Patent ID: 8868851

Claim:
A data access method of a memory device, wherein the memory device comprises a plurality of memories, comprising: storing a plurality of commands sequentially received from a host in a command queue; retrieving a target command from the command queue; determining a target memory accessed by the target command; determining whether the target memory is in a busy state; when the target memory is not in a busy state, performing access operations requested by the target command; and when the target memory is in a busy state, selecting a substitute command from a plurality of subsequent commands stored in the command queue and performing access operations requested by the substitute command, wherein the sequence of the subsequent commands in the command queue is subsequent to the target command, wherein selection of the substitute command comprises: selecting a candidate substitute command from the subsequent commands stored in the command queue; determining a logical address range accessed by the candidate substitute command; determining a plurality of reference address ranges accessed by a plurality of prior commands stored in the command queue, wherein the sequence of the prior commands in the command queue is prior to the substitute command; determining whether the logical address range overlaps with the reference address ranges; when the logical address range does not overlap with any of the reference address ranges, determining the substitute command to be the candidate substitute command; and when the logical address range overlaps with any of the reference address ranges, selecting a new candidate substitute command from the subsequent commands stored in the command queue as a candidate of the substitute command.