CPU architectures what's the difference and why it matters

Apple, AMD, and Intel all take different approaches to building CPUs. Darien Graham-Smith explains why

- Darien Graham-Smith

If you’re considering buying a new computer, there are currently two main processor architectures to choose between. Windows PCs are normally built on the x86 platform, which is used by both Intel and AMD, while Apple’s computers use the company’s M1 and M2 processors, based on the ARM architecture.

The x86 and ARM processor platforms do the same basic job, but they do it in slightly 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.

Over the next few pages, we will explore the main differences between the approaches of these two different architectures, and what that means in practice.

Instruction sets

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 was launched in 1972. In fact, machine code programs written for that chip can still be assembled and run on the latest processors 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” name.