INT 2F U - DOS 4.x only SHELLB.COM - SHELLC.EXE INTERFACE                       
	AX = 1901h
	BL = SHELLC type
	    00h transient
	    01h resident
	DS:DX -> far call entry point for resident SHELLC.EXE
Return: ES:DI -> SHELLC.EXE workspace within SHELLB.COM
Note:	SHELLB.COM and SHELLC.EXE are parts of the DOS 4.x shell