May I please see a citation for your assertion that ASMP and SMP are terms of art rather than terms that have something to do with symmetry  If a system where all processors are equivalent in hardware and where the operating system doesnt assign special roles to any of the processors I fail to see any lack of symmetry between the processors so its not asymmetric in the dictionary sense  As for a progression that implies a onedimensional scale  Whether a system that has something that could be considered processes supports multiple processes per user session or supports multiple preemptivelyscheduled threads of control per process is orthogonal to the form of multiprocessing  A uniprocessor system or a multiprocessor system with only one processor running kernel code or a system where any processor can run kernel code but theres a giant lock around the kernel can support multiple processes per user session and many have and can even usefully support multiple preemptrivelyscheduled threads of control per process  The fact that Multics didnt support multiple processes per user session or multiple preemptivelyscheduled threads of control per process has nothing to do with whether it can make full use of multiple processors it was a multiuser system and multiple processes could be making ring  calls at the same time  The reference states  Multics system programmers working on the supervisor on the other hand worked in an environment in which many kinds of data were shared and had to be protected by locking and access conventions Ring  of a Multics process contained multiple shared databases that needed protection These protections and access conventions were created as a layer of usage convention on top of the execution environment provided by the hardware and PLI language  which at least suggests that Multics had something finergrained than a giant lock around ring  and indicates that there was no designated ring  CPU