What is the difference between interrupt-driven I/O versus polling I/O?
Most input and output devices are much slower than the CPU—so much slower that it would be a terrible waste of the CPU to make it wait for the input devices. For example, compare the speed you can type with the speed the CPU can execute instructions. Even a very fast typist could probably type no more than 10 characters per second, while a modern CPU can execute more than two billion instructions in that same second!