Patent ID: 7099221

Claim:
A method of refreshing rows of memory cells in a dynamic random access memory in which operational memory cells in some of the rows are prone to errors, the method comprising: identifying the rows of memory cells that contain at least one operational memory cell that is prone to error by: writing data to the memory cells in the dynamic random access memory; retaining the data stored in the memory cells while the memory cells are refreshed; reading the data stored in the memory cells in the dynamic random access memory; and identifying each row of memory cells in which the data read from at least one memory cell in the row does not match the data written to each corresponding memory cell in the row, the act of identifying each row of memory cells in which the data read from at least one memory cell in the row does not match the data written to each corresponding memory cell in the row comprising: writing an error checking code to the memory cells in the dynamic random access memory along with the data written to the memory cells; reading the error checking code stored in the memory cells in the dynamic random access memory along with the data stored in the memory cells in the dynamic random access memory; and processing the read error checking code to identify each row of memory cells in which the data read from at least one memory cell in the row does not match the data written to each corresponding memory cell in the row; and refreshing the identified rows of memory cells at a rate that is faster than the rate at which other rows of memory cells are refreshed.