During the early 1970's there was often heated debate over the quality of analytical performance attainable with Energy Dispersive (ED) systems using solid state detectors. Many scientists, particularly the more practical ones, were convinced that only WDX was reliable; while those with perhaps more imagination were convinced EDX was the future in microanaiysis. At that time, both groups were right.

EDX has seen remarkable improvement since those early days. At that time ED spectrometers were limited to analysis of elements above atomic number 10, and state-of-the-art resolution was improving to about 155 eV at Mn. Overlaps were handled strictly in quantitative analysis routines and even then only by use of simple overlap factors. Wavelength Dispersive (WD) spectrometers, although slow and difficult to operate, were required for light element analysis, to perform analyses when overlaps were present or suspected, and to detect trace elements.