Semiconductor device having a volatile semiconductor memory and a nonvolatile semiconductor memory which performs read/write using different size data units

• US 8,065,471 B2
• Filed: 09/02/2009
• Issued: 11/22/2011
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yano, Hirokuni, Kanno, Shinichi, Hida, Toshikatsu, Matsuzaki, Hidenori, Kitsunai, Kazuya, Asano, Shigehiro
• Primary Examiner(s): Verbrugge, Kevin
• Application Number:
  US12/552,442
• Publication Number:
  US 20100037011A1
• Time in Patent Office: 811 Days
• Field of Search: None
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7202 Allocation control and policies
• CPC Class Codes: G06F 2212/7203 Temporary buffering, e.g. using volatile buffer or dedicated buffer blocks
• CPC Class Codes: G06F 2212/7209 Validity control, e.g. using flags, time stamps or sequence numbers
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0658 Controller construction arrangements
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 3/0685 Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays
• CPC Class Codes: G11C 11/5628 Programming or writing circuits; Data input circuits

Abstract

A semiconductor storage device includes a first memory area configured in a volatile semiconductor memory, second, third, and fourth memory areas configured in a nonvolatile semiconductor memory, and a controller which executes following processing. The controller executes a first processing for storing a plurality of data by the first unit in the first memory area, a second processing for storing data by a first management unit in the fourth memory area, a third processing for storing data by a second management unit in the third memory area, a fourth processing for moving an area of the third unit having the oldest allocation order in the fourth memory area to the second memory area, and a fifth processing for selecting data in the second memory area and copying the selected data to an empty area of the third unit in the second memory area.

Claims

1. A semiconductor storage device comprising:

a first memory area provided in a volatile semiconductor memory which performs writing of data by a first unit or less, the first unit being an access unit to the semiconductor storage device;

second, third, and fourth memory areas provided in a nonvolatile semiconductor memory which performs writing of data by a second unit and performs erasing of data by a third unit, the third unit being twice or larger natural number times as large as the second unit; and

a controller executing;

a first processing for storing a plurality of data by the first unit in the first memory area;

a second processing for storing data outputted from the first memory area by a first management unit in the fourth memory area, the first management unit being twice or larger natural number times as large as the first unit and being less than the third unit;

a third processing for storing data outputted from the first memory area by a second management unit in the third memory area, the second management unit being twice or larger natural number times as large as the first management unit;

a fourth processing for moving an area of the third unit having the oldest allocation order in the fourth memory area to the second memory area; and

a fifth processing for selecting valid data in the second memory area and copying the selected valid data to an empty area of the third unit in the second memory area.

2. The semiconductor storage device according to claim 1, wherein in the second processing, the controller:

reads data which comprises data of the first management unit and which is not stored in the first memory area from at least one of the second, third and fourth memory areas; and

merges data stored in the first memory area and data read from at least one of the second, third and fourth memory areas into data of the first management unit.

3. The semiconductor storage device according to claim 1, wherein in the third processing, the controller:

reads data which comprises data of the second management unit and which is not stored in the first memory area from at least one of the second, third and fourth memory areas; and

merges data stored in the first memory area and data read from at least one of the second, third and fourth memory areas into data of the second management unit.

4. The semiconductor storage device according to claim 1, wherein

the second, third and fourth memory areas share the same nonvolatile semiconductor memory, and

the controller allocates areas of the third unit to the second, third and fourth memory areas respectively.

5. The semiconductor storage device according to claim 1, wherein in the first processing, the controller:

calculates a logical address range by aligning a logical address of data inputted to the semiconductor storage device into the first management unit; and

stores data of the first unit in an area of the first management unit corresponding to the logical address range in the first memory area.

6. The semiconductor storage device according to claim 5, wherein in the first processing, the controller:

determines whether the logical address range is available for storing data of the first unit in the first memory area; and

executes at least one of the second and third processing if the logical address range is not available.

7. The semiconductor storage device according to claim 1, wherein the controller:

calculates a logical address range by aligning a logical address of data to be outputted from the first memory area into the second management unit;

counts data of the first management unit which is included in the logical address range and which is stored in the first memory area;

executes the second processing if the sum of counted data is less than a predetermined threshold value; and

executes the third processing if the sum of counted data is equal to the predetermined threshold value or more.

