Nucleosynthesis below A=100 in massive stars

The production of nuclei up to and including the weak s-process component a t A approximate to 60-90 is calculated for all stages of stable and explosi ve nuclear burning in stars of 15, 20, and 25 M. with initial solar metalli city. An extended nuclear reaction network of 480 isotopes is employed alon g with approximately two dozen recent revisions to key nuclear reaction rat es. As noted previously, the new rates suggest a greatly diminished product ion of O-17 and O-18 in massive stars. Ne-22 is also moderately enhanced. W e find that a combination of preexplosive s-process, gamma -process, and (m ild) r-processes in massive stars gives a consistently solar production of almost all isotopes from mass 64 through 90. However, even after the late s tages of evolution are complete and the explosion is over, this same group of elements is overproduced compared to what is needed for the Sun, especia lly in the 25 M. model.