The simulator's user interface is implemented as a Java applet embedded in a web page, so it can be used online [1]. On loading this page, EniacApplet is started, the main interface class. By clicking the variuos unit buttons, the user can take a closer look at the contents of the variuos units of the ENIAC simulator, load example programs, write new ones (see Section 5), and start a calculation.
![\includegraphics[width=\textwidth]{pictures/main_screen.ps}](img9.png)