8. The semiconductor storage device according to claim 1, wherein the controller manages allocation order in the fourth memory area with a FIFO structure of the third unit.

9. The semiconductor storage device according to claim 1, wherein the controller executes a sixth processing for:

selecting valid data of the first management unit stored in an area of the third unit having the oldest allocation order in the fourth memory area; and

storing data including the selected valid data by the second management unit in the third memory area.

10. The semiconductor storage device according to claim 9, wherein in the sixth processing, the controller:

calculates a logical address range by aligning a logical address of each valid data in the area of the third unit having the oldest allocation order into the second management unit;

counts valid data of the first management unit which is included in the logical address range and which is stored in the fourth memory area; and

selects valid data included in the logical address range if the sum of counted valid data is a predetermined threshold value or more.

11. The semiconductor storage device according to claim 9, wherein in the sixth processing, the controller:

calculates a logical address range by aligning a logical address of each valid data in the area of the third unit having the oldest allocation order into the second management unit;

counts valid data of the first management unit which is included in the logical address range and which is stored in the second and fourth memory areas;

selects valid data included in the logical address range if the sum of counted valid data is a predetermined threshold value or more.

12. The semiconductor storage device according to claim 9, wherein the controller executes at least one of the fourth and sixth processing if a sum of areas of the third unit occupied by a plurality of valid and invalid data in the fourth memory area exceeds a permissible range.

13. The semiconductor storage device according to claim 1, wherein the controller executes a seventh processing for:

selecting valid data of the first management unit to be outputted from the second memory area; and

storing data including the selected valid data by the second management unit in the third memory area.

14. The semiconductor storage device according to claim 13, wherein in the seventh processing, the controller:

calculates a logical address range by aligning a logical address of the selected data into the second management unit;

reads data included in the logical address range from at least one of the first, second, third and fourth memory areas; and

merges the selected data and data read from at least one of the first, second, third and fourth memory areas into data of the second management unit.

15. The semiconductor storage device according to claim 13, wherein the controller executes at least one of the fifth and seventh processing if a sum of areas of the third unit occupied by a plurality of valid and invalid data stored in the second memory area exceeds a permissible range.

16. The semiconductor storage device according to claim 15, wherein the controller:

executes the fifth processing if a sum of valid data in the second memory area is equal to a sum of data storable in the second memory area or less; and

executes the seventh processing if the sum of valid data in the second memory area is larger than the sum of data storable in the second memory area.

17. The semiconductor storage device according to claim 15, wherein the controller:

selects a first predetermined number of areas of the third unit in order from the one with the smallest number of valid data in the second memory area;

executes the fifth processing if a sum of valid data in the first predetermined number of areas is equal to a sum of data storable in a second predetermined number of areas of the third unit or less; and

executes the seventh processing if the sum of valid data is larger than the sum of data storable in the second predetermined number of areas,

wherein the second predetermined number is smaller than the first predetermined number.

18. The semiconductor storage device according to claim 1, wherein in the fifth processing, the controller selects valid data of the first management unit in areas of the third unit in order from the one with the smallest number of valid data in the second memory area.

19. The semiconductor storage device according to claim 13, wherein in the seventh processing, the controller selects valid data of the first management unit in an area of the third unit having the largest number of valid data in the second memory area.

20. The semiconductor storage device according to claim 1, wherein the second unit is twice or larger natural number times as large as the first management unit.

21. The semiconductor storage device according to claim 1, wherein

the first management unit is twice or larger natural number times as large as the second unit, and

the third unit is twice or larger natural number times as large as the first management unit.

22. The semiconductor storage device according to claim 1, wherein the second management unit is twice or larger natural number times as large as the third unit.

23. The semiconductor storage device according to claim 1, wherein a size of the first management unit is equal to that of the second unit.

24. The semiconductor storage device according to claim 1, wherein a size of the second management unit is equal to that of the third unit.

25. The semiconductor storage device according to claim 1, wherein the volatile semiconductor memory is a DRAM and the nonvolatile semiconductor memory is a NAND type flash memory.

26. The semiconductor storage device according to claim 1, wherein the nonvolatile semiconductor memory includes MLC (Multi Level Cell) areas of the third unit in which multi bits data are programmed to one memory cell.

