Non-volatile memory, method of operating the same, memory system including the same, and method of operating the system

1. A nonvolatile memory device, comprising:

an array of nonvolatile memory cells;

a plurality of page buffers configured to receive a corresponding plurality of pages of data read from a target page of nonvolatile memory cells in said array using different read voltage conditions for each of the plurality of pages of data being read;

a control circuit electrically coupled to said plurality of page buffers, said control circuit configured to perform a test operation by driving said plurality of page buffers with control signals that cause generation within the nonvolatile memory device of a string of XOR data bits that are derived from at least two of the plurality of pages of data read from the target page of the nonvolatile memory cells using the different read voltage conditions; and

an input/output device configured to output test data derived from the string of XOR data bits to another device located external to the nonvolatile memory device; and

wherein the test operation comprises:

storing first data, which is read from the target page using first read voltage conditions, in a first of the plurality of page buffers;

storing second data, which is read from the target page using second read voltage conditions that differ from the first read voltage conditions, in a second of the plurality of page buffers; and

changing third data in a third of the plurality of page buffers using at least part of the first data transferred from the first page buffer and at least part of the second data transferred from the second page buffer to generate data, which is the same as bit-wise XOR data with respect to the first data and the second data.

2. The nonvolatile memory device of claim 1 , wherein said input/output device is configured to output the test data to a flash memory controller.

3. The nonvolatile memory device of claim 2 , wherein the test data is the string of XOR data bits.

4. The nonvolatile memory device of claim 2 , wherein the test data is a count of a number of asserted bits in the string of XOR data bits.

5. A method of operating a non-volatile memory, the method comprising:

storing first data, which is read from a target page using a first read voltage level, in a first page buffer;

storing second data, which is read from the target page using a second read voltage level, in a second page buffer; and

changing third data in a third page buffer using at least part of the first data transferred from the first page buffer and at least part of the second data transferred from the second page buffer to generate data, which is the same as bit-wise XOR data with respect to the first data and the second data.

6. The method of claim 5 , wherein the first data is transferred to the first page buffer through the third page buffer, and the second data is transferred to the second page buffer through the third page buffer.

7. The method of claim 5 , wherein when the at least part of the first data is a first group of bits, which are included in the first data and have a first value, and the at least part of the second data is a second group of bits, which are included in the second data and have the first value,

the changing the third data including:

(a) initializing each value of bits included in the third data to the first value;

(b) changing each value of bits corresponding to the first group among bits included in the third data, which has been initialized in operation (a), to a second value;

(c) changing each value of bits corresponding to the second group among bits included in the third data, which has been changed in operation (b), to the second value; and

(d) changing each value of common bits among bits comprised in the third data, which has been changed in operation (c), to the first value, and each of the common bit is a bit corresponding to bits that have the first value at the same position in both of the first group and the second group.

8. The method of claim 7 , wherein the first value is one of “0” and “1” and the second value is the other one of the “0” and the “1”.

9. The method of claim 5 , further comprising:

performing a bit-wise XOR operation on reference data and the data that is the same as the bit-wise XOR data using an XOR logic circuit; and

counting the number of bits having a particular value in data output from the XOR logic circuit and outputting a count value to a controller, using a counter.

10. A method of operating a memory system, which includes a non-volatile memory and a controller controlling an operation of the non-volatile memory, the method comprising:

the non-volatile memory storing first data, which is read from a target page using a first read voltage level, in a first page buffer during a first read operation;

the non-volatile memory storing second data, which is read from the target page using a second read voltage level, in a second page buffer during a second read operation; and

the non-volatile memory changing third data in a third page buffer using at least part of the first data transferred from the first page buffer and at least part of the second data transferred from the second page buffer to generate data, which is the same as bit-wise logic operation data with respect to the first data and the second data during a test mode operation.

11. The method of claim 10 , wherein the bit-wise logic operation data is bit-wise XOR data or bit-wise exclusive NOR data.

12. The method of claim 10 , further comprising:

the controller transmitting a first read voltage level change command for setting the first read voltage level and a first read command for controlling the first read operation to the non-volatile memory; and

the controller transmitting a second read voltage level change command for setting the second read voltage level and a second read command for controlling the second read operation to the non-volatile memory.

13. The method of claim 10 , wherein when the at least part of the first data is a first group of bits, which are included in the first data and have a first value, and the at least part of the second data is a second group of bits, which are included in the second data and have the first value,

wherein the changing the third data includes:

(a) initializing each value of bits included in the third data to the first value;

(b) changing each value of bits corresponding to the first group among bits included in the third data, which has been initialized in operation (a), to a second value;

(c) changing each value of bits corresponding to the second group among bits included in the third data, which has been changed in operation (b), to the second value; and

(d) changing each value of common bits among bits included in the third data, which has been changed in operation (c), to the first value, and

wherein the each common bit is a bit corresponding to bits that have the first value at the same position in both of the first group and the second group.

14. The method of claim 13 , wherein the non-volatile memory sequentially performs operations (a) through (d) in response to a single test mode command, which is output from the controller to control the test mode operation.

15. The method of claim 13 , wherein the non-volatile memory performs operations (a) through (d) in response to test mode commands, respectively, which are sequentially output from the controller to control the test mode operation.

16. The method of claim 10 , further comprising:

transmitting the data that is the same as the bit-wise logic operation data to the controller; and

counting the number of bits having a particular value in the data that is the same as the bit-wise logic operation data and generating a count value, using a counter.

17. The method of claim 10 , further comprising:

performing a bit-wise XOR operation on reference data and the data that is the same as the bit-wise XOR data using an XOR logic circuit comprised in the non-volatile memory; and

counting the number of bits having a particular value in data output from the XOR logic circuit and outputting a count value to the controller, using a counter comprised in the non-volatile memory.

18. The method of claim 17 , wherein the reference data is transmitted from the controller.

19. The method of claim 10 , wherein the non-volatile memory is a NAND flash memory.