While a medical student, he developed software and carried out statistical computing, for researchers at MGH, and neuroelectric signal analysis for scientists studying the visual system in monkeys.
The LCS was directed by G. Octo Barnett, M.D., established under a subcontract to MGH from the Hospital Computer Project, a National Institutes of Health-supported grant to Bolt Beranek & Newman, Inc.[1] In 1966, for a research honors thesis for his M.D.
Further pursuing the interest in facilitating the human-computer interface, Greenes then worked with Neil Pappalardo and Curt Marble, two engineers in the LCS, along with Barnett, to develop a prototype of a minicomputer-based time-sharing system called MUMPS, for healthcare applications that included an interactive, interpretive programming language.
Shortly thereafter, he established the Decision Systems Group as a BMI research and development laboratory, which he directed for 27 years and which, at its peak, consisted of over 30 faculty, staff, and doctoral and postdoctoral fellows.
[2] From 1985 to 2007, Greenes directed the Harvard-based Biomedical Informatics Research Training (BIRT) program, with support from the National Library of Medicine and other sources.