27. The semiconductor storage device according to claim 1, wherein

the nonvolatile semiconductor memory includes MLC (Multi Level Cell) areas of the third unit in which multi bits data are programmed to one memory cell and SLC (Single Level Cell) areas in which single bit data are programmed to one memory cell, and

the controller allocates the SLC areas to the fourth memory area and the MLC areas to the third memory area.

28. The semiconductor storage device according to claim 27, wherein the controller:

moves the SLC areas storing data of the first management unit to the second memory area from the fourth memory area in the fourth processing;

selects valid data of the first management unit stored in the SLC areas in the second memory area;

copies the selected valid data to the MLC area having empty areas of the second unit; and

allocates the MLC area to the second memory area after copying the selected valid data therein.

120. The semiconductor storage device according to claim 4, wherein the controller releases an area of the third unit in which all of data of the first management unit are invalidated in the area of the third unit which is allocated in the second memory area.

121. The semiconductor storage device according to claim 4, wherein the controller releases an area of the third unit in which all of data of the first management unit are invalidated in the area of the third unit which is allocated in the fourth memory area.

122. The semiconductor storage device according to claim 4, wherein the controller releases an area of the third unit in which all of data of the second management unit are invalidated in the area of the third unit which is allocated in the third memory area.

29. A method of controlling a semiconductor storage device, the semiconductor storage device having a first memory area provided in a volatile semiconductor memory which performs writing of data by a first unit or less;

and second, third and fourth memory areas provided in a nonvolatile semiconductor memory which performs writing of data by a second unit and performs erasing of data by a third unit, the third unit being twice or larger natural number times as large as the second unit, comprising;

accessing the semiconductor storage device by the first unit for writing data;

executing a first processing for storing a plurality of data by the first unit in the first memory area;

executing a second processing for storing data outputted from the first memory area by a first management unit in the fourth memory area, the first management unit being twice or larger natural number times as large as the first unit and being less than the third unit;

executing a third processing for storing data outputted from the first memory area by a second management unit in the third memory area, the second management unit being twice or larger natural number times as large as the first management unit;

executing a fourth processing for moving an area of the third unit having the oldest allocation order in the fourth memory area to the second memory area; and

executing a fifth processing for selecting valid data in the second memory area and copying the selected data to an empty area of the third unit in the second memory area.

30. The method according to claim 29, wherein the second processing includes:

reading data which comprises data of the first management unit and which is not stored in the first memory area from at least one of the second and third memory areas; and

merging data stored in the first memory area and data read from at least one of the second and third memory areas into data of the first management unit.

31. The method according to claim 29, wherein the third processing includes:

reading data which comprises data of the second management unit and which is not stored in the first memory area from at least one of the second and third memory areas; and

merging data stored in the first memory area and data read from at least one of the second and third memory areas into data of the second management unit.

32. The method according to claim 29, wherein the second, third and fourth memory areas share the same nonvolatile semiconductor memory, and further comprising:

allocating areas of the third unit to the second, third and fourth memory areas respectively.

33. The method according to claim 29, wherein the first processing includes:

calculating a logical address range by aligning a logical address of data inputted to the semiconductor storage device into the first management unit; and

storing data of the first unit in an area of the first management unit corresponding to the logical address range in the first memory area.

34. The method according to claim 33, wherein the first processing includes:

determining whether the logical address range is available for storing data of the first unit in the first memory area; and

executing at least one of the second and third processing if the logical address range is not available.

35. The method according to claim 29, further comprising:

calculating a logical address range by aligning a logical address of data to be outputted from the first memory area into the second management unit; and

counting data of the first management unit which is included in the logical address range and which is stored in the first memory area, wherein

the second processing is executed if the sum of counted data is less than a predetermined threshold value, and

the third processing is executed if the sum of counted data is equal to the predetermined threshold value or more.

36. The method according to claim 29, further comprising:

managing allocation order in the fourth memory area with a FIFO structure of the third unit.

37. The method according to claim 29, further comprising:

executing a sixth processing for;

selecting valid data of the first management unit stored in an area of the third unit having the oldest allocation order in the fourth memory area; and

storing data including the selected valid data by the second management unit in the third memory area.

