Memory device testing to support address-differentiated refresh rates

A method of testing a dynamic random access memory (DRAM) device that has N rows of storage cells and that requires, in at least one operating mode, at least N refresh commands to be received from an external source within a specified time interval, the method comprising:

• testing retention of the rows in a first retention test to identify rows that fail to retain data over the specified time interval;
• testing retention of the rows that fail to retain data over the specified time interval in a second retention test to identify rows that retain data over an abbreviated time interval, the abbreviated time interval being shorter than the specified time interval;
• and
• testing retention of rows that retain data over the specified time interval in a third retention test to identify rows that retain data over an extended time interval, the extended time interval being longer than the specified time interval.

A memory module comprising:

• a substrate;
• a plurality of dynamic random access memory (DRAM) devices mounted to the substrate including a first DRAM device having a plurality of rows of storage cells that retain data for at least a first retention time and a row of storage cells that retains data for a limited time that is shorter than the first retention time;
• and
• a non-volatile storage device mounted to the substrate and having stored therein (i) data that indicates an address of the row of storage cells that retains data for a limited time that is shorter than the first retention time and (ii) data that indicates which of the plurality of DRAM devices contains the row of storage cells that retains data for a limited time that is shorter than the first retention time.