ABSTRACT We here describe SNNS, a neural network simulator for Unix workstations that we have been developing at the Universitat Stuttgart, Germany. Our network simulation environment is a tool to generate, train, test and visualize artificial neural networks. The simulator consists of three major components: a simulator kernel that operates on the internal representation ofthe neural networks, a graphical user interface based on X-Windows to interactively construct and change small neural nets,:ind a compiler to generate the internal representation of large neural networks from a high level network description language.Keywords: connectionism, neural networks, network simulators, network description language 1. INTRODUCTION AND MOTIVATION SNNS (Stuttgart Neural Network Simulator) is an efficient and portable neural network simulation environment for Unixworkstations that we have been developing at the Institute for Parallel and Distributed High Performance Systems, Universitht Stuttgart, Germany. It is an efficient software tool to generate, train, test and visualize artificial neural networks. The