38. The method according to claim 37, wherein the sixth processing includes:

calculating a logical address range by aligning a logical address of each valid data in the area of the third unit having the oldest allocation order into the second management unit;

counting valid data of the first management unit which is included in the logical address range and which is stored in the fourth memory area; and

selecting valid data included in the logical address range if the sum of counted valid data is a predetermined threshold value or more.

39. The method according to claim 37, wherein the sixth processing includes:

calculating a logical address range by aligning a logical address of each valid data in the area of the third unit having the oldest allocation order into the second management unit;

counting valid data of the first management unit which is included in the logical address range and which is stored in the second and fourth memory areas;

selecting valid data included in the logical address range if the sum of counted valid data is a predetermined threshold value or more.

40. The method according to claim 37, wherein at least one of the fourth and sixth processing is executed if a sum of areas of the third unit occupied by a plurality of valid and invalid data in the fourth memory area exceeds a permissible range.

41. The method according to claim 29, further comprising:

executing a seventh processing for;

selecting valid data of the first management unit to be outputted from the second memory area; and

storing data including the selected valid data by the second management unit in the third memory area.

42. The method according to claim 41, wherein the seventh processing includes:

calculating a logical address range by aligning a logical address of the selected data into the second management unit;

reading data included in the logical address range from at least one of the first, second, third and fourth memory areas; and

merging the selected data and data read from at least one of the first, second, third and fourth memory areas into data of the second management unit.

43. The method according to claim 41, wherein at least one of the fifth and seventh processing is executed if a sum of areas of the third unit occupied by a plurality of valid and invalid data stored in the second memory area exceeds a permissible range.

44. The method according to claim 43, wherein

the fifth processing is executed if a sum of valid data in the second memory area is equal to a sum of data storable in the second memory area or less, and

the seventh processing is executed if the sum of valid data in the second memory area is larger than the sum of data storable in the second memory area.

45. The method according to claim 43, further comprising:

selecting a first predetermined number of areas of the third unit in order from the one with the smallest number of valid data in the second memory area, wherein

the fifth processing is executed if a sum of valid data in the first predetermined number of areas is equal to a sum of data storable in a second predetermined number of areas of the third unit or less,

the seventh processing is executed if the sum of valid data is larger than the sum of data storable in the second predetermined number of areas, and

the second predetermined number is smaller than the first predetermined number.

46. The method according to claim 29, wherein the fifth processing includes selecting valid data of the first management unit in areas of the third unit in order from the one with the smallest number of valid data in the second memory area.

47. The method according to claim 41, wherein the seventh processing includes selecting valid data of the first management unit in an area of the third unit having the largest number of valid data in the second memory area.

48. The method according to claim 29, wherein the second unit is twice or larger natural number times as large as the first management unit.

49. The method according to claim 29, wherein

the first management unit is twice or larger natural number times as large as the second unit, and

the third unit is twice or larger natural number times as large as the first management unit.

50. The method according to claim 29, wherein the second management unit is twice or larger natural number times as large as the third unit.

51. The method according to claim 29, wherein a size of the first management unit is equal to that of the second unit.

52. The method according to claim 29, wherein a size of the second management unit is equal to that of the third unit.

53. The method according to claim 29, wherein the volatile semiconductor memory is a DRAM and the nonvolatile semiconductor memory is a NAND type flash memory.

54. The method according to claim 29, wherein the nonvolatile semiconductor memory includes MLC (Multi Level Cell) areas of the third unit in which multi bits data are programmed to one memory cell.

55. The method according to claim 29, wherein

the nonvolatile semiconductor memory includes MLC (Multi Level Cell) areas of the third unit in which multi bits data are programmed to one memory cell and SLC (Single Level Cell) areas in which single bit data are programmed to one memory cell, and further comprising:

allocating the SLC areas to the fourth memory area and the MLC areas to the third memory area.

56. The method according to claim 55, wherein the fourth processing includes moving the SLC areas storing data of the first management unit to the second memory area from the fourth memory area, and further comprising:

selecting valid data of the first management unit stored in the SLC areas in the second memory area;

copying the selected valid data to the MLC area having empty areas of the second unit; and

allocating the MLC area to the second memory area after copying the selected valid data therein.

123. The method according to claim 32, further comprising:

releasing an area of the third unit in which all of data of the first management unit are invalidated in the area of the third unit which is allocated in the second memory area.

