IO Design Objectives
Efficiency : IO operations often form the bottleneck in a computing system.
Generality: Handle all devices in a uniform manner. How?
- Use hierarchical, modular approach to design of IO subsystem.
- This approach hides most of the details of device details in lower-levels so that processes and upper levels of OS see devices in terms of general functions such as Read, Write, Open, Lock, UnLock etc.