  In this paper, I will describe the features of the numerical code CUBA, aimed
at the solution of the radiative transfer equation in a cosmological context.
CUBA will be soon available for public use at the URL
http://pitto.mib.infn.it/~haardt/, allowing for several user-supplied input
parameters, such as favourite cosmology, luminosity functions, Type II object
evolution, stellar spectra, and many others. I will also present some new
results of the UV/X-ray cosmic background as produced by the observed
populations of QSOs and star forming galaxies, updating and extending our
previous works. The background evolution is complemented with a number of
derived quantities such as the ionization and thermal state of the IGM, the
HeII opacity, the HI and HeII ionization rates, and the HI, HeII and Compton
heating rates.
