Rịba ama amaokwu a dị n'okpuru ma zaa ajụjụ ahụ mgbe e mesịrị n'otu asụsụ ahụ dị ka amaokwu ahụ:  N'afọ 1977, Kọmpụta Kọmpụta Kọmpụta (CSRG) sitere na UC Berkeley mepụtara Berkeley Software Distribution (BSD), dabere na mbipụta nke isii nke Unix site na AT&T. Ebe ọ bụ na BSD nwere koodu Unix nke AT&T nwere, AT&T gbara akwụkwọ (USL v. BSDi) na mbido 1990s megide Mahadum California. Nke a belatara mmepe na nnabata nke BSD. N'afọ 1983, Richard Stallman bidoro ọrụ GNU na ebumnuche nke ịmepụta sistemụ arụmọrụ dị ka UNIX n'efu. Dịka akụkụ nke ọrụ a, o dere GNU General Public License (GPL). Ka ọ na-erule mmalite afọ ndị 1990, ọ fọrọ nke nta ka ọ bụrụ na e nwere ngwanrọ zuru ezu iji mepụta sistemụ arụmọrụ zuru ezu. Otú ọ dị, kernel GNU, nke a na-akpọ Hurd, enweghị ike ịdọta mbọ mmepe zuru oke, na-ahapụ GNU ezughi ezu. Na 1985, Intel wepụtara 80386, nke mbụ x86 microprocessor nwere usoro ntụziaka 32-bit na otu njikwa ebe nchekwa na paging. Na 1986, Maurice J. Bach, nke AT&T Bell Labs, bipụtara The Design of the UNIX Operating System. Nkọwa ikpeazụ a na-ekpuchi System V Release 2 kernel, na ụfọdụ atụmatụ ọhụrụ site na Release 3 na BSD.  Ajụjụ: Olee otú ọtụtụ software e nwere site na n'oge 1990s?
ihe fọrọ nke nta ka ọ bụrụ ngwanrọ zuru ezu iji mepụta usoro sistemụ zuru ezu