Multiple choice general knowledge science & technology "Whistler" was the code name given for which Operating System? Windows Vista Windows XP Windows 98 Windows 95 Reveal answer Fill a bubble to check yourself B Correct answer Explanation Whistler was the internal codename for Windows XP during its development phase. Microsoft uses codenames like Longhorn (Vista), Blackcomb (cancelled), and Vienna (7) for products under development. Windows 98 was Memphis and Windows 95 was Chicago.