RM computers were predominantly sold to schools and colleges in the United Kingdom for use as LAN workstations in classrooms.
The operating system was started from a floppy disk or via a remote boot ROM on its network interface card, connecting to the LAN's fileserver.
The PC-286 and early PC-386 versions were termed the M Series due to the MCA bus used, and had a similar case design to that used by later models of the PC-186.
Later RM PCs using the 386 processor used an ISA bus and were shipped in a particularly ("S" for) slimline desktop case with only two 3.5" drive bays.
By this point, RM's computers were essentially ordinary IBM clones being sold specifically to the education market, with standard processors and buses, operating systems and software, as well as the normal ports (5-pin AT keyboard, 9-pin serial - including the mouse, 15-pin HD-sub VGA - although some 386 models used the less common 9-pin variant, etc), and the previous non-standard holdovers from the 380Z days long since abandoned.
Despite moving to a standard IBM-compatible architecture from the X series onwards, RM somewhat unusually maintained backwards compatibility with software written for their original Nimbus model by way of a "PC186" program that could be launched from MS-DOS or via a Windows icon, that would load a BIOS extension TSR and restart Windows in Real Mode.