To determine how nucleotide bases are arranged, most sequencing machines break a DNA strand apart and replicate it, amplifying it by several orders of magnitude. Computers suss out the nucleotide arrangements using a variety of methods, from dyes to other chemicals. Take the forthcoming $1,000-per-genome Ion Proton chip, for instance. It attaches DNA fragments to microscopic beads and spins them in microwells on a semiconductor chip. The wells are flooded with each of the DNA nucleotides, and the machine looks for matchups. When there's a match, a positive hydrogen ion is released, and algorithms interpret the resulting voltage change to determine which bases matched, thereby building a chart of base arrangements.