INT 16 U - PCIBM PC Tools v7+ CPSCHED/DESKTOP - INSTALLATION CHECK
	AX = FEEFh
	CX = 0000h
Return: CX = ABCDh if PCIBM PC Tools scheduler (CPSCHED or DESKTOP) installed
	    BX = segment of resident portion
	    DX = (CPSCHED v8.0) resident CS
Note:	this function is identical to AX=FFD3h, and is implemented by the same
	  code in DESKTOP
SeeAlso: AX=FFEFh