124. The method according to claim 32, further comprising:

releasing an area of the third unit in which all of data of the first management unit are invalidated in the area of the third unit which is allocated in the fourth memory area.

125. The method according to claim 32, further comprising:

releasing an area of the third unit in which all of data of the second management unit are invalidated in the area of the third unit which is allocated in the third memory area.

57. An information processing apparatus comprising:

a CPU;

a main memory; and

a semiconductor storage device, wherein

the semiconductor storage device includes;

a first memory area provided in a volatile semiconductor memory which performs writing of data by a first unit or less, the first unit being an access unit to the semiconductor storage device;

second, third, and fourth memory areas provided in a nonvolatile semiconductor memory which performs writing of data by a second unit and performs erasing of data by a third unit, the third unit being twice or larger natural number times as large as the second unit; and

a controller executing;

a first processing for storing a plurality of data by the first unit in the first memory area;

a second processing for storing data outputted from the first memory area by a first management unit in the fourth memory area, the first management unit being twice or larger natural number times as large as the first unit and being less than the third unit;

a third processing for storing data outputted from the first memory area by a second management unit in the third memory area, the second management unit being twice or larger natural number times as large as the first management unit;

a fourth processing for moving an area of the third unit having the oldest allocation order in the fourth memory area to the second memory area; and

a fifth processing for selecting data in the second memory area and copying the selected data to an empty area of the third unit in the second memory area.

58. The information processing apparatus according to claim 57, the semiconductor storage device is controlled through an ATA interface.

59. The information processing apparatus according to claim 58, wherein the semiconductor storage device is accessed using a logical address of the first unit.

60. The information processing apparatus according to claim 57, wherein the semiconductor storage device stores an operating system executed by the CPU.

61. The information processing apparatus according to claim 60, wherein the main memory temporary stores the operating system loaded from the semiconductor storage device.

62. The information processing apparatus according to claim 61, wherein the main memory is a DRAM directory accessed by the CPU.

63. The information processing apparatus according to claim 57, wherein in the second processing, the controller:

reads data which comprises data of the first management unit and which is not stored in the first memory area from at least one of the second, third and fourth memory areas; and

merges data stored in the first memory area and data read from at least one of the second, third and fourth memory areas into data of the first management unit.

64. The information processing apparatus according to claim 57, wherein in the third processing, the controller:

reads data which comprises data of the second management unit and which is not stored in the first memory area from at least one of the second, third and fourth memory areas; and

merges data stored in the first memory area and data read from at least one of the second, third and fourth memory areas into data of the second management unit.

65. The information processing apparatus according to claim 57, wherein

the second, third and fourth memory areas share the same nonvolatile semiconductor memory, and

the controller allocates areas of the third unit to the second, third and fourth memory areas respectively.

66. The information processing apparatus according to claim 57, wherein in the first processing, the controller:

calculates a logical address range by aligning a logical address of data inputted to the semiconductor storage device into the first management unit; and

stores data of the first unit in an area of the first management unit corresponding to the logical address range in the first memory area.

67. The information processing apparatus according to claim 66, wherein in the first processing, the controller:

determines whether the logical address range is available for storing data of the first unit in the first memory area; and

executes at least one of the second and third processing if the logical address range is not available.

68. The information processing apparatus according to claim 57, wherein the controller:

calculates a logical address range by aligning a logical address of data to be outputted from the first memory area into the second management unit;

counts data of the first management unit which is included in the logical address range and which is stored in the first memory area;

executes the second processing if the sum of counted data is less than a predetermined threshold value; and

executes the third processing if the sum of counted data is equal to the predetermined threshold value or more.

69. The information processing apparatus according to claim 57, wherein the controller manages allocation order in the fourth memory area with a FIFO structure of the third unit.

70. The information processing apparatus according to claim 57, wherein the controller executes a sixth processing for:

selecting valid data of the first management unit stored in an area of the third unit having the oldest allocation order in the fourth memory area; and

storing data including the selected valid data by the second management unit in the third memory area.

71. The information processing apparatus according to claim 70, wherein in the sixth processing, the controller:

calculates a logical address range by aligning a logical address of each valid data in the area of the third unit having the oldest allocation order into the second management unit;

counts valid data of the first management unit which is included in the logical address range and which is stored in the fourth memory area; and

selects valid data included in the logical address range if the sum of counted valid data is a predetermined threshold value or more.

