Machines having a boom or arm pivotally disposed thereon wherein the length of the boom or arm and the angle thereof with respect to a reference plane are adjustable by means of actuators are well known. However, it is extremely difficult, if not impossible, to simultaneously control the actuators in a coordinated fashion to move the end of the boom or arm in a straight line path. In order to overcome this problem, a boom control system for a boom according to the present invention controls the actuators in either of two modes of operation, the first mode of operation comprising independent control over each actuator to afford polar coordinate operation and the second mode of operation comprising synchronized control over the actuators so that the end of the member may be moved in a straight line. Means are provided for manually selecting one of the two modes of operation. Means may be provided for calculating the amount of remaining horizontal throw of the boom or arm when a command to move same is issued.