COM3 shared the interrupt of COM1 (IRQ4), and COM4 shared the interrupt of COM2 (IRQ3). Because of the limited number of IRQ addresses available, any additional COM ports would have to share IRQs with existing ports. While those two IRQs are still the standard for COM ports 1 and 2, many BIOS routines will allow different IRQ assignments or even allow an unused port to be disabled. The original 8088-based IBM PCs were equipped with two serial ports: COMl, set to IRQ4, and COM2, set to IRQ3. The network card is probably the best choice, because the modem is installed and already working. You will have to change the IRQ on one of the devices. You realize the network card and the modem will conflict, and the computer will lock up. You buy a network card that comes out of the box with a default setting of IRQ 4. Installation Problems with COM PortsĪssume you have a modem set to COMl. Simply assign the device to the now-free port. By disabling one of these ports, you have made its address and IRQ available for use by the internal device. If necessary, these ports can be disabled (by using CMOS setup), freeing their I/O addresses and IRQs for another device.įor example, suppose you want to install a new internal modem on a machine that has two external serial ports on the motherboard. This makes it possible to install an external device simply by plugging in the port and assigning addresses to the device. In this case, the standard port addresses and IRQs are assigned to them. Most computers are manufactured to offer built-in physical ports with cable connections available either directly to the motherboard or in an expansion slot. The following table lists standard ports. When assigned to an active port (as long as no other device is using that port), they will work. Modems and printers, therefore, do not require IRQ or I/O settings. All Brainboxes XC cards are PCI Express Base Specification 1.1 Compliant.The purpose of a port is to make installation easier. Unlike the VX range which uses USB technology over ExpressCard, this uses PCI Express technology over ExpressCard. Microsoft Windows 7 32 bit & 64 bit EditionsĮxpressCard PCIe Implementation.Microsoft Windows 8 32 bit & 64 bit Editions.Industrial Embedded Ethernet Switch Moduleģ4mm (fits both 34mm and 54mm ExpressCard slots).

Printer ports lpt