The growing body of spectral observations of the extremely metal-poor (EMP) stars in the Galactic Halo provides constraints on theoretical studies of the chemical and stellar evolution of the early Universe. To calculate yields for EMP stars for use in chemical evolution calculations and to test whether such models can account for some of the recent abundance observations of EMP stars, in particular the highly C-rich EMP (CEMP) halo stars. We modify an existing 1D stellar structure code to include time-dependent mixing in a diffusion approximation. Using this code and a post-processing nucleosynthesis code we calculate the structural evolution and nucleosynthesis of a grid of models covering the metallicity range: -6.5<=[Fe/H]<=-3.0 (plus Z=0), and mass range: 0.85<=M<=3.0M_{sun}_, amounting to 20 stars in total.