A faster way would be for the device itself to put the data directly into main memory. One way to do this is by using DMA Channels or bus mastering. Another way is to allocate some space in main memory to the device. This way the device reads and writes directly to main memory without having to bother with DMA or bus mastering. Such a device may also use IO addresses.
Interrupts convey a lot of information but only indirectly.
These registers contain status information about the device . When such an interrupt is issued, the CPU runs all interrupt service routines for all devices using that interrupt. The first thing the first service routine does is to check to see if an interrupt actually happened for its device. 8.3 PCI Interrupts PCI interrupts are different but since they are normally mapped to IRQ's they behave in about the same way. A major difference is that PCI interrupts may be shared.