Patent ID: 7624225

Claim:
A memory interface device adapted for use in a memory system, the memory interface device comprising: an interface to one or more ranks of memory devices, each memory device including one or more types of mode registers; an interface to a memory bus for receiving commands from a memory controller, the commands including a mode register set command specifying a new mode register setting for one or more ranks of memory devices and a mode register type; and a mode register shadow module to capture settings applied to the mode registers, the module including a shadow register for each type of mode register and a shadow log for each type of mode register, and mode register shadow logic to detect a mode register set command, to store the new mode register setting in the shadow register corresponding to the specified mode register type, and to set one or more bits in the shadow log corresponding to the specified mode register type to indicate which of the ranks of memory devices have been programmed with the new mode register setting.