A redundancy architecture for improving the throughput of testing and repairing the semiconductor memory after packaging. A memory device is composed of a memory cell array including memory cells and first redundant cells, a data comparator comparing read data received from the memory cell array with anticipated data provided by an external tester to produce a data mismatch signal, a redundancy mapping circuit responsive to the data mismatch signal for detecting a defective address of the memory cell array, a nonvolatile memory storing the detected defective address, and a redundancy circuitry repairing the memory cell array by replacing ones of the memory cells associated with the defective address with the first redundant cells.