I thought it came from a play on the naming convention. I don&#x27;t have the source but it went something like this:<p>System&#x2F;360 - The system for the 60&#x27;s<p>System&#x2F;370 - The system for the 70&#x27;s<p>System&#x2F;390 - The system for the 90&#x27;s<p>System&#x2F;Z - The system for the 2000&#x27;s, which sounds like a Z to some at the end.