They always used microcode: https://www.righto.com/2022/11/how-8086-processors-microcode-engine.html https://www.righto.com/2022/11/how-8086-processors-microcod

They always used microcode: https://www.righto.com/2022/11/how-8086-processors-microcode-engine.html https://www.righto.com/2022/11/how-8086-processors-microcode... I'm not sure when Intel started supporting microcode updates but I think it was much later.