@kenshirriff

Is this really microcode, or just assembly code?

I recall learning in 2001 that the AMD K8 internally translated opcodes to microcode, but the Wikipedia page isn't clear about which x86 device was first to implement it.

https://en.wikipedia.org/wiki/Microcode

"Earlier x86 processors are fully microcoded; starting with the Intel 80486, less complicated instructions are implemented directly in hardware. x86 processors implemented patchable microcode (patch by BIOS or operating system) since Intel P6 microarchitecture and AMD K7 microarchitecture."