To the OP. This is not unusual at all. Intel for many years and maybe still does used Digital Equipment's VMS OS and Vax CPU servers to run their fab plants.
In the mid 70's I was setting up a mainframe (DEC, digital equipment corp) in an anachoic chamber to be fcc tesed. The president of Toyota Japan was touring. Tons of suits in there (my machine was the first in this brand new room) and here I was, in my teeshirt setting up the mainframe (yes, the only one doing real work in that room). So the President of Toyota turns to me and asks me, "Why are you using a Hewlett Packard computer to test your computer? Why don't you use your own?" The answer was that HP designed test equipment in those days and they wrote the FCC testing software which could only run on one of their minicomputers. Anyone remember minicomputers?