Electronic plural component proportioner

An electronic apparatus is provided for dispensing plural component materials having first and second (and optionally third) components and a desired ratio between the components. The apparatus has first and second reciprocating pumps, each of the pumps being connected to a source of one of said components, first and second reciprocating drivers, each driver being connected to drive one of the pumps and forming a driver-pump set, a position sensor attached to each driver-pump set, each position sensor outputting increments of resolution corresponding to a fixed volume being pumped by the driver-pump set to which it is connected, and a controller attached to the drivers and the position sensors to alternately move one of the driver-pump sets one said increment and the other of the driver-pump sets the product of one increment and the ratio.