PEKERIS a Maple package that redoes 1958 Chaim Leib Pekeris’ seminal calculations of the ground state energies of two electron atoms, on a 2010 computer. It accompanies an article by Christoph Koutschan and Doron Zeilberger (Posted May 26, 2010). The 1958 Pekeris-Accad-WEIZAC ground-breaking collaboration that computed ground states of two-electron atoms (and its 2010 redux). Summary: In order to appreciate how well off we mathematicians and scientists are today, with extremely fast hardware and lots and lots of memory, as well as with powerful software both for numeric and symbolic computation, it may be a good idea to go back to the early days of electronic computers and compare how things went then. We have chosen, as a case study, a problem that was considered a huge challenge at the time. Namely, we looked at C. L. Pekeris’s seminal 1958 work [Phys. Rev., II. Ser. 112, 1649–1658 (1958; Zbl 0082.44604)] on the ground state energies of two-electron atoms. We went through all the computations ab initio with today’s software and hardware.