... not open for extensions. (E.g. what I'd like to do is couple my Forth 8051 simulator to the microcontroller hardware and cosimulate them, using the actual 8051 source code.) One advantaqe of gEDA is that you can use multiple back ends, including LTSPICE (see http://www.brorson.com/gEDA/SPICE/). The mixed mode/mixed language kind of simulation you seem to be talking about is where...