Daniel Henry Holmes Ingalls, Jr. is a former researcher of Xerox PARC, and a pioneer of object-oriented computer programming. He was the main architect, designer, and implementor of five generations of Smalltalk environments, including the first. He designed the byte-coded virtual machine that made Smalltalk practical in 1976, a variant of which is central to Java today. His major contributions to Squeak Smalltalk are the original concept of a Smalltalk written in itself and made portable and efficient by a Smalltalk-to-C translator. He also invented Bit blit (BitBlt), the general-purpose graphic operation that underlies most bitmap graphics systems today, and designed generalizations of it to arbitrary color depth, with built-in scaling, rotation, and anti-aliasing. He invented pop-up menus.