I know the cool thing is to hate on Apple for being Apple, but they have actually done a solid job with their transitions between instruction set architectures.

Ultimately, software developers and end users are forced to use the newer architecture, yes. But credit where credit is due, Apple chose to take the path of providing both hardware and software level facilities to make the transitions as seamless as possible over years-long timespans. They could have simply refused to support older architectures to force a migration down our throats, and indoctrinated fanboys would have opened their wallets anyway.

What they actually did was create compatibility layers, a multi-architecture executable file format, and binary translation frameworks built into the operating system. I fucking despise them for creating a walled-garden ecosystem and cult around their products, but I genuinely have to respect them for Rosetta and Rosetta 2. Developing a binary translation layer is a whole different beast than high-level emulation, and it’s significantly more difficult to pull off correctly. The fact that they managed to do it twice, and do it damn-near seamlessly is impressive. Rosetta 2 even supports translating just-in-time compiled code, which is a huge pain point for that kind of thing.

If you follow the history of the Mac, it went through a number of major architecture transitions from 680x0 -> PowerPC -> Intel -> ARM. Each time, Apple supplied a decent emulator to support applications during the transition.

From a developer perspective, these were huge upheavals that came with a lot of drama but also offered some opportunities. The latter came from the fact that the bar was in some way set higher on the new platform and you could count on any code you compiled for it supporting certain base features. Every PowerPC, for example, had hardware floating-point. Before that, some CPUs did, some didn’t. The Intel transition happened at the time when dual core had become standard and SIMD had become serviceable (with SSE2). The ARM transition has set the bar at 64-bit architecture for every CPU (since Apple had earlier dumped 32-bit on the iPhone side).

Windows/Intel has developed in a more evolutionary than revolutionary manner, which is easy to see if you look, for example, at all the legacy cruft in the Intel ISA. It’s a sad sight. Supporting all that makes instruction decoding a nightmare. In theory, Intel/AMD could reinvent a new sleeker ISA if they could get Microsoft to commit to supplying a performant emulator for the old one? But I’m not holding my breath.