An automated data acquisition system is under continuing development for the Vacuum Generators HB-501 ultrahigh-resolution dedicated scanning transmission electron microscope (STEM) to overcome the limitations of commercial systems for concurrent data acquisition and processing algorithms. As part of the new system, a data acquisition and analysis program, called Desk Top Spectrum Analyzer and X-Ray Database (DTSA), has been developed for the Macintosh II (and higher) class of Apple computers. Data acquisition is accomplished with a specially modified, commercial, NuBus-compatible I/O processor and custom-designed acquisition and control software routines. A patent (U.S. Patent No. 5,299,138), held jointly by the NIH and the NIST, was issued for this analytical tool in March 1994. The DTSA is available from the Office of Standard Reference Data (OSRD), National Institute of Standards and Technology, for a modest fee. A copyright has also been obtained by the OSRD.