The non-retentive timer's DN bit is set when its accumulated value equals what?

The non-retentive timer is designed to measure time intervals but does not retain its accumulated value after the timer has expired or been reset. In a non-retentive timer, the Done (DN) bit is an indicator that signifies when the timer has completed its timing cycle.

In this context, the DN bit is specifically set when the accumulated time reaches the pre-set value defined for the timer. The pre-set value represents the target duration that the timer is meant to count up to, and once this duration is achieved, it triggers the Done bit to indicate that the timer has finished counting.

Hence, the occurrence of the DN bit being set enables the system to take subsequent actions, based on the completion of the time cycle specified by the pre-set value. This characteristic is fundamental for effectively using non-retentive timers in control systems, allowing for precise timing and control functions as dictated by the application's requirements.