US Patent 7457909 Controlling operation of flash memories

A method controls write/erase operations in a memory device, such as a NAND flash memory. The method includes dividing the memory device in physical blocks, wherein each physical block is comprised of a number of pages; considering the memory device as comprising consecutive virtual blocks, each virtual block including consecutive sectors; associating to each virtual block a virtual block number; selecting the size of the virtual blocks equal to a multiple of the size of the physical blocks; and creating a virtual-to-physical mapping table having entries. Each entry in the mapping table stores a pointer to a root node of a tree structure that links logically a set of physical blocks in the memory device.