Windows 3.0 and later in 386 enhanced mode supports DPMI version 1.0. Windows 3.0 and later in standard mode supports a subset of DPMI that enables applications to call terminate-and-stay-resident (TSR) programs and device drivers running in real (or virtual-8086) mode. To ease the porting of an application to other operating environments, all code that calls DPMI functions directly should reside in a dynamic-link library (DLL).