Daniel Henry Holmes Ingalls Jr. (born 1944) is a pioneer of object-oriented computer programming and the principal architect, designer and implementer of five generations of Smalltalk environments. He designed the bytecoded virtual machine that made Smalltalk practical in 1976. He also invented bit blit, the general-purpose graphical operation that underlies most bitmap computer graphics systems today, and pop-up menus. He designed the generalizations of BitBlt to arbitrary color depth, with built-in scaling, rotation, and anti-aliasing. He made major contributions to the Squeak version of Smalltalk, including the original concept of a Smalltalk written in itself and made portable and efficient by a Smalltalk-to-C translator. Education Ingalls received his Bachelor of Arts (B.A.) in physics from Harvard University, and his Master of Science (M.S.) in electrical engineering from Stanford University. While working toward a Doctor of Philosophy (Ph.D.) at Stanford, he started a company to sell a software measurement invention that he perfected, and never returned to academia. Work Ingalls' first well known research was at Xerox PARC, where he began a lifelong research association with Alan Kay, and did his award-winning work on Smalltalk. As Peter Siebel wrote about Dan in his book Coders at Work, Reflections on the Craft of Programming, "If Alan Kay is Smalltalk’s father, Dan Ingalls is its mother—Smalltalk may have started as a gleam in Alan Kay’s eye, but Ingalls is the one who did the hard work of bringing it into the world. Starting with the first implementation of Smalltalk, written in BASIC and based on one page of notes from Kay, Ingalls has been involved in implementing seven generations of Smalltalk from the first prototype to the present-day open source implementation, Squeak." Dan's design principles for Smalltalk included the important concepts of personal mastery, good design in a uniform framework, language for communication, interaction of language, the concept of "objects", storage management, messages, and other principles outlined in his Byte Magazine article in 1981, "Design Principles of Smalltalk". In 2020, Ingalls wrote The Evolution of Smalltalk for the ACM HOPL Conference, ACM Program. Lang., Vol. 4, No. HOPL, Article 85. Publication date: June 2020, which details the design of Smalltalk through Ingalls's multiple iterations of the language, including his development of Squeak in 1996. Although some may not be familiar with the language of Smalltalk or the fact that it began object orientation in programming, it is still a useful and well-used language.