72. The information processing apparatus according to claim 70, wherein in the sixth processing, the controller:

calculates a logical address range by aligning a logical address of each valid data in the area of the third unit having the oldest allocation order into the second management unit;

counts valid data of the first management unit which is included in the logical address range and which is stored in the second and fourth memory areas;

selects valid data included in the logical address range if the sum of counted valid data is a predetermined threshold value or more.

73. The information processing apparatus according to claim 70, wherein the controller executes at least one of the fourth and sixth processing if a sum of areas of the third unit occupied by a plurality of valid and invalid data in the fourth memory area exceeds a permissible range.

74. The information processing apparatus according to claim 57, wherein the controller executes a seventh processing for:

selecting valid data of the first management unit to be outputted from the second memory area; and

storing data including the selected valid data by the second management unit in the third memory area.

75. The information processing apparatus according to claim 74, wherein in the seventh processing, the controller:

calculates a logical address range by aligning a logical address of the selected data into the second management unit;

reads data included in the logical address range from at least one of the first, second, third and fourth memory areas; and

merges the selected data and data read from at least one of the first, second, third and fourth memory areas into data of the second management unit.

76. The information processing apparatus according to claim 74, wherein the controller executes at least one of the fifth and seventh processing if a sum of areas of the third unit occupied by a plurality of valid and invalid data stored in the second memory area exceeds a permissible range.

77. The information processing apparatus according to claim 76, wherein the controller:

executes the fifth processing if a sum of valid data in the second memory area is equal to a sum of data storable in the second memory area or less; and

executes the seventh processing if the sum of valid data in the second memory area is larger than the sum of data storable in the second memory area.

78. The information processing apparatus according to claim 76, wherein the controller:

selects a first predetermined number of areas of the third unit in order from the one with the smallest number of valid data in the second memory area;

executes the fifth processing if a sum of valid data in the first predetermined number of areas is equal to a sum of data storable in a second predetermined number of areas of the third unit or less; and

executes the seventh processing if the sum of valid data is larger than the sum of data storable in the second predetermined number of areas,

wherein the second predetermined number is smaller than the first predetermined number.

79. The information processing apparatus according to claim 57, wherein in the fifth processing, the controller selects valid data of the first management unit in areas of the third unit in order from the one with the smallest number of valid data in the second memory area.

80. The information processing apparatus according to claim 74, wherein in the seventh processing, the controller selects valid data of the first management unit in an area of the third unit having the largest number of valid data in the second memory area.

81. The information processing apparatus according to claim 57, wherein the second unit is twice or larger natural number times as large as the first management unit.

82. The information processing apparatus according to claim 57, wherein

the first management unit is twice or larger natural number times as large as the second unit, and

the third unit is twice or larger natural number times as large as the first management unit.

83. The information processing apparatus according to claim 57, wherein the second management unit is twice or larger natural number times as large as the third unit.

84. The information processing apparatus according to claim 57, wherein a size of the first management unit is equal to that of the second unit.

85. The information processing apparatus according to claim 57, wherein a size of the second management unit is equal to that of the third unit.

86. The information processing apparatus according to claim 57, wherein the volatile semiconductor memory is a DRAM and the nonvolatile semiconductor memory is a NAND type flash memory.

87. The information processing apparatus according to claim 57, wherein the nonvolatile semiconductor memory includes MLC (Multi Level Cell) areas of the third unit in which multi bits data are programmed to one memory cell.

88. The information processing apparatus according to claim 57, wherein

the nonvolatile semiconductor memory includes MLC (Multi Level Cell) areas of the third unit in which multi bits data are programmed to one memory cell and SLC (Single Level Cell) areas in which single bit data are programmed to one memory cell, and

the controller allocates the SLC areas to the fourth memory area and the MLC areas to the third memory area.

89. The information processing apparatus according to claim 88, wherein the controller:

moves the SLC areas storing data of the first management unit to the second memory area from the fourth memory area in the fourth processing;

selects valid data of the first management unit stored in the SLC areas in the second memory area;

copies the selected valid data to the MLC area having empty areas of the second unit; and

allocates the MLC area to the second memory area after copying the selected valid data therein.

