INT 17 - NorthNet Jetstream API - INSTALLATION CHECK

	AH = F0h
	DX = printer port (0-3)
Return: AX = 0001h Jetstream present
	     else  non-Jetstream port
Note:	NorthNet Jetstream is a high-performance DMA-driven parallel card able
	  to drive printers at up to 80000 characters per second