From what I recall, the K12 core was essentially the same micro-architecture as Zen, but with ARM instruction decoders. There were some vague statements that th

From what I recall, the K12 core was essentially the same micro-architecture as Zen, but with ARM instruction decoders. There were some vague statements that the ISA allowed some optimizations compared to the x86 version, but we never got to see what that really means, since the K12 project was shelved to focus on x86. I wouldn't be surprised if AMD has been sitting on K12 and keeping it just updated enough so that they could revive it whenever the market becomes more interested in ARM servers.