SEMICONDUCTOR MEMORY DEVICE
According to one embodiment, a semiconductor memory device includes: a first component including a controller which issues an instruction complying with a NAND interface; and a second component including a first NAND flash memory which is controlled by the instruction, the second component being removable from the first component.
1 . A semiconductor memory device comprising:
a first component including a controller which issues an instruction complying with a NAND interface; and
a second component including a first NAND flash memory to be controlled by the instruction, the second component being removable from the first component.
2 . The device according to claim 1 , wherein the first component further includes a second NAND flash memory to be controlled by the instruction.
3 . The device according to claim 2 , wherein the controller stores data of a block whose rewrite count is not less than a reference value in the first NAND flash memory and data of a block whose rewrite count is less than the reference value in the second NAND flash memory.
4 . The drive according to claim 2 , wherein the controller writes data to the first NAND flash memory, and moves the data of a block in the first NAND flash memory whose rewrite count is less than the reference value to the second NAND flash memory.
5 . The drive according to claim 2 , wherein the controller writes data to the first NAND flash memory or the second NAND flash memory, moves the data of a block in the first NAND flash memory whose rewrite count is less than the reference value to the second NAND flash memory, and moves the data of a block in the second NAND flash memory whose rewrite count is not less than the reference value to the first NAND flash memory.
6 . The device according to claim 3 , wherein the controller changes the reference value according to free spaces of the first NAND flash memory and the second NAND flash memory.
7 . The device according to claim 1 , wherein the controller initializes to the first NAND flash memory, after the second component is inserted into the first component.
8 . The device according to claim 1 , wherein a wiring for input/output signal between the controller and the first NAND flash memory is a serial wiring.
9 . The device according to claim 2 , wherein a wiring for input/output signal between the controller and the second NAND flash memory is a serial wiring.
10 . The device according to claim 2 , wherein
the first NAND flash memory comprises a NAND flash memory of one of an eMLC type and an SLC type, and
the second NAND flash memory comprises a NAND flash memory of a TLC type.
11 . The device according to claim 1 , wherein the semiconductor memory device comprises a solid state drive.
12 . A semiconductor memory device comprising:
a first circuit board;
a second circuit board being different from the first circuit board;
a first NAND flash memory mounted in the first circuit board;
a second NAND flash memory mounted in the second circuit board; and
a controller mounted in the second circuit board,
wherein wirings for input/output signal between the controller and the first NAND flash memory and between the controller and the second NAND flash memory are serial wirings.
13 . The device according to claim 12 , wherein the serial wirings are differential serial wirings.
14 . The device according to claim 12 , further comprising a connector connecting the first circuit board and the second circuit board.
15 . The device according to claim 12 , wherein
a wiring structure between the controller and the first NAND flash memory is a same as a wiring structure between the controller and the second NAND flash memory.
16 . The device according to claim 12 , wherein
a communication mode between the controller and the first NAND flash memory is a same as a communication mode between the controller and the second NAND flash memory.
17 . A solid state drive comprising:
a first component including a controller; and
a second component including a first nonvolatile semiconductor memory to be controlled by the controller, the second component being removable from the first component.
18 . The drive according to claim 17 , wherein the first component further includes a second nonvolatile semiconductor memory to be controlled by the controller.
19 . The device according to claim 17 , wherein a wiring for input/output signal between the controller and the first nonvolatile semiconductor memory is a serial wiring.
20 . The device according to claim 18 , wherein a wiring for input/output signal between the controller and the second nonvolatile semiconductor memory is a serial wiring.