In 1992 I implemented John Holland's Echo program in C for UNIX machines using X windows graphics. Echo is easiest to get going on a SUN Sparc workstation as it includes compiled widget libraries from various places.

*The Echo home page, maintained by Peter Hraber (
*Get the Echo source.
*A postscript introduction to Echo (Santa Fe Institute TR 93-12-074). The same thing, but in friendly clickable html courtesy of Peter Hraber.
*A paper on species abundance patterns in Echo:
Forrest, S. and T. Jones. 1994.
Modeling complex adaptive systems with Echo.
Pages 3-21 in R.J. Stonier and X.H. Yu, (eds.) Complex Systems: Mechanisms of Adaptation. IOS Press, Amsterdam.

This paper is available on-line in HTML.

Terry Jones (terry <AT>