Chapter 3
A typical COM port on a motherboard or expansion card contains a UART
that interfaces to the system bus, typically a PCI bus. Each UART uses a series
of eight port addresses. The first address in the series is the port’s base address.
Most of these ports also have an assigned IRQ line to carry interrupt requests.Ports on motherboards or expansion cards have a Resources tab that displays the port
addresses and IRQ line the port uses. If you uncheck Use automatic settings, you may be
able to change the resources.