New simulation software combines Editor Windows for convenient modeling and file manipulation with a Command Window that automatically switches to full-screen color graphics while a simulation runs. Under Windows 95, the new program preempts the CPU, so that Windows does not compromise solution speed during the time-critical simulation runs. Windows multitasking works at all other times. Extra-fast runtime compilation and Pentium-optimized machine code let you quickly try and compare different models programmed in multiple editor windows. You can also program your own special dialog windows for data entry, model changes, and note keeping. Large problems can include up to 6000 first-order differential equations, plus neural networks and fuzzy logic. As an example, we solve the telegrapher's partial differential equation (delay-line equation) by the method of lines. We solve thousands of simultaneous differential equations first in scalar form and then using DESIRE's compact vector notation.