This project is the comprehension redesign of the neural simulation toll referred to as GENESIS (GEneral NEural SImulation System). GENESIS was developed initially as part of the P.I.'s ongoing efforts to build realistic models of nervous systems. GENESIS has been made available for use to laboratories outside Caltech for research and education, and has become an important tool for the computational neuroscience community. The overall design objective for the GENESIS project is to provide neurobiologists with a powerful tool for simulating neruobiological systems, while at the same time promoting the interactions between different modeling efforts. We will concentrate on two areas: first we will continue to provide ongoing user support. This includes on-line services, continued development of documentation, bug fixes, and promotion of collaborations between GENESIS users and between GENESIS developers. The second major focus of our activities will be the redesign of GENESIS itself. The basic software design of the project has not changed substantially since its inception in 1986. It is now time to completely redesign GENESIS to provide far more efficient portability across platforms free extensibility and exchange of code, flexibility lump missing parameters and compartments, and provide granularity along multiple axes. Achieving these goals should result in a move useful, more easily federated system which is far less expensive to extend and maintain. The redesign is beginning by first taking a parallel systems view point, rather than starting with a sequential platform and later parting to parallel. This work is supported by the Computational Neuroscience program, and the neuroscience's cluster (all in Bio). This effort will focus on both support for parallel architectures as well as new graphics languages.