Device Driver I/O and Interrupts

The essence of any computer system is to accept input data, process it, and produce output. How the system accepts input data is critical for real-time embedded systems. Because it needs to process the input data and output a response within a determined time interval. The most accurate way to achieve this would be to poll an input source constantly for data. This however puts a heavy burden on the CPU, limiting the system to just one task. Waiting for input data to arrive and react on it alleviates this burden and frees CPU resources. To be able to wait and react, we need hardware support for getting CPU attention away from its flow of processing.