Memory device and control method of memory device

1. A memory device, comprising:

a memory including a first port and a second port, the memory being configured to be accessed through the first port and the second port;

an error check and correct encoding circuit configured to apply an error check and correct code to data and to write the data and the error check and correct code into the memory through the first port;

an error check and correct decoding circuit configured to receive the data and the error check and correct code read from the first port, and corrects the data received when an error in the data received is detected based on the error check and correct code received; and

a control circuit configured not to write the data corrected and the error check and correct code into the memory through the second port when the error is detected and a current access address and a previous access address to the memory through the first port are the same, and to write the data corrected and the error check and correct code into the memory through the second port when the error is detected and the current access address and the previous access address to the memory through the first port are different.

2. The memory device according to claim 1 ,

wherein when output data of the first port of the memory has been changed, the error check and correct decoding circuit checks for an error in the output data, and sets an error flag when an error is detected and resets the error flag when no error is detected, and

wherein the control circuit writes, based on the error flag, the data corrected and the error check and correct code into the memory through the second port.

3. The memory device according to claim 2 , wherein when write into the memory is instructed, the memory receives the data and the error check and correct code from the error check and correct encoding circuit through the first port, the data received and the error check and correct code received are written into the memory, and the memory outputs, from the first port, the data received and the error check and correct code received, and

wherein the control circuit writes the data corrected and the error check and correct code into the memory through the second port when the error flag is in a set state, and does not write the data corrected and the error check and correct code into the memory through the second port when the error flag is in a reset state.

4. The memory device according to claim 3 , further comprising:

a delay circuit that delays the data and the error check and correct code outputted from the error check and correct encoding circuit, and outputs the data delayed and the error check and correct code delayed to the memory through the second port.

5. The memory device according to claim 2 ,

wherein when write into the memory is instructed, the memory receives the data and the error check and correct code from the error check and correct encoding circuit through the first port, the data received and the error check and correct code received are written into the memory, and the memory does not output, from the first port, the data received and the error check and correct code received but keeps the output data of the first port, and

wherein the control circuit writes the data corrected and the error check and correct code into the memory through the second port when the error flag has been changed from a reset state to a set state, and does not write the data corrected and the error check and correct code into the memory through the second port when the error flag keeps the set state.

6. The memory device according to claim 5 , further comprising:

a delay circuit that delays the data and the error check and correct code outputted from the error check and correct encoding circuit, and outputs the data delayed and the error check and correct code delayed to the memory through the second port.

7. The memory device according to claim 2 ,

wherein the memory is a first-type or second-type memory,

wherein when write into the first-type memory is instructed, the first-type memory receives the data and the error check and correct code from the error check and correct encoding circuit through the first port, the data received and the error check and correct code received are written into the first-type memory, and the first-type memory outputs, from the first port, the data received and the error check and correct code received, and

wherein when write into the second-type memory is instructed, the second-type memory receives the data and the error check and correct code from the error check and correct encoding circuit through the first port, the data received and the error check and correct code received are written into the second-type memory, and the second-type memory does not output, from the first port, the data received and the error check and correct code received but keeps the output data of the first port,

wherein the memory device further comprises an identification circuit that identifies which one of the first-type memory and the second-type memory the memory is, on the basis of the output data of the first port of the memory and output data of the error check and correct encoding circuit,

wherein when the memory is the first-type memory, the control circuit writes the data corrected and the error check and correct code into the first-type memory through the second port when the error flag is in a set state, and does not write the data corrected and the error check and correct code into the first-type memory through the second port when the error flag is in a reset state, and

wherein when the memory is the second-type memory, the control circuit writes the data corrected and the error check and correct code into the second-type memory through the second port when the error flag has been changed from the reset state to the set state, and does not write the data corrected and the error check and correct code into the second-type memory through the second port when the error flag keeps the set state.

8. The memory device according to claim 7 , further comprising:

a delay circuit that delays the data and the error check and correct code outputted from the error check and correct encoding circuit, and outputs the data delayed and the error check and correct code delayed to the memory through the second port.

9. A control method of a memory device, the memory device comprising:

a memory having a first port and a second port, the memory being configured to be accessed through the first port and the second port;

an error check and correct encoding circuit configured to apply an error check and correct code to data and to write the data and the error check and correct code into the memory through the first port; and

an error check and correct decoding circuit configured to receive the data and the error check and correct code read from the first port, and corrects the data received when an error in the data received is detected based on the error check and correct code received,

the control method, comprising:

not writing, by a control circuit, the data corrected and the error check and correct code into the memory through the second port when the error is detected and a current access address and a previous access address to the memory through the first port are the same; and

writing, by the control circuit, the data corrected and the error check and correct code into the memory through the second port when the error is detected and the current access address and the previous access address to the memory through the first port are different.