Abstract: A testing system selectively activates products of a semiconductor integrated circuit device mounted on a burn-in board, supplies test data signals to the products to see whether or not a defective product is mixed into the products, and a power distributor incorporated in the testing system supplies electric power only to the activated products so that non-activated products do not affect the test data signals.

Abstract: A high-speed pattern generator includes a plurality of arithmetic and logic units (ALUs) which are n in number and have m-bit outputs, n registers receptive as inputs as outputs from the ALUs, and n-bit shift registers which are m in number, each ALU and connected register being unitized and coupled to the shift registers. The outputs of the registered input data are applied to the ALUs. The unitized ALUs and registers produce outputs applied in the same sequence to bits of the shift registers, which are responsive to clock pulses to generate a pattern output at a high speed.