Daniel Leonid Slotnick (1931–1985) was a mathematician and computer architect. Slotnick, in papers published with John Cocke in 1958, discussed the use of parallelism in numerical calculations for the first time. He later served as the chief architect of the ILLIAC IV supercomputer. He was the principal investigator on a DARPA contract in the early 1970s that produced the ILLIAC IV and the ARPANET. It was a fairly large operation, with its own building on the UIUC campus, originally called the Center for Advanced Computation but which is now the Astronomy Building. ILLIAC IV was constructed by Burroughs Corporation, using some special chips made by Fairchild Semiconductor. Because of campus unrest due to the Vietnam war, and the Mansfield amendments the ILLIAC IV was completed and installe