Interrupt controlled system

Some embedded systems are predominantly interrupt controlled. This
means that tasks performed by the system are triggered by different
kinds of events. An interrupt could be generated for example by a
timer in a predefined frequency, or by a serial port controller
receiving a byte.

These kinds of systems are used if event handlers need low latency and
the event handlers are short and simple.

Usually these kinds of systems run a simple task in a main loop also,
but this task is not very sensitive to unexpected delays.

Sometimes the interrupt handler will add longer tasks to a queue
structure. Later, after the interrupt handler has finished, these
tasks are executed by the main loop. This method brings the system
close to a multitasking kernel with discrete processes.