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Fernando José "Corby" Corbató (born July 1, 1926) is a prominent American computer scientist, notable as a pioneer in the development of time-sharing operating systems.

Fernando José Corbató
Fernando Corbato.jpg
Born (1926-07-01) July 1, 1926 (age 92)
Alma materCalifornia Institute of Technology
Massachusetts Institute of Technology
Known forMultics
AwardsTuring Award (1990)
Computer History Museum Fellow (2012) [1]
Scientific career
FieldsComputer Scientist
InstitutionsMassachusetts Institute of Technology
ThesisA calculation of the energy bands of the graphite crystal by means of the tight-binding method (1956)
Doctoral advisorJohn C. Slater[2]
Doctoral studentsJerome H. Saltzer



Born in Oakland, California, Corbató received a bachelor's degree from the California Institute of Technology in 1950, and then a PhD in physics from the Massachusetts Institute of Technology in 1956. He joined MIT's Computation Center immediately upon graduation, became a professor in 1965, and stayed at MIT until he retired.

The first timesharing system he was associated with was known as the MIT Compatible Time-Sharing System (CTSS), an early version of which was demonstrated in 1961.[3] Corbató is credited with the first use of passwords to secure access to files on a large computer system, though he now says that this rudimentary security method has proliferated and become unmanageable.[4]

The experience with developing CTSS led to a second project, Multics, which was adopted by General Electric for its high-end computer systems (later acquired by Honeywell). Multics pioneered many concepts now used in modern operating systems, including a hierarchical file system, ring-oriented security, access control lists, single level store, dynamic linking, and extensive on-line reconfiguration for reliable service. Multics, while not particularly commercially successful in itself, directly inspired Ken Thompson to develop Unix, the direct descendants of which are still in extremely wide use; Unix also served as a direct model for many other subsequent operating system designs.


Among many awards, Corbató received the Turing