Abstract: In a hydraulically powered pipe handling system, a general purpose digital computer is used to control the operation of hydraulically powered racker arms as well as the various auxiliary functions involved in vertical piperacking operations. The manual pipe-racking system (that is, that which is hydraulically powered and under the control of one or more operators) is retained, the computer controlled mode of operation being an alternative system present in the overall design.There is provided to the operator, while the system is in its automatic mode of operation, visual indication of length of drill string, depth of hole, depth of drill bit and composition of the drill string, including number and type of pipe lengths making up the drill string.