An apparatus provided with programmable scan chains includes a scan chain having a scan input port and a scan output port, a plurality of first I/O ports, an input port selector for selecting one of the plurality of first I/O ports to be coupled to the scan input port, a plurality of second I/O ports, an output port selector for selecting one of the plurality of second I/O ports to be coupled to said scan output port. Further, an apparatus provided with programmable scan chains includes N scan chains, each scan chain having a scan input port and scan output port, M first I/O ports, an input port selector for selecting N of the first I/O ports to be coupled to the N scan input ports, K second I/O ports, and an output port selector for selecting N of the second I/O ports to be coupled to the N scan output ports.