US Patent 10963190 Memory system

A memory system includes a semiconductor storage device and a memory controller. The memory controller includes a command buffer and a descriptor buffer. The memory controller stores a first command received from outside in the command buffer, fetches a first descriptor from the host device, based on the stored first command, stores the fetched first descriptor in the descriptor buffer, stores a second command received from the outside in the command buffer, discards an unused part of the first descriptor from the descriptor buffer, fetches a second descriptor from the host device, based on the stored second command, and stores the fetched second descriptor at an address where the discarded part of the first descriptor was stored.