Memory controller and method of controlling memory

1. A memory controller that controls a plurality of memories, the memory controller comprising:

an estimating unit that counts a number of occurrences of uncorrectable errors obtained as a result of an error checking when there is a request for data, the memory controller controlling the plurality of memories each of which is a dual memory having an independent address line, the dual memory not recognizing an occurrence of an error on the address line, the estimating unit estimating an error has occurred on the independent address line for data related to the request when the number of occurrences of the uncorrectable errors exceeds a first predetermined threshold; and

a control unit that generates error data when it is estimated that an error has occurred on the independent address line and disables one independent address line of the dual memory by switching the data output from the memory controller from data related to the request to the generated error data.

2. The memory controller according to claim 1 , wherein the estimating unit estimates whether an error has occurred on the independent address line based on a result of an error checking executed for the memory connected to the memory controller.

3. The memory controller according to claim 1 , wherein the estimating unit estimates whether an error has occurred on the independent address line based on a result of an error checking executed for each of a plurality of connected memories.

4. The memory controller according to claim 1 , further comprising a determining unit that re-executes, when it is estimated that an error has occurred on the independent address line, the error checking, and determines whether an error has occurred on the independent address line based on a result of the re-executed error checking, wherein

the control unit switches, when it is determined that an error has not occurred on the independent address line based on the re-executed error checking, data output from the memory controller from the generated error data to the data related to the request, and controls the memory.

5. The memory controller according to claim 4 , wherein the determining unit counts the number occurrences of no errors obtained as the result of the re-executed error checking, and determines that an error has not occurred on the independent address line when the number of occurrences of the no errors exceeds a second predetermined threshold.

6. A memory controller that controls a plurality of memories each of which is a dual memory having an independent address line, the memory controller comprising:

an estimating unit that counts a number of occurrences of uncorrectable errors obtained as a result of an error checking when there is a request for data, the estimating unit estimating an error has occurred on the independent address line for data related to the request when the number of occurrences of the uncorrectable errors exceeds a first predetermined threshold;

a control unit that generates error data when it is estimated that an error has occurred on the independent address line and disables one independent address line of the dual memory by switching the data output from the memory controller from data related to the request to the generated error data; and

a changing unit that changes the first predetermined threshold.

7. A memory controller that controls a plurality of memories each of which is a dual memory having an independent address line, the memory controller comprising:

an estimating unit that counts a number of occurrences of uncorrectable errors obtained as a result of an error checking when there is a request for data, the estimating unit estimating an error has occurred on the independent address line for data related to the request when the number of occurrences of the uncorrectable errors exceeds a first predetermined threshold;

a control unit that generates error data when it is estimated that an error has occurred on the independent address line and disables one independent address line of the dual memory by switching the data output from the memory controller from data related to the request to the generated error data;

a determining unit that re-executes, when it is estimated that an error has occurred on the independent address line, the error checking, and determines whether an error has occurred on the independent address line based on a result of the re-executed error checking; and

a changing unit that changes a second predetermined threshold, wherein

the control unit switches, when it is determined that an error has not occurred on the independent address line based on the re-executed error checking, data output from the memory controller from the generated error data to the data related to the request, and controls the memory, and

the determining unit counts the number occurrences of no errors obtained as the result of the re-executed error checking, and determines that an error has not occurred on the independent address line when the number of occurrences of the no errors exceeds the second predetermined threshold.

8. A method of controlling a plurality of memories in a system each of which is a dual memory having an independent address line, the method comprising:

counting a number of occurrences of uncorrectable errors obtained based on a result of an error checking when there is a request for data in the system, the dual memory not recognizing an occurrence of an error on the address line;

estimating the error has occurred on the independent address line for data related to the request when the number of occurrences of the uncorrectable errors exceeds a first predetermined threshold;

generating, when it is estimated that an error has occurred on the independent address line, error data of the data related to the request; and

controlling the memory to disable data from one independent address line of the dual memory by switching the data to be output from data related to the request to the generated error data.

9. The method according to claim 8 , wherein the estimating includes estimating whether an error has occurred on the independent address line based on a result of an error checking executed for each of dual memories.

10. The method according to claim 8 , further comprising:

re-executing, when it is estimated that an error has occurred on the independent address line, the error checking;

determining whether an error has occurred on the independent address line based on a result of the re-executed error checking; and

switching, when it is determined that an error has not occurred on the independent address line, data to be output from the generated error data to the data related to the request.

11. The method according to claim 10 , wherein the determining includes

counting the number occurrences of no errors obtained as the result of the re-executed error checking, and

determining that an error has not occurred on the independent address line when the number of occurrences of the no errors exceeds a second predetermined threshold.