1. A mask-programmable logic device disposed on an integrated circuit and configured to facilitate the conversion of a pre-existing design of a source programmable logic device into the mask-programmable device, comprising: a plurality of mask-programmable logic resources disposed on a substrate of the integrated circuit; and a plurality of interconnection conductors coupled to the mask-programmable logic resources and disposed above the substrate for interconnecting the mask-programmable logic resources, wherein at least one of the plurality of mask-programmable logic resources comprises: at least one smart switch disposed on the substrate, the smart switch being programmable to perform a function of a configuration-related logic circuit of the pre-existing design of the source programmable logic device.