That's actually pretty common in larger systems. You don't want your big, expensive machine bogged down with all the simple, stupid housekeeping stuff, so most

That's actually pretty common in larger systems. You don't want your big, expensive machine bogged down with all the simple, stupid housekeeping stuff, so most big iron machines have a frontend processor of some sort to handle that. The DECs used a PDP/11 or an Intel 8080, depending on model, IBM tended to use PCs or Thinkpads running special versions of OS/2, etc.