21. I/O Manager# 21.1. Introduction 21.2. Background 21.2.1. Device Driver Table 21.2.2. Major and Minor Device Numbers 21.2.3. Device Names 21.2.4. Device Driver Environment 21.2.5. Runtime Driver Registration 21.2.6. Device Driver Interface 21.2.7. Device Driver Initialization 21.3. Operations 21.3.1. Register and Lookup Name 21.3.2. Accessing an Device Driver 21.4. Directives 21.4.1. rtems_io_register_driver() 21.4.2. rtems_io_unregister_driver() 21.4.3. rtems_io_initialize() 21.4.4. rtems_io_register_name() 21.4.5. rtems_io_open() 21.4.6. rtems_io_close() 21.4.7. rtems_io_read() 21.4.8. rtems_io_write() 21.4.9. rtems_io_control()