Direct logical block addressing flash memory mass storage architecture

A mass storage device having nonvolatile memory, the storage device being coupled to an external digital system for storing binary information therefor in the nonvolatile memory, the storage device for receiving, from the external digital system, a plurality of logical block addresses for identifying the binary information and generating a plurality of physical block addresses corresponding to the logical block addresses, each physical block address for use in identifying locations within the nonvolatile memory for storing or reading the binary information, comprising:

• a. a volatile memory device having a plurality of volatile memory locations each of which is uniquely addressable by one of the logical block addresses and one of the physical block addresses, the volatile memory device configured to store physical block addresses in volatile memory locations identified by the logical block addresses and further being configured to store flags in volatile memory locations identified by the physical block addresses;
• b. one or more nonvolatile memory devices each having a plurality of nonvolatile data blocks, each block being selectively programmable and erasable, being uniquely addressable by one of the physical block addresses, and having associated therewith shadow flags for indicating the status of the block;
• and
• c. a controller operative to receive a block of data, identified by a target logical block address, from the external digital system for storing thereof in the one or more nonvolatile memory devices, to identify a free block within the nonvolatile data blocks having no data stored therein and having a particular physical block address, to store the received block of data and the target logical block address in the free block, to update the shadow flags so as to reflect the current status of the block identified by the target logical block address, and to store the particular physical block address and the shadow flags in the volatile memory location identified by the target logical block address,
• wherein during power-up the physical block addresses are used to address the volatile memory locations and update the flags thereof with the shadow flags of the nonvolatile data blocks and the logical block addresses that are stored the nonvolatile data blocks are utilized to update the physical block addresses of the volatile memory locations with the physical block address that were most recently assigned to the logical block addresses prior to power-up and further wherein periodically all blocks of the one or more nonvolatile memory devices having shadow flags which are set are erased thereby avoiding the need for an erase cycle each time the external system writes to the storage device.

A method of transferring digital information between a host and one or more nonvolatile memory devices under the direction of a controller and with the use of a volatile memory, the digital information that is to be stored in the one or more nonvolatile memory devices being provided by the host to the controller in the form of blocks identified by logical block addresses and stored in nonvolatile memory blocks identified by physical block addresses stored within the volatile memory, the logical block addresses each being used to uniquely address a corresponding physical block address within the volatile memory, having a plurality of volatile memory locations each of which is uniquely addressable by one of the logical block addresses and one of the physical block addresses, the volatile memory configured to store physical block addresses in volatile memory locations identified by the logical block addresses and further being configured to store flags in volatile memory locations identified by the physical block addresses, each of the one or more nonvolatile memory devices having a plurality of nonvolatile data blocks with each block being selectively programmable and erasable, being uniquely addressable by one of the physical block addresses, and having associated therewith shadow flags for indicating the status of the block, the method comprising:

• receiving target logical block addresses and data organized in blocks from the host, the target logical block addresses for identifying the received data blocks;
• locating free blocks within the one or more nonvolatile devices identified by physical block addresses;
• storing the received data blocks and the target logical block addresses in the free blocks;
• updating shadow flags in corresponding nonvolatile memory blocks so as to reflect the current status of the stored data block;
• storing the physical block addresses that identify the free blocks in the volatile memory locations identified by the target logical block addresses;
• storing the shadow flags in flag locations within the volatile memory locations identified by the target logical block addresses;
• and
• during power-up, updating the flag locations within the volatile memory locations by using the physical block addresses to address the flag locations and updating the physical block addresses stored within the volatile memory locations with the physical block addresses that were most recently assigned to the target logical block addresses prior to power-up by using the target logical block addresses,
• wherein periodically all blocks of the nonvolatile memory devices having shadow flags which are set are erased thereby avoiding the need for an erase cycle each time the digital information is transferred from the host to the storage device.