A circuit is configured to be mounted on a memory module so as to be electrically coupled to a plurality of double-data-rate (DDR) memory devices arranged in one or more ranks on the memory module. The circuit includes a logic element, a register, and a phase-lock loop device. The circuit is configurable to respond to a set of input signals from a computer system to selectively isolate one or more loads of the plurality of DDR memory devices from the computer system and to translate between a system memory domain of the computer system and a physical memory domain of the plurality of DDR memory devices.