Abstract: Physical or off-chip interfaces may be selectively bypassed in a boundary scan chain. A bypass control signal may be produced that indicates whether to bypass a selected one of the interfaces. In response to a first state of a bypass control signal, a multiplexer may couple the scan chain output of an interface boundary scan cell to the scan chain input of a successor boundary scan cell of the interface boundary scan cell. In response to a second state of the bypass control signal, the multiplexer may couple the scan chain output of a predecessor boundary scan cell of the interface boundary scan cell to the scan chain input of the successor boundary scan cell, bypassing the interface boundary scan cell.