normally built on the x86 platform, used by Intel and AMD, while Apple's computers use the company's M1 and M2 processors, based on the ARM architecture. In this article, we explore the differences between their approaches, and what that means in practice.

Instruction sets

The x86 and ARM processor platforms do the same basic job, but they do it in different ways. Their internal logic is wired up in different arrangements, with different configurations of internal data registers and different sets of hard-coded instructions. At a fundamental level, they run programs in different ways and use different code.

Apple's M-series CPUs have been using a 5nm process since 2020

On the x86 platform, the internal structure and instruction set of the processor is ultimately based on that of the Intel 8008, an 8-bit CPU that debuted in 1972. In fact, machine code programs written for that chip can still be assembled and run on the latest processor from Intel or AMD.

Naturally, though, the hardware has evolved considerably since then. After the 8008 came the 8088, and then the 16-bit 8086, which powered the original IBM PC. In the 1980s this was followed by the 80186, 80286 and so forth – hence the “x86” moniker.

Through the generations, new features have been introduced to support multitasking and virtual memory; support has also been added for 32-bit and 64-bit operations, enabling computers to work efficiently with huge data sets and massive amounts of RAM. A series of extensions accelerated specific tasks such as graphics processing, virtualisation and data encryption.