Note: This API calls are shared between DOS and Win16 personality.

DOSSHELL is a stripped down version of 16-bit Windows. Some APIs shared and same. DOSSHELL uses older version of API, but Win16 has more advanced APIs.

INT 2FH, AH=4BH

SI	Description	Version
1	BUILD CALLOUT CHAIN	?
2	INSTALLATION CHECK	?
3	ALLOCATE SWITCHER ID	?
4	FREE SWITCHER ID	?
5	IDENTIFY INSTANCE DATA	?
80H	RESET INTERNAL VARIABLES	WSWAP.EXE

Note: This API implemented by DOSSWAP.EXE under DOS and by WINOLDAP.MOD under Windows