Fuchsia supports two ISAs: arm64 and x86-64.
Fuchsia supports arm64 (also called AArch64) with no restrictions on supported microarchitectures.
Fuchsia supports x86-64 (also called IA32e or AMD64), but with some restrictions on supported microarchitectures.
For Intel CPUs, only Broadwell and later are actively supported and will have new features added for them. Additionally, we will accept patches to keep Nehalem and later booting.
AMD CPUs are not actively supported (in particular, we have no active testing on them), but we will accept patches to ensure correct booting on them.