Your history is pretty confused, although it has some elements of truth to it.  Let me set you straight.<p>Although there were graphical displays in the 1950s (some of them being simply direct displays of the contents of Williams tubes), GUIs as such only go back to Sketchpad (1961-65, roughly) which sort of had windows, and there were windows and a mouse in NLS by 1968, but without a GUI.  Simula (1967) wasn&#x27;t OO; Alan coined that phrase to describe Smalltalk (1971 at PARC, established 1970, which you&#x27;ll note is less than a decade after 1967, though begun in 1969), which drew inspiration from Sketchpad, Simula, the B5000, NLS, and some weird magnetic tape format developed by the Air Force where the tape started with a program that interpreted the rest of the tape, among other places.<p>Alan and Ed Cheadle actually did a lot of the development of the ideas that later became OO in the 1966-70 timeframe on a personal computer they were working on called FLEX.<p>You can read Alan&#x27;s account of this history in &quot;The Early History of Smalltalk&quot;, one copy of which is at <a href="http:&#x2F;&#x2F;gagne.homedns.org&#x2F;~tgagne&#x2F;contrib&#x2F;EarlyHistoryST.html" rel="nofollow">http:&#x2F;&#x2F;gagne.homedns.org&#x2F;~tgagne&#x2F;contrib&#x2F;EarlyHistoryST.html</a>.<p>Alan and Dan and Adele and other people on the Smalltalk team deserve a lot of credit both for developing the ideas of object-orientation but also for popularizing them, and essentially the modern desktop GUI (mouse, overlapping windows, icons, WYSIWYG, multiple fonts, proportional fonts, buttons, menus, drag-and-drop) was developed at PARC in the 1970s, an effort that included the Smalltalk team but also included a lot of other people working in other languages.<p>Of course, much as I detest Steve Jobs, the really powerful popularizing influences on this stuff were Macintosh and NeXT.  (Later, Java.)