Apple could indeed fab a small memory controller chip, but I am not sure the M2 Ultra die has the interconnect to support such a thing? AMD makes this looks "ea

Apple could indeed fab a small memory controller chip, but I am not sure the M2 Ultra die has the interconnect to support such a thing? AMD makes this looks "easy," but it is not easy, and they built for Infinity Fabric from the start. As said below, the answer is CXL. Apple would be stupid not to support CXL devices on the M3 or M4, though I would not be surprised if they skip it