Tbe AP/C control computer is a specially designed, high speed, serial, binary, general-purpose machine with approximately 2000 words of memory. Although the machine is basically a general-purpose computer, in includes special facilities for communicating with the operator of the AP/C Stereoplotter for inputs from the operator’s handwheels and footwheel, and for outputs to servomechanisms on the AP/C viewing unit and coordinatograph. A complete set of programs for inner, relative and absolute orientations and for plotting operations is provided. In addition, the computer may be used for general-purpose computing when not required for plotting. In speed and versatility it is superior to most medium-size commercial computers.