In various embodiments, dedicated mask pins are eliminated by sending a data mask on address lines of the interface. A memory controller receives a request for a memory write operation from a memory client and determines the granularity of the write data from a write data mask sent by the client. Granularity, as used herein, indicates a quantity of write data to which each bit of the received write data mask applies. In an embodiment, the memory controller generates a particular write command and a particular write data mask based on the granularity of the write data. The write command generated is typically the most efficient of several write commands available, but embodiments are not so limited. The write command is transmitted on command lines of the interface, and the write data mask is transmitted on address lines of the interface.