126. The information processing apparatus according to claim 65, wherein the controller releases an area of the third unit in which all of data of the first management unit are invalidated in the area of the third unit which is allocated in the second memory area.

127. The information processing apparatus according to claim 65, wherein the controller releases an area of the third unit in which all of data of the first management unit are invalidated in the area of the third unit which is allocated in the fourth memory area.

128. The information processing apparatus according to claim 65, wherein the controller releases an area of the third unit in which all of data of the second management unit are invalidated in the area of the third unit which is allocated in the third memory area.

90. A controller, which controls a first memory area provided in a volatile semiconductor memory which performs writing of data by a first unit or less, the first unit being an access unit to the semiconductor storage device;

and second, third, and fourth memory areas provided in a nonvolatile semiconductor memory which performs writing of data by a second unit and performs erasing of data by a third unit, the third unit being twice or larger natural number times as large as the second unit, comprising;

a data control unit which executes;

a first processing for storing a plurality of data by the first unit in the first memory area;

a second processing for storing data outputted from the first memory area by a first management unit in the fourth memory area, the first management unit being twice or larger natural number times as large as the first unit and being less than the third unit;

a third processing for storing data outputted from the first memory area by a second management unit in the third memory area, the second management unit being twice or larger natural number times as large as the first management unit;

a fourth processing for moving an area of the third unit having the oldest allocation order in the fourth memory area to the second memory area; and

a fifth processing for selecting data in the second memory area and copying the selected data to an empty area of the third unit in the second memory area.

91. The controller according to claim 90, further comprising:

an ATA command processing unit which performs data transfer to the first memory area in cooperation with the data control unit.

92. The controller according to claim 90, further comprising:

a security control unit which controls security information in cooperation with the data control unit.

93. The controller according to claim 90, wherein in the second processing, the data control unit:

reads data which comprises data of the first management unit and is not stored in the first memory area from at least one of the second, third and fourth memory areas; and

merges data stored in the first memory area and data read from at least one of the second, third and fourth memory areas into data of the first management unit.

94. The controller according to claim 90, wherein in the third processing, the data control unit:

reads data which comprises data of the second management unit and which is not stored in the first memory area from at least one of the second, third and fourth memory areas; and

merges data stored in the first memory area and data read from at least one of the second, third and fourth memory areas into data of the second management unit.

95. The controller according to claim 90, wherein

the second, third and fourth memory areas share the same nonvolatile semiconductor memory, and

the data control unit allocates areas of the third unit to the second, third and fourth memory areas respectively.

96. The controller according to claim 90, wherein in the first processing, the data control unit:

calculates a logical address range by aligning a logical address of data inputted to the semiconductor storage device into the first management unit; and

stores data of the first unit in an area of the first management unit corresponding to the logical address range in the first memory area.

97. The controller according to claim 96, wherein in the first processing, the data control unit:

determines whether the logical address range is available for storing data of the first unit in the first memory area; and

executes at least one of the second and third processing if the logical address range is not available.

98. The controller according to claim 90, wherein the data control unit:

calculates a logical address range by aligning a logical address of data to be outputted from the first memory area into the second management unit;

counts data of the first management unit which is included in the logical address range and which is stored in the first memory area;

executes the second processing if the sum of counted data is less than a predetermined threshold value; and

executes the third processing if the sum of counted data is equal to the predetermined threshold value or more.

99. The controller according to claim 90, wherein the data control unit manages allocation order in the fourth memory area with a FIFO structure of the third unit.

100. The controller according to claim 90, wherein the data control unit executes a sixth processing for:

selecting valid data of the first management unit stored in an area of the third unit having the oldest allocation order in the fourth memory area; and

storing data including the selected valid data by the second management unit in the third memory area.

101. The controller according to claim 100, wherein in the sixth processing, the data control unit:

calculates a logical address range by aligning a logical address of each valid data in the area of the third unit having the oldest allocation order into the second management unit;

counts valid data of the first management unit which is included in the logical address range and which is stored in the fourth memory area; and

selects valid data included in the logical address range if the sum of counted valid data is a predetermined threshold value or more.

102. The controller according to claim 100, wherein in the sixth processing, the data control unit:

calculates a logical address range by aligning a logical address of each valid data in the area of the third unit having the oldest allocation order into the second management unit;

counts valid data of the first management unit which is included in the logical address range and which is stored in the second and fourth memory areas;

selects valid data included in the logical address range if the sum of counted valid data is a predetermined threshold value or more.

