INTRODUCTION This Data Item@ No. 97023@ describes the installation details@ hardware requirements and configuration details for OSMEC@ a general-purpose mechanism design program. The configuration details of associated printers and plotters are also provided. OSMEC can model plane mechanisms composed of links@ pivoted and sliding joints@ gear trains and springs and cam-driven mechanisms and can interface with the cam design program OSCAM (see Reference 1). The program is menu driven@ has extensive on-line help and can be used to design mechanisms for applications involving high speeds and large forces. OSMEC displays static and animated drawings of a mechanism and graphs and tables of positions of points@ angles of links@ linear and angular velocities and accelerations@ driving and bearing forces and drive torque. The dimensions@ masses@ moments of inertia and load forces can be altered easily and quickly and the effects of these alterations are immediately analysed and displayed. Hard copy of any display can be sent to a plotter or printer@ or converted to a variety of formats (including HPGL) for use in other applications. OSMEC can export a DXF file to CAD software. OSMEC allows loads to be applied to any link in a mechanism as external forces/torques or using linear/torsion springs of all types. Inertial effects may also be included. An extensive library of mechanism models representing the majority of planar linkages found in practice is included. A user manual for OSMEC is described in an associated Data Item@ No. 97026 (see Reference 2).