AUTODYN - an interactive non-linear dynamic analysis program for microcomputer through supercomputers. AUTODYN uses a two dimensional coupled finite difference approach similar to the one described by Cowler and Hancock (1979). Both translational and axial symmetry are treated. The scheme allows alternative numerical processors to be selectively used to model different components/regions of a problem. Finite difference grids operated on by these processors can be coupled together in space and time to efficiently compute structural (or fluid-structure) interactions. AUTODYN currently includes a Lagrange processor for modeling solid continua and structures, an Euler processor for modeling fluids and the large distortion of solids, an ALE (Arbitrary Lagrange Euler) processor for specialized flow models and a shell processor for modeling thin structures. At present, all four processors use explicit time integration but implicit options will be added to the Lagrange and ALE processors in the near future. Material models are included for solids, liquids and gases (including HE detonation products).