INT 10 - UNCHAIN - INSTALLATION CHECK                                           
	AX = CBFFh
Return: AX = CCBBh if installed
Program: UNCHAIN is a TSR(Terminate and Stay Resident) A program which remains in memory after terminating in order to provide services to other programs or the user.  The name comes from the name of the DOS function call used to remain in memory after termination. by Colin Buckley which permits use of Borland
	  development tools with Mode X video in the absence of a second
	  monitor
SeeAlso: AX=CB00h,AX=CB01h,AX=CB06h