Ngspice can simulate numerical device models for diodes and transistors in two different ways, either through the integrated DSIM simulator or interfacing to GSS TCAD system. DSIM is an internal C-based device simulator that is part of the CIDER simulator, the mixed-level simulator based on SPICE3f5. CIDER within ngspice provides circuit analyses, compact models for semiconductor devices, and one- or two-dimensional numerical device models.