After a little research, here is a rough history of Object-Oriented Programming Languages for those of you that are interested (anyone? :-) )
'SketchPad' Program written by Ivan Edward Sutherland in 1961 - with some influence by Douglas T.Ross from the Lincoln Laboratory. Sketchpad was the first program to implement of 'class' and 'instance-based' inheritance (although not called classes and objects at the time) and abstraction through a graphical interface (the pre-cursor and influence on Xero-PARC and the Mac/Windows Graphical User Interface).
It's pretty amazing to think that in 1961 a program existed that enabled the user to create drawings on-screen with shape 'objects' and contraints that could be applied to your drawing. You could drag 'n' drop shapes and it even had the concept of a graphical 'button' which you could press to get it to execute your command. It used the pre-cursor to the mouse which was a light-pen. This was truly an amazing and ground-breaking program which has had a massive influence on OOP and OOD.
See the original live demo of Sketchpad (in two parts). You can see how Graphical User Interfaces evolved from Sketch. I like the way you can point the light pen directly on the screen - that's pretty cool and amazing for the time of course. For further technical details you might like to read the technical report submitted to Cambridge University.
Douglas T.Ross & C.A.R Hoare both sat on the Algol 68 Committee. Douglas T.Ross works on a record-like data structure (called a plex) which in turn influences C.A.R Hoare's ideas on abstract data types
Nygaard and Dahl cited C.A.R Hoare's idea on abstract data types as the origin of the class denition mechanisms in Simula [7]. Simula was the first Object-Oriented programming language, developed by the Norwegians at the Norwegian Computing Center. At a later stage Simula influenced the development of Smalltalk, a pure OOPL.
