▁Come con ▁countries ▁joined ▁the ▁project . ▁ ▁With ▁the ▁exception ▁of ▁only ▁a ▁few ▁hardware ▁pieces , ▁the ▁ES ▁machines ▁were ▁recognized ▁in ▁the ▁Western ▁countries ▁as ▁independently ▁designed , ▁based ▁on ▁legit imate ▁Soviet ▁pat ents . ▁Un like ▁the ▁hardware , ▁which ▁was ▁quite ▁original , ▁mostly ▁created ▁by ▁reverse - engine ering , ▁much ▁of ▁the ▁software ▁was ▁based ▁on ▁slightly ▁modified ▁and ▁local ized ▁IBM ▁code . ▁In ▁ 1 9 7 4 – 1 9 7 6 , ▁IBM ▁had ▁contact ed ▁the ▁Soviet ▁authorities ▁and ▁expressed ▁interest ▁in ▁ES ▁E VM ▁development ; ▁however , ▁after ▁the ▁Soviet ▁Army ▁entered ▁Afghan istan , ▁in ▁ 1 9 7 9 , ▁all ▁contacts ▁between ▁IBM ▁and ▁ES ▁developers ▁were ▁interrupted , ▁due ▁to ▁the ▁U . S . ▁embargo ▁on ▁techn ological ▁co operation ▁with ▁the ▁USS R . ▁ ▁Due ▁to ▁the ▁Co Com ' s ▁restrictions , ▁much ▁of ▁the ▁software ▁local ization ▁was ▁done ▁through ▁dis ass emb ling ▁the ▁IBM ▁software , ▁with ▁some ▁minimal ▁modification . ▁The ▁most ▁common ▁operating ▁system ▁was ▁О С ▁Е С ▁( OS ▁ES ), ▁a ▁modified ▁version ▁of ▁OS / 3 6 0 ; ▁the ▁later ▁versions ▁of ▁О С ▁Е С ▁were ▁very ▁original ▁and ▁different ▁from ▁the ▁IBM ▁OS es , ▁but ▁they ▁also ▁included ▁a ▁lot ▁of ▁original ▁IBM ▁code . ▁There ▁were ▁even ▁an ec dot al ▁rum ors ▁among ▁the ▁Soviet ▁program mers , ▁that ▁this ▁supposed ly ▁Soviet ▁operating ▁system