A computerized system for scanning tunneling microscope control, data acquisition, and display is presented. It is based on the IBM Personal Computer Model XT or AT. An IBM Data Acquisition and Control Adapter card is used for the PC to control the electronic equipment and to measure the voltages applied to the three STM piezoelectric elements and the tunneling current. An IBM Professional Graphics Controller card is used for real-time display of the STM "images." The software has been designed in a modular way to allow the replacement of these cards and other improvements to the equipment. A discussion of performance (scanning speed and size of images) is included. Some image analysis and display tools are included for a posteriori image processing.