Editing SPICE (section)

===Input and output: Netlists, schematic capture and plotting===
SPICE2 takes a text [[netlist]] as input and produces line-printer listings as output, which fits with the computing environment in 1975.  These listings are either columns of numbers corresponding to calculated outputs (typically voltages or currents), or line-printer [[ASCII art|character "plots"]]. SPICE3 retains the netlist for circuit description, but allows analyses to be controlled from a [[command line interpreter|command-line]] interface similar to the [[C shell]]. SPICE3 also added basic [[X Window System|X]] plotting, as [[UNIX]] and engineering [[workstation]]s became common.

Vendors and various free software projects have added [[schematic capture]] [[Frontend and backend|frontends]] to SPICE, allowing a [[schematic diagram]] of the circuit to be drawn and the netlist to be automatically generated and transferred to various SPICE backends. Also, [[graphical user interface]]s were added for selecting the simulations to be done and manipulating the voltage and current output vectors. In addition, very capable graphing utilities have been added to see waveforms and graphs of parametric dependencies. Several free versions of these extended programs are available.