Abstract: The scanning tunneling microscope (STM)is a powerful instrument which provide surface topographic images down to the atomic scale and spectroscopic information on the surface density of electronic states. A computerized system based on the IBM Personal Computer Model XT or AT for STM control, data acquisition and display is presented. The high resolution digital-to-analog converter card and analog-to-digital converter card are used for the computer to generate the voltages applied to the STM piezoelectric elements and to measure the tunneling current. A high resolution graphics controller card is used for real-time display of the STM “images”. The software that performs the control, data acquisition and display of the STM has been written in FORTRAN and linded with some ASSEMBLER subroutines for the critical tasks in order to get a fast and compact executable module which works under DOS Version 3.2. Some images anaysis and display tool are included for a posterior image processing.