1. A memory apparatus for use in a data system, the memory apparatus comprising: a plurality of physical memory circuits having a physical attribute; an interface circuit coupled to communicate with the physical memory circuits, and couplable to communicate with the data system, the interface circuit including, means for simulating a simulated memory circuit having a simulated attribute which is different than the physical attribute of the physical memory circuits, and for providing to the data system an interface to the simulated memory circuit including the simulated attribute, and means for controlling refreshing of the physical memory circuits.