Abstract: An improved gas delivery system and method delivers a sequence of pulses of prescribed amounts of at least two gases to a process chamber of a process tool in accordance with a predetermined recipe of steps of a gas delivery process. The system comprises: a plurality of channels, each including a control valve connected so as to control each pulse of gas flowing through the corresponding channel into the process chamber of the process tool; and an exhaust valve for controlling the pressure within the process chamber, the exhaust valve including a valve controller for controlling the operation of the gas delivery system including the control valves and the exhaust valve in accordance with the predetermined recipe of steps.