🚀 go-pugleaf

Good morning,

	I've just spent the better part of the night trying to figure out why
COM3 and COM4 exist if, (at least on the hardware I'm dealing with), they have
to share IRQ4 and IRQ3 with COM1 and COM2. 
	Basically, I'm trying to figure out if there is any way to get a 
serial mouse, a fax modem and a serial port for terminal emulation to all
work together. I'm working with a 386 which has jumpers to configure or disable
the built-in serial ports and a Laser (repackaged Cardinal) 9600 bps fax modem
which can be jumpered to any of the "standard" configurations for COM1-4.
	I figure I'm SOL on getting everything to work at once but was thinking
of using the mouse on COM1 and using IRQ3 to use the modem and serial port as
COM2 and COM4. What kind of problems am I asking for if I share the interrupt
but never use both ports at the same time? 
	I'm not a novice when it comes to interrupt juggling, but this is the
first time I've had to deal with COM3-4 stuff so any advice would be
appreciated.

Thanx in advance
Rob