These cards give the element name and the numbers of the nodes to which the element is attached. Element cards begin with the name of the element, the first letter of which determines whether the element is a resistor, bipolar transistor, diode and so on. This is followed by the node connections and any parameters, for example the value of a resistor. Control Card - These cards specify options to the program and the analyses to be performed. Also device models are described in control cards.
All control cards begin with the character '.', as in the .END card.
By convention the node connected to ground, or the datum node, is numbered 0, Spice requires this convention to be followed. Each element of the circuit should then be named, noting that the first letter of the name determines the type of element, thus R denotes a resistance, C a capacitor. Following the name the node connections are given, and then the parameters specific to the circuit element. Models For the more complex elements, bipolar transistors, field effect transistors and diodes, many of the parameters will be the same for each element. The channel width and length however will depend on the individual transistor.