1. A method of managing direct memory access (DMA) descriptors for commands to a non-volatile semiconductor storage device, the method comprising: requesting DMA descriptors from the host system for each of a plurality of the commands stored in a command random access memory (RAM); storing the DMA descriptors for each of the plurality of the commands in free descriptor regions in a descriptor RAM; and maintaining a dynamic descriptor list in the descriptor RAM for each of the plurality of commands, the dynamic descriptor list for each of the plurality of commands comprising occupied descriptor regions in the descriptor RAM having associated DMA descriptors.