Microfabricated devices containing arrays of nucleic acid hybridization sites, known as genosensors, are being developed for a variety of uses in genomic analysis. A great deal of the overall genosensor development effort involves optimization of experimental conditions in the actual use of genosensors. Here we describe a "low-tech" form of genosensor technology, involving arrays of oligonucleotides on glass microscope slides, which can be used to define optimal operating conditions and to develop applications of hybridization arrays in genome mapping and sequencing. In addition, we describe a porous silicon genosensor, which can be operated in a flowthrough mode, and discuss its advantages over current flat-surface designs. Porous silicon genosensors containing arrays of DNA fragments offer several unique capabilities in genome analysis.