I/O Design
Two main concerns:
- Efficiency
- Most I/O devices are extremely slow compared to main memory
- Use of multiprogramming allows interleaving of I/O and processing
- Even in the future: I/O will not keep up with processor throughputs
- Swapping is used to bring in additional Ready processes; swapping is an I/O operation
- Generality
- Desirable to handle all I/O devices in a uniform manner
- Hide most of the details of device I/O in lower-level routines