1-Qucs-code-analysis/1-Introduction.md

+# An anlysis of Qucs-GUI code base
+
+## A bit of context
+
+### Simulation backends and other supporting executables
+
+Qucs-gui relies on a few executables to carry it's job, I have identified these ones so far:
+- qucsator (simulation engine)
+- asco (optimisation engine)
+- ngspice (simulation engine)
+- xyce (simulation engine)
+- spiceopus (simulation engine)
+- octave (?)
+- admsXml (?model compilation, Verilog-A?)
+- qucsconv (?converter?)
+- qucsdigi (VHDL, digital simulation)
+- qucsdigilib (VHDL, digital simulation, wrapper around freehdl)
+- qucsveri (Verilog, digital simulation, wrapper around qucsconv)
+
+
+### Simulation domains
+
+Alltogether, Qucs and Qucs-S (aka. Spice4Qucs) support the following simulation domains, using different backends (
+See, eg. [Qucs-Spice documentation](https://qucs-help.readthedocs.io/en/spice4qucs/BasSim.html#other-forms-of-simulation)
+for more details)
+
+Digital:
+- Truth table
+- Time list
+
+Main analog simulation domains:
+- DC
+- AC
+- TRANsient
+
+Additional analog simulation domains:
+- Fourier
+- Distortion
+- Noise
+- Pole/Zero
+- Sensitivity
+- Harmonic balance
+
+Notes:
+- It is possible to run several simulation (domains) at once, but not all combinations are valid and/or supported.
+- Different simulation backend support different simulation domains.
+- At the time of this writing, i do not know to which extent the backends are (un)compatible when it comes to "component models and properties".
+