More history ..
RML (as they were originally) made the 380z and 480z which were CP/M computers. The Nimbus (later Nimbus PC186) was similar to the IBM PC but not identical - at the time, there wasn't the complete standarisation which came later and it wasn't unreasonable to do things differently eg the 640kb limit wasn't there - the Nimbus could have 1Mb of RAM or 1.5Mb if you wanted a RAM disc.
The AX and VX machines and then the PC286 and PC386 machines they made in the late 80s were completely IBM compatible (former were AT bus; latter were MCA) but they could also emulate the graphics of the 186 machine - not much use for many people but much better than the IBM CGA.
Windows was available on RM kit from its earliest days and RM/RML were shipping networks long before many other companies.