SEMICONDUCTOR MEMORY DEVICES, MEMORY SYSTEMS AND METHODS OF OPERATING SEMICONDUCTOR MEMORY DEVICES

A semiconductor memory device includes a memory cell array including a plurality of dynamic memory cells, an ECC engine configured to correct at least one error in a read data from the memory cell array, and a test circuit which performs a test on the memory cell array in a test mode of the semiconductor memory device by writing a test pattern data in the memory cell array and by reading, from the memory cell array, test result data corresponding to the test pattern data. When the test result data includes at least one error bit, the test circuit subtracts a second number from a first number of the at least one error bit and is configured to output the subtracted result to an outside of the semiconductor memory device. The second number corresponds to a number of error bits that the ECC engine is capable of correcting.