The use of acousto-optic and electro-optic signal processing for aiding the testing of high speed and/or high density VLSI circuits is introduced. Various VLSI testing scenarios that involve comparison of the chip output and the expected reference output are discussed. Two acousto-optic architectures are discussed that could be useful for recording and com-paring high speed digital data. Experimental proof-of-principle results are presented along with a prototype processor module. The acousto-optic and electro-optic implementation of a third architecture that is useful for comparing and compressing high speed digital data, is also discussed along with initial experimental results.