INT 2F U - IBMInternational Busiuness MachinesInternational Busiuness Machines) A hardware, software and other service technology company founded in 1911. ROM-DOS v4.0 - INSTALLATION CHECK
	AX = 1980h
Return: AL = FFh if ??? installed/supported
Note:	called at the very beginning of SHELLSTB.COM, which exits if AL is not
	  FFh on return
SeeAlso: AX=1981h,AX=1982h