Is anyone aware of any tools to prepare these nice ASCII art schematics?

I'm sure I could do it with rectangular cut and past in Jed or Emacs,
which both run on various platforms, once I had a library of parts.
Has anyone got such a library?

--
James Cameron                                    (cameron@stl.dec.com)
Digital Equipment Corporation (Australia) Pty. Ltd. A.C.N. 000 446 800