Windows NT uses a very simple scheduling algorithm, which is to run the highest priority thread that is ready.
Windows NT maintains a dispatch queue, a list of ready processes. The queue is ordered by process priority. An interval timer periodically interupts processing, passing control to the thread scheduler, which dispatches the highest priority entry from the dispatch queue.
I have seen some documentation about a quota, which limits the amount of processor time that a thread can use, but this
is NOT implemented in Windows NT.