Many aspects of THE and Nucleus are still seen in modern operating systems. We
can start by mentioning memory management. THE illustrates what could be
considered as a primitive form of virtual memory. Concepts such as pages and
segments are introduced along with the description of a paging system.

THE also describes what seems a form of preemptive scheduling. The author
finds that the time succession of the various states of a sequential process
has a logical meaning, but not the actual speed in which the process is
performed. This allows for the interleaved execution of sequential
processes. Sequential processes cooperate by means of explicit mutual
synchronization statements. The idea of using interrupts is also introduced in
THE. Clock interrupts are used to avoid processing monopolization.

Another aspect seen in THE is the use of synchronization mechanisms such as
semaphores, which are used to enforce mutual exclusion. Semaphores, mutual
exclusion and critical sections are all concepts widely used in modern
operating systems. THE also describes deadlock, referring to it as the
circular wait or deadly embrace problem.

Nucleus introduces a form of inter-process communication by using message
buffering (they claimed that THE's semaphores were not sufficient). Nucleus
also presents the idea of creating processes from other processes (forking a
process). Finally, the idea of dividing the application space into internal
processes (user programs running in user space) and external processes
(handled by the Nucleus and running outside the user space) is still adopted
in modern operating systems (user programs vs device drivers).