Comm ports?

[Jetboy55]

I dont understand the use of the term com ports? Its like a comm port is just a logical thing like a logical drive in an extended partition. Am I correct in understanding that comm 1 is not necessarily a specific hardware connection? Like if my secondary serial port was called comm 2, and I disabled it, then comm 2 might become the port my modem is on? If so, I dont understand, modem is in a pci slot, not a com slot? Or am I right in thinking of a "comm port" as a set of resources designed and designated for communication devices, and assigned as needed to communication devices? Like a profile, eg..this irq and this memory address is "comm 2", but could be given to any one of the numerous communications devices (one at a time) I may have at a given time? I seem to remember once I ended up with a modem installed twice, USR Modem1 on comm 1, and USR Modem2 on comm 2, even though I only had one physical modem installed? Please explain what comm ports are and how they work. Thanks a million. This has confused me for a long time.

 

[John]

COM port is short for communications port. COM ports are also called serial ports and on PCs are sometimes called asynchronous communications ports. PCs can normally have up to 4 COM ports. Most PCs have 2 COM ports either built in to the motherboard or on an add-in I/O card. COM ports built in to a motherboard are usually configured with options in CMOS setup but may be configured with jumpers on the motherboard. COM ports on add-in cards are normally configured with jumpers on the card.


COM ports are configured to use a particular I/O port address and a particular IRQ (Interrupt Request Line). All COM ports in a system must be configured so that their I/O addresses and IRQs do not conflict. However some systems will allow two COM ports at different addresses to share the same IRQ while other systems will not allow sharing of IRQs.