ngspice vs SimEvents

ngspice is a free, open-source simulator for electric and electronic circuits described as netlists. It handles analog, digital, and mixed-signal designs, with models for active, passive, analog, and digital elements; model parameters can come from collections, manufacturers, or foundries. Its SPICE compatibility supports PSPICE or LTSPICE device model parameters and netlists for discrete circuits. For mixed-signal co-simulation, it supports Verilog blocks compiled with Verilator and, since ngspice-44, VHDL blocks using GHDL. The OSDI/OpenVAF interface connects Verilog-A compact device models without requiring programming on the ngspice side. It can also be built as a shared library or DLL for another application to control. Listed integrations include KiCad, Autodesk Fusion, and Python interfaces such as PySpice. ngspice does not include schematic entry: input is through the command line or files. The stable download page offers source archives and Windows binaries; Linux users are directed to their distributor or source compilation, and the project's own macOS release is unavailable there.

SimEvents is desktop software for modeling message-based communication and other event-driven processes. It uses a discrete-event simulation engine and component library, and can combine event-based models with Simulink time-based models for large hybrid systems. Blocks represent entity creation and destruction, queues, service times, routing, attributes, and event responses. Resource Pool, Resource Acquirer, and Resource Releaser blocks model resource allocation, while repeated simulations can support optimization. Analysis includes latency, throughput, packet loss, queue lengths, delays, and average service times. Users can simulate and debug models, inspect queue contents, visualize entity activity, and build custom visualization tools. Output statistics aggregate measures, and Sequence Viewer displays messages, events, and entities. MATLAB Discrete Event System and Discrete Event Chart blocks allow custom behavior. Listed applications include communication networks, software and hardware architectures, forecasting, capacity planning, and supply chain management. SimEvents requires MATLAB and Simulink, runs on Windows, Mac, and Linux, and has a 30-day trial with paid licensing.