A pump system selectably and dynamically controls the flow rate of a fluid being delivered to a patient's body over a wide range of flow rates. The pump system includes an infusion tubing, a pumping mechanism, a motor drive assembly in mechanical communication with the pumping mechanism, a user input control, and an electronic controller in electrical communication with and at least partially controlling the motor drive assembly. The electronic controller include a digital signal processing controller in electrical communication with the motor drive assembly that is configured to receive a signal from the user input control and to cause power to be supplied to the motor drive assembly in response at least partially to the signal from the user input control. The pump system may selectably deliver fluid at rates from about 1 milliliter per hour to at least about 3000 milliliters per minute.