INT 16 U - PCIBM PC Tools v7 only CPSCHED/DESKTOP - ALTERNATE INSTALLATION CHECK
	AX = FEF1h
	BX = ???
Return: CX = 5555h if PCIBM PC Tools scheduler (CPSCHED or DESKTOP) installed
	DX = 5555h
Note:	this function is identical to AX=FFD3h, and is implemented by the same
	  code in DESKTOP
SeeAlso: AX=FFF1h