 BIST is accomplished with a multiple-input signature register (MISR or MSR), which is a type of LFSR.A standard LFSR has a single XOR or XNOR gate, where the input of the gate is connected to several "taps" and the output is connected to the input of the first flip-flop.A MISR has the same structure, but the input to every flip-flop is fed through an XOR/XNOR gate.