Abstract: A parallel operation linear feedback shift-register (LFSR) that generates random test patterns or creates a signature that represents the response of a device under test at ultra high speed using low speed components and/or a slow rate clock. The apparatus is comprised of: a register connected to an external clock, and a plurality of combinatorial logic networks sequentially connected, the last of which drives the register which in turn feeds back into the first of the combinatorial logic networks. Each of the combinatorial networks provides a pseudo-random pattern which are then outputted in parallel, thereby creating a high speed data flow. By providing additional data inputs to the combinatorial networks, the pseudo-random patterns become the signature of the input data.