A first example is available as a compacted 7z archive. It contains the source code of a controlling application, as well as its compiled executable and ngspice.dll (for MS Windows). As the input circuit an inverter chain has been divided into three parts. Three ngspice shared libraries are loaded, each simulates one partition of the circuit. Interconnections between the partitions are provided via a callback function. The simulation time is synchronized among the three ngspice invocations by another callback function.