NAPA
A mixed‑signal circuit simulator kept by one engineer since 1997 — write a netlist, press Alt+R, watch it compile straight to C.
A compiler first, a simulator second.
NAPA turns a netlist — a plain‑text description of a circuit, written in its own small language — into optimized ANSI‑C. That C is compiled and run as a fast, cycle‑based simulator built for that one circuit alone. Nothing generic sits in the loop.
It handles analog and digital parts of the same system together: delta‑sigma modulators, switched‑capacitor filters, logic, FFTs, user‑defined C functions — with automatic type inference between analog (double) and digital (64‑bit integer) signals.
It is free, runs on 64‑bit Windows, and makes no network calls of its own.
Six lines, one filter.
A real file from NAPA's own test suite: white noise through an RC low‑pass, straight into a transfer‑function tool.
title "$F" header <napatool.hdr> fs 10.0e6 dvar R 1.0e6 dvar C 10.0e-12 node in noise 0.0 1.0 node out cell lpf "../lprc1.net" in R C
Current release — v4.60
- Simulate_460.zip~1.0 GB
- Installing NAPAPDF
- Short Introduction to NAPAPDF
- NAPA ReferencePDF
The distribution ships as one encrypted archive. The password sits alongside it in the same folder, as a plain text file — nothing to request, nothing to remember in advance.
All mimsy were the borogoves,
And the mome raths outgrabe. — Lewis Carroll, Jabberwocky
Invented words that still parse. A personal netlist language that still compiles. The domain kept the theme.