High Density High Reliability Memory Module with Power Gating and a Fault Tolerant Address and Command Bus

摘要

An enhanced four rank enabled buffer device that includes input ports for receiving input data that includes address and command data directed to one or more of up to four ranks of memory devices. The buffer device also includes one or more buffer circuits for driving one or more of the address and command data, a plurality of chip select input lines for selecting between the up to four ranks of memory devices, and a plurality of chip select output lines for accessing the up to four ranks of memory devices. The buffer device further includes a power savings means for causing one or more of the buffer circuits to be in an inactive mode when corresponding chip select input lines are not active. The buffer device is operable to access the up to four ranks of memory devices.