Title of program: DECOMP (nitrogen DECOMPression mod-Nature of the physicalproblem ule) DECOMP models multi-tissue nitrogen transport in divers breathing compressed air (80% N 2 and 20% 02). Repetitive Catalogue number: AAFO and multi-level (depth and time) activities are traced continuously in time. Computed nitrogen pressures are compared with Program obtainable from: CPC Program Library, Queen's Uni-critical values used to fabricate the US Navy air tables. Lxversity of Belfast, N. Ireland (see application form in this trapolation of critical nitrogen pressures to altitude is effected issue) with an exponential barometer equation for air. Critical ratios (nitrogen pressure/ambient pressure) are also tabulated. Computer: Cray iS, Cray XMP, CDC 7600 Method of solution Programming language: Fortran IV DECOMP employs analytic solutions to the transfer rate equations to predict nitrogen tensions in tissues of arbitrary half-life. Operating system: CTSS In repetitive, multi-level applications, continuous tensions at the end of one stage form the initial values for the following High speed storage required: 404162B stage. Ascent, or descent, rates can be used with an averaging technique to transport nitrogen between stages. The diffusion Number of bits in a word: 64 equation used to transport nitrogen treats tissues as uniform (bulk) media. Peripherals used: terminal, printer and graphics server Running time Number of lines in combined program and test deck: 198 Calculations for six tissues in a 10 level excursion require less than a second.