  We present extensive evolutionary models of stars with initial
zero-metallicity, covering a large range of initial masses (i.e. 0.7 <= M <=
100 Msun). Calculations are carried out at constant mass, with updated input
physics, and applying an overshooting scheme to convective boundaries. The
nuclear network includes all the important reactions of the p-p chain,
CNO-cycle and alpha-captures, and is solved by means of a suitable
semi-implicit method. The evolution is followed up to the thermally pulsing AGB
in the case of low- and intermediate-mass stars, or to the onset of carbon
burning in massive stars. The main evolutionary features of these models are
discussed, also in comparison with models of non-zero metallicity. Among
several interesting aspects, particular attention has been paid to describe: i)
the first synthesis of 12C inside the stars, that may suddenly trigger the
CNO-cycle causing particular evolutionary features; ii) the pollution of the
stellar surface by the dredge-up events, that are effective only within
particular mass ranges; iii) the mass limits which conventionally define the
classes of low-, intermediate-, and high-mass stars on the basis of common
evolutionary properties, including the upper mass limit for the achievement of
super-Eddington luminosities before C-ignition in the high-mass regime; and iv)
the expected pulsational properties of zero-metallicity stars. All relevant
information referring to the evolutionary tracks and isochrones is made
available in computer-readable format at http://pleiadi.pd.astro.it .
