Identification and verification of a sector within a block of mass storage flash memory

• US 6,393,513 B2
• Filed: 04/23/2001
• Issued: 05/21/2002
• Est. Priority Date: 07/31/1995
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Lexar Media Incorporated (Micron Technology, Inc.)
• Inventors: Estakhri, Petro, Iman, Berhanu
• Primary Examiner(s): BRAGDON, REGINALD GLENWOOD
• Application Number:
  US09/841,522
• Publication Number:
  US 20010029564A1
• Time in Patent Office: 393 Days
• Field of Search: 711/103, 711/203, 714/42, 714/54
• US Class Current: 711/103
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G06F 12/023 Free address space management
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0652 Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/08 Address circuits; Decoders; Word-line control circuits
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: G11C 29/765 in solid state disks
• CPC Class Codes: G11C 29/82 for EEPROMs

Abstract

A method and apparatus is disclosed for identifying a block being stored within flash memory devices using a cluster address for each block, the block being selectively erasable and having one or more sectors, the cluster address being stored in one of the sectors of the block. In an alternative embodiment, the cluster address is stored in at least two different sectors within the same block for ensuring that the information last written to the block is valid. Further disclosed is a novel way to use a defect flag for each block stored within the flash memory device for efficiently identifying non-defective blocks upon system power-up.

Claims

1. A storage device comprising:

nonvolatile memory coupled to a host for storing information assigned by the host, said nonvolatile memory being organized into blocks, at least a portion of each said block being identified by a physical block address (PBA);

a memory device coupled to said nonvolatile memory for identifying a particular block having one or more rows within said nonvolatile memory in which information is, or is to be stored; and

means associated with said memory device for accessing a block identified by a PBA within said nonvolatile memory and having a block address associated therewith, said associated means accesses at least a portion of a particular PBA to read data therefrom, or to write data into the accessed block, said associated means writes the block address into two different locations within said accessed block, and upon accessing of any block within the nonvolatile memory having data stored therein, said associated means compares the block address written into the two different locations within the block and if they match, said associated means determines that the block is valid for accessing thereof.

2. A storage device as recited in claim 1 wherein if the block addresses do not match, said associated means being operative to erase the block prior to re-use thereof.

3. A storage device as recited in claim 1 wherein each block includes a defect flag that if set, prevents the block from being re-used.