2 s ▁has ▁the ▁shared ▁address ▁space ▁and ▁co oper ative ▁mult it ask ing ▁characteristics ▁of ▁Windows ▁ 3 . 1 . ▁Con sequently , ▁for ▁a ▁Win 3 2 ▁application ▁to ▁run ▁on ▁Win 3 2 s , ▁it ▁must ▁contain ▁re location ▁information . ▁ ▁A ▁technique ▁named ▁th unk ing ▁is ▁fundamental ▁to ▁the ▁implementation ▁of ▁Win 3 2 s ▁as ▁well ▁as ▁Chicago - kernel ▁operating ▁systems , ▁which ▁are ▁Windows ▁ 9 5 , ▁Windows ▁ 9 8 , ▁and ▁Windows ▁ME . ▁However , ▁allowing ▁user - level ▁th unk ing ▁greatly ▁comp licates ▁attempts ▁to ▁provide ▁stable ▁memory ▁management ▁or ▁memory ▁protection ▁on ▁a ▁system - wide ▁basis , ▁as ▁well ▁as ▁core ▁or ▁kernel ▁security — this ▁allows ▁poor ly ▁written ▁applications ▁to ▁und erm ine ▁system ▁stability ▁on ▁Win 3 2 s , ▁as ▁well ▁as ▁the ▁Chicago - kernel ▁systems . ▁ ▁The ▁stability ▁and ▁security ▁Windows ▁N T ▁can ▁offer ▁is ▁partially ▁based ▁on ▁th unk ing ▁being ▁illegal , ▁except ▁th unks ▁from ▁Win 1 6 ▁to ▁Win 3 2 — the ▁CPU ▁must ▁remain ▁in ▁protected ▁mode ▁at ▁all ▁times . ▁ ▁Windows ▁XP ▁and ▁later ▁ 3 2 - bit ▁versions ▁of ▁Windows ▁trans par ently ▁provide ▁a ▁virtual ▁machine ▁for ▁running ▁Win 1 6 ▁applications , ▁although ▁this ▁feature ▁was ▁removed ▁from ▁ 6 4 - bit ▁versions ▁of ▁Windows . ▁ ▁Comp at ibility ▁ ▁Win 3 2 s - compatible ▁applications ▁could ▁be ▁built ▁using