The first AS/400 systems (known by the development code names Silverlake, named for Silver Lake in downtown Rochester, Minnesota, where development of the system took place, and Olympic) were delivered in 1988 under the tag line "Best of Both Worlds" and the product line has been refreshed continually since then. The programmers who worked on OS/400, the operating system of the AS/400, did not have a UNIX background. Dr Frank Soltis, the chief architect, says that this is the main difference between this and any other operating system.