DOS Extender functions

 DosAllocHuge()                Allocate extended memory block of up to 16MB.
 DosAllocRealSeg()             Allocate conventional memory block.
 DosAllocSeg()                 Allocate extended memory block of up to 64 Kb.
 DosCreateCSAlias()            Create executable (code) selector corresponding to data selector.
 DosCreateDSAlias()            Create data selector corresponding to executable (code) selector.
 DosFreeRealSeg()              Free selector previously allocated with DosAllocRealSeg()
 DosFreeSeg()                  Free memory block allocated with DosAllocSeg() or DosAllocHuge().
 DosFreeSelector()             Free selector allocated with DosMapRealSeg(), DosCreateCSAlias() or DosCreateDSAlias()
 DosGetBIOSSeg()               Get selector for 1kb BIOS data area.
 DosGetExceptionHandler()      Get protected mode address of exception handler
 DosGetHostMode()              Get current DOS extender host mode (DPMI, VCPI, XMS).
 DosGetHugeShift()             Get left shift count to apply to 1 to get huge selector increment value.
 DosGetMachineMode()           Get current machine mode (real, 286 protected).
 DosGetProtVec()               Get protected mode pointer to protected mode interrupt handler
 DosGetRealVec()               Get real mode pointer to real mode interrupt handler
 DosGetSegBase()               Get base address of segment selector.
 DosGetSegDesc()               Get descriptor structure of segment selector.
 DosGetSegLimit()              Get size limit of segment selector.
 DosIsBlinkX()                 Determine whether program is running under Blinker DOS extender.
 DosLockSeg()                  Lock segment in memory to prevent it being swapped out by Blinker DOS extender's VM system.
 DosMapRealSeg()               Convert real mode paragraph value into protected mode selector.
 DosMemAvail()                 Get total available extended memory.
 DosRealAvail()                Get total available real mode memory.
 DosRealFarCall()              Make far call to real mode address
 DosRealIntr()                 Generate real mode interrupt from protected mode.
 DosReallocHuge()              Resize extended memory block of up to 16 MB.
 DosReallocSeg()               Resize extended memory block of up to 64kb.
 DosSetExceptionHandler()      Install protected mode exception handler
 DosSetProtVec()               Install protected mode interrupt handler
 DosSetRealVec()               Install real mode interrupt handler
 DosSetSegAttrib()             Set segment attributes for selector
 DosUnlockSeg()                Unlock segment previously locked using DosLockSeg()
 DosVerifyAccess()             Get read/write/code/data flags for selector
 DosVMAvail()                  Get amount of available virtual memory