A memory controller selects from among a plurality of memory access commands including volatile memory reads, volatile memory writes, non-volatile memory reads, and non-volatile memory writes. The selected memory access commands are transmitted to a heterogenous memory channel coupled to a non-volatile memory and a volatile memory. The non-volatile read commands that are transmitted are stored in a non-volatile command queue (NV queue). A ready response is received from the non-volatile memory indicating that responsive data is available for an associated one of the non-volatile read commands. In response to receiving the ready response, a send command is transmitted for commanding the non-volatile memory to send the responsive data.