  We present ROBO, a model and its companion code for the study of the
interstellar medium (ISM). The aim is to provide an accurate description of the
physical evolution of the ISM and to set the ground for an ancillary tool to be
inserted in NBody-Tree-SPH (NB-TSPH) simulations of large scale structures in
cosmological context or of the formation and evolution of individual galaxies.
The ISM model consists of gas and dust. The gas chemical composition is
regulated by a network of reactions that includes a large number of species
(hydrogen and deuterium based molecules, helium, and metals). New reaction
rates for the charge transfer in $\mathrm H^+$ and $\mathrm H_2$ collisions are
presented. The dust contains the standard mixture of carbonaceous grains
(graphite grains and PAHs) and silicates of which the model follows the
formation and destruction by several processes. The model takes into account an
accurate treatment of the cooling process, based on several physical
mechanisms, and cooling functions recently reported in the literature. The
model is applied to a wide range of the input parameters and the results for
important quantities describing the physical state of the gas and dust are
presented. The results are organized in a database suited to the artificial
neural networks (ANNs). Once trained, the ANNs yield the same results obtained
by ROBO, with great accuracy. We plan to develop ANNs suitably tailored for
applications to NB-TSPH simulations of cosmological structures and/or galaxies.
