Abstract: The invention features a sort computer which interfaces with a sorting device in order to control the sorting of beads on a bead by bead basis. The invention further features novel methods for the directed synthesis of encoded libraries of oligomers, e.g., oligonucleotides, on beads. These methods allow the synthesis of libraries that are sufficiently large to permit complex genomic analyses to be carried out. New methods of using the encoded libraries also are described.