INT 49 - MAGic v1.16+ - GET SIZE OF FULL SCREEN

	AX = 0006h
Return: AX = status
	    0000h successful
		BX = vertical size (char rows or pixel rows)
		DX = horizontal size (char cols or 8-pixel units)
	    FFFFh MAGic busy, retry later
		BX,DX destroyed
	CX destroyed
SeeAlso: AX=0001h,AX=0005h,AX=0007h