▁API ▁as ▁it ▁existed ▁in ▁early ▁versions ▁of ▁Windows ▁N T . ▁ ▁The ▁" s " ▁in ▁Win 3 2 s ▁sign ifies ▁subset , ▁as ▁Win 3 2 s ▁lack ed ▁a ▁number ▁of ▁Windows ▁N T ▁functions , ▁including ▁multi - thread ing , ▁asynchronous ▁I / O , ▁newer ▁serial ▁port ▁functions ▁and ▁many ▁G DI ▁extensions . ▁This ▁generally ▁limited ▁it ▁to ▁" Win 3 2 s ▁applications " ▁which ▁were ▁specifically ▁designed ▁for ▁the ▁Win 3 2 s ▁platform , ▁although ▁some ▁standard ▁Win 3 2 ▁programs ▁would ▁work ▁correctly , ▁including ▁Microsoft ' s ▁ 3 D ▁Pin ball ▁Space ▁Cad et , ▁Windows ▁ 9 5 ' s ▁included ▁app lets , ▁and ▁Office ▁ 9 5 . ▁Early ▁versions ▁of ▁Internet ▁Explorer ▁( up ▁to ▁Version ▁ 5 ) ▁were ▁also ▁Win 3 2 s ▁compatible , ▁although ▁these ▁also ▁existed ▁in ▁ 1 6 - bit ▁format . ▁Gener ally , ▁for ▁a ▁ 3 2 - bit ▁application ▁to ▁be ▁compatible ▁with ▁Win 3 2 s , ▁it ▁had ▁to ▁not ▁use ▁more ▁than ▁ 1 6 MB ▁of ▁memory ▁or ▁any ▁extended ▁features ▁such ▁as ▁Direct X . ▁ ▁Win 3 2 s ▁inher its ▁many ▁of ▁the ▁limitations ▁of ▁the ▁Win 1 6 ▁environment . ▁True ▁Win 3 2 ▁applications ▁execute ▁within ▁a ▁private ▁virtual ▁address ▁space , ▁whereas ▁Windows ▁ 3 . x ▁used ▁an ▁address ▁space ▁shared ▁among ▁all ▁running ▁applications . ▁An ▁application ▁running ▁on ▁Win 3