Flash memory card with block memory address arrangement

• US 5,905,993 A
• Filed: 04/09/1997
• Issued: 05/18/1999
• Est. Priority Date: 11/09/1994
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Shinohara, Takayuki
• Primary Examiner(s): Chan, Eddie P.
• Assistant Examiner(s): NGUYEN, THAN VINH
• Application Number:
  US08/827,861
• Time in Patent Office: 769 Days
• Field of Search: 395/500, 395/310, 365/218, 711/4, 711/112, 711/171, 711/102, 711/103, 711/202, 711/206
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0292 using tables or multilevel address translation means G06F12/023 takes precedence; address translation in virtual memory systems G06F12/10
• CPC Class Codes: G06F 2212/2022 Flash memory
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

A flash disk card using a flash memory is provided with MPU for converting the cylinder, head and sector numbers, which are input from a host device, into a logical block address (LBA) and a sector address in block format, determining a physical block address (PBA) having the same size as that of an erase block from the logical block address with reference to a logical/physical block address conversion table stored in the flash memory, and accessing the flash memory on the basis of the physical block address. The flash disk card permits a decrease in size of the address conversion table, can be constructed at low cost, and has no need for constructing the table at each time a power supply is turned on.

Claims

1. A flash disk card comprising:

a main electrically rewritable nonvolatile flash memory for storing data in memory blocks of uniform memory capacity, each memory block having a physical address related to location of the block in said main memory and a logical address related to contents of the memory block, individual memory blocks being erased as an erase block unit; and

access means for converting a logical block address of a memory block, equal in memory capacity to an erase block, into a physical block address of a memory block, equal in memory capacity to an erase block, and for accessing the flash memory based on the physical block address, wherein said access means converts a cylinder number, a head number, and a sector number, input to said access means from outside said flash disk card, into a logical block address of a memory block and a sector address in that memory block, converts the logical block address into a physical block address, and accesses said flash memory based on the physical block address and the sector address.

2. The flash disk card according to claim 1 wherein said access means includes a logical/physical block address conversion table for converting logical block addresses into physical block addresses by referring to the logical/physical block address conversion table.

3. The flash disk card according to claim 2 wherein said access means includes a flash disk control circuit for converting the cylinder number, the head number, and the sector number into a logical sector address and a microprocessor for converting the logical sector address into the logical block address and the sector address.

4. The flash disk card according to claim 3 wherein if the logical sector address is LSA, the cylinder number is C, each cylinder has HpC heads, the head number is H, each head has SpH sectors, and the sector number is S, then

5. The flash disk card according to claim 3 wherein if the logical block address is LBA, the logical sector address is LSA, and each block has SpB sectors,

6. The flash disk card according to claim 2 wherein the logical/physical block address conversion table stores logical block addresses and physical block addresses in one-to-one correspondence.

7. The flash disk card according to claim 6 wherein the logical/physical block address conversion table is stored in a second electrically rewritable nonvolatile flash memory.

8. The flash disk card according to claim 7 wherein said second electrically rewritable nonvolatile flash memory comprises a portion of said main electrically rewritable nonvolatile flash memory.

9. The flash disk card according to claim 7 wherein said second electrically rewritable nonvolatile flash memory is separate from said main electrically rewritable nonvolatile flash memory.

10. The flash disk card according to claim 7 wherein each memory block has a block ID area for storing the logical block address of the memory block and at least one sector.

11. The flash disk card according to claim 10 wherein each sector has a sector ID area for storing an invalid sector flag, a sector use flag, and the sector address, and a sector data area for storing data.

12. The flash disk card according to claim 11 wherein each sector ID area is contiguous to a sector data area in a memory block.

13. The flash disk card according to claim 11 wherein all sector ID areas in a memory block are arranged together, sequentially, in a memory block.

14. The flash disk card according to claim 11 wherein all sector data areas in a memory block are arranged together, sequentially, in a memory block.

15. The flash disk card according to claim 10 wherein the block ID area further stores an erasing characteristic.

16. The flash disk card according to claim 15 wherein the erasing characteristic is erasure cycles of the memory block.

17. The flash disk card according to claim 15 wherein the erasing characteristic is erasure time of the memory block.

18. The flash disk card according to claim 15 wherein the erasing characteristic is pulses required for erasure of the memory block.

19. A flash disk card for use with conventional memory access signals designating a memory address of a hard disk memory in terms of a cylinder number, a head number, and a sector number of the hard disk memory, each sector having a fixed memory capacity, said flash disk card comprising:

a main electrically rewritable nonvolatile flash memory for storing data in memory blocks of uniform memory capacity, each memory block having a physical address related to a location of the block in said main memory and a logical address related to contents of the memory block, individual memory blocks being erased as an erase block unit, each memory block including a block ID area for storing a logical block address of the memory block and a plurality of sectors, each sector having the same memory capacity as a sector of the hard disk; and

access means for converting a logical block address of a memory block, equal in memory capacity to an erase block, into a physical block address of a memory block, equal in memory capacity to an erase block, and for accessing the flash memory based on the physical block address, wherein said access means converts a cylinder number, a head number, and a sector number, input to said access means from outside said flash disk card, into a logical block address of a memory block and a sector address in that memory block, converts the logical block address into a physical block address, and accesses said flash memory based on the physical block address and the sector address.