We present a computer simulation study of simple models of alkali metal-alkali halide melts M-x[MX](1-x). The geometries are modeled using the primitive model of hard spheres, the electronic structure is described by a tight-binding Hamiltonian including the crucial component of Madelung potential fluctuations. Electronic defects like F centers are treated by a novel variational ansatz. We focus on the computation of experimentally measured quantities like the optical absorption or the electronic conductivity and the paramagnetic susceptibility as a function of x. Despite the simplicity of the underlying model, simulation and experiment are in good agreement in the entire region from nonmetallic to metallic states.