With the miniaturization of the diffusion process, the leak current per transistor tends to increase and the number of transistors per die tends to become larger, thus rendering more difficult the discrimination through the absolute value of IDDQ (Quiescent power supply current) that is required to detect defects on VLSI (Very Large Scale Integration). On the other hand, scan patterns convenient for their logical quality improvement are widely used. When adopting such a scan pattern and measuring the IDDQ, one finds that the measured values do not fluctuate greatly. In this paper, we will present a method of determining good and defective dies by making an approximation of this distribution using a gamma distribution and we will demonstrate the efficiency of our method through corroborative results.

multiple instructions per clock cycle, there are at least four This paper describes a VLSI superscalar processor architecture which can sustain very high performance in numericai applications. The architecture performs instructionlevel scheduling statically by the compiler, and performs outof-order issuing and executing of instructions to decrease the stall on the pipelines that dynamically occurs in execution. In this architecture, a pair of instructions are fetched in every clock cycle, decoded simultaneously, and issued to corresponding execution pipelines independently. For ease of instruction-level scheduling by the compiler, the architecture provider: -i) rimultaneoun execution df almost all pairs of instructions including Store-Stare pair and Load-Store pair, ii) simple, low-latency, and easily-paired execution pipeline structure, and iii) high-capacity muiti-ported floating point registers and integer registers. Enhanced performance by the dynamic decrease of the pipeline hazards is achieved by i) efficient data dependency resolution with novel Directly Tag Compare (DTC) method, ii) non-penalty branch mechanism and simple control dependency resolution, and iii) large data transfer ability by the pipelined data cache and 128 bit wide bus bandwidth. An efficient data dependency resolutioi mechanism, which is realized by using the novel DTC method, synchronized pipeiine operation, and data bypassing network, permits out-of-order instruction issuing and execution. The idea of DTC method is similar to that of dynamic data-flaw architecture with tagged token. The non-penalty branches are realized by three techniques, delayed branch, LOOP instruction that executer counter decrement, compare, and branch in one clock cycle, and non-penalty conditional branch with predicted condition codes. These 'techniques contribute to the decrease of the pipeline stalls occurring at run time. The architecture can achieve 80MFLOPS/80MIPS peak performance at 4OMHz clock and sustain 1.4 to 3.6 times higher performance of simple Multiple Function Unit (MFU) type RISC processors by taking advantage of these techniques.