premise: Windows 98 (codenamed Memphis while in development) is a graphical operating system by Microsoft. It is the second major release in the Windows 9x line of operating systems and the successor to Windows 95. It was released to manufacturing on May 15, 1998 and to retail on June 25, 1998.
hypothesis: Windows 98 development was code named with a name that could be a city in Tennessee 
reason: Memphis is in Tennessee and the developmental code name is Memphis