Abstract: A controller for solvent programmer apparatus that produces programmed solvent mixtures for introduction to a liquid chromatographic analyzer. Under the direction of the controller, the solvent programmer accesses first and second solvents during a defined cycle of operation and proportions the solvents on the basis of the time within the cycle of operation that each solvent is accessed. The controller has a first counter that defines the cycle of operation and a second counter that is preset at the beginning of a cycle to a value representative of the percentage of the first solvent that is to be in a solvent mixture produced during the cycle. The second counter is then counted down.