103. The controller according to claim 90, wherein the data control unit executes at least one of the fourth and sixth processing if a sum of areas of the third unit occupied by a plurality of valid and invalid data in the fourth memory area exceeds a permissible range.

104. The controller according to claim 90, wherein the data control unit executes a seventh processing for:

selecting valid data of the first management unit to be outputted from the second memory area; and

storing data including the selected valid data by the second management unit in the third memory area.

105. The controller according to claim 104, wherein in the seventh processing, the data control unit:

calculates a logical address range by aligning a logical address of the selected data into the second management unit;

reads data included in the logical address range from at least one of the first, second, third and fourth memory areas; and

merges the selected data and data read from at least one of the first, second, third and fourth memory areas into data of the second management unit.

106. The controller according to claim 104, wherein the data control unit executes at least one of the fifth and seventh processing if a sum of areas of the third unit occupied by a plurality of valid and invalid data stored in the second memory area exceeds a permissible range.

107. The controller according to claim 106, wherein the data control unit:

executes the fifth processing if a sum of valid data in the second memory area is equal to a sum of data storable in the second memory area or less; and

executes the seventh processing if the sum of valid data in the second memory area is larger than the sum of data storable in the second memory area.

108. The controller according to claim 106, wherein the data control unit:

selects a first predetermined number of areas of the third unit in order from the one with the smallest number of valid data in the second memory area;

executes the fifth processing if a sum of valid data in the first predetermined number of areas is equal to a sum of data storable in a second predetermined number of areas of the third unit or less; and

executes the seventh processing if the sum of valid data is larger than the sum of data storable in the second predetermined number of areas,

wherein the second predetermined number is smaller than the first predetermined number.

109. The controller according to claim 90, wherein in the fifth processing, the data control unit selects valid data of the first management unit in areas of the third unit in order from the one with the smallest number of valid data in the second memory area.

110. The controller according to claim 104, wherein in the seventh processing, the data control unit selects valid data of the first management unit in an area of the third unit having the largest number of valid data in the second memory area.

111. The controller according to claim 90, wherein the second unit is twice or larger natural number times as large as the first management unit.

112. The controller according to claim 90, wherein

the first management unit is twice or larger natural number times as large as the second unit, and

the third unit is twice or larger natural number times as large as the first management unit.

113. The controller according to claim 90, wherein the second management unit is twice or larger natural number times as large as the third unit.

114. The controller according to claim 90, wherein a size of the first management unit is equal to that of the second unit.

115. The controller according to claim 90, wherein a size of the second management unit is equal to that of the third unit.

116. The controller according to claim 90, wherein the volatile semiconductor memory is a DRAM and the nonvolatile semiconductor memory is a NAND type flash memory.

117. The controller according to claim 90, wherein the nonvolatile semiconductor memory includes MLC (Multi Level Cell) areas of the third unit in which multi bits data are programmed to one memory cell.

118. The controller according to claim 90, wherein

the nonvolatile semiconductor memory includes MLC (Multi Level Cell) areas of the third unit in which multi bits data are programmed to one memory cell and SLC (Single Level Cell) areas in which single bit data are programmed to one memory cell, and

the data control unit allocates the SLC areas to the fourth memory area and the MLC areas to the third memory area.

119. The controller according to claim 118, wherein the data control unit:

moves the SLC areas storing data of the first management unit to the second memory area from the fourth memory area in the fourth processing;

selects valid data of the first management unit stored in the SLC areas in the second memory area;

copies the selected valid data to the MLC area having empty areas of the second unit; and

allocates the MLC area to the second memory area after copying the selected valid data therein.

129. The controller according to claim 95, wherein the data control unit releases an area of the third unit in which all of data of the first management unit are invalidated in the area of the third unit which is allocated in the second memory area.

130. The controller according to claim 95, wherein the data control unit releases an area of the third unit in which all of data of the first management unit are invalidated in the area of the third unit which is allocated in the fourth memory area.

131. The controller according to claim 95, wherein the data control unit releases an area of the third unit in which all of data of the second management unit are invalidated in the area of the third unit which is allocated in the third memory area.