[1] Implementation of a TT system will typically involve use of a single interrupt that is linked to the periodic overflow of a timer.
This interrupt may drive a task scheduler (a restricted form of real-time operating system).
[1] Since publication of PTTES, extensive research work on TT systems has been carried out.
Implementation of an ET system will typically involve use of multiple interrupts, each associated with specific periodic events (such as timer overflows) or aperiodic events (such as the arrival of messages over a communication bus at random points in time).
ET designs are traditionally associated with the use of what is known as a real-time operating system (or RTOS), though use of such a software platform is not a defining characteristic of an ET architecture.