A digital scanning graphic monitor based on Apple Ⅱe microcomputer has been at work on the SINR SPM instead of storage oscilloscope. It can display the distribution graphics of trace elements within the micro-area. For data acquisition a dual channel A ID converter samples the X and Y scanning voltage whenever a signal is within a preset energy window and with proper delay. In order to improve the clearness of pictures by adjusting their contrast

four threshold levels with buffers have been set to store pictures at different 4evels. The other three buffers are used to store and restore pictures displayed on the screen. The scanning graphic can be enlarged or lessened when changing the scanning range. The signals which trigger the A/D converter can come from emitted X rays or secondary electrons.