Smalltalk

Software Concepts Group, Xerox PARC, led by Alan Kay, early 70's

Smalltalk took the concepts of class and message from SIMULA 67 and made them all-pervasive, the quintessential object-oriented language. Innovations included the graphical user interface: bitmap display, windowing system and use of mouse.

Smalltalk-72

Smalltalk-74

Smalltalk-76

Inheritance taken from SIMULA, and concurrency.

Smalltalk-78

"The Smalltalk-76 Programming System Design and Implementation", D. H. Ingalls, Conference Record of the 5th Annual ACM Symposium on Principles of Programming Languages, ACM 1978, pp.9-16.