Abstract: A computer system having a PCI expansion connector and further including: an operating system operable to detect a PCI-to-PCMCIA bridge on the PCI expansion connector and in response thereto to allocate a legacy interrupt channel for interrupts originating from the PCI-to-PCMCIA bridge, and also operable to detect connection of a PCMCIA card to the PCI-to-PCMCIA bridge and in response thereto to allocate a further legacy interrupt channel for interrupts originating from the PCMCIA card; and a device driver for a PCI-to-PCMCIA bridge, the device driver including a trap mechanism operable to intercept PCI interrupts received through the PCI expansion connector and, in response to interception of a PCI interrupt, to call an interrupt management routine operable to determine that one of said legacy interrupt channel and said further legacy interrupt channel associated with the intercepted PCI interrupt and to call an interrupt service routine using the determined legacy interrupt channel as an operand.