Device Input Modes

Return values from devices may be provided in:

Request Mode:

Alternating application and device execution

• application requests a return and then suspends execution;
• device wakes up, provides input and then suspends execution;
• application resumes execution.

Sample Mode:

Concurrent application and device execution

• device continually updates register(s) or memory location(s);
• application may read at any time.

Event Mode:

Concurrent application and device execution together with a concurrent queue management service

• device continually offers input to the queue
• application may request selections and services from the queue

  (or the queue may interrupt the application).