This paper presents a new test data compression technique based on a compression code that uses exactly nine code-words. In spite of its simplicity, it provides significant reduction in test data volume and test application time. In addition, the decompression logic is very small and independent of the precomputed test data set. Our technique leaves many don?t-care bits unchanged in the compressed test set, and these bits can be filled randomly to detect non-modeled faults. The proposed technique can be efficiently adopted for single- or multiple-scan chain designs to reduce test application time and pin requirement. Experimental results for ISCAS?89 benchmarks illustrate the flexibility and efficiency of the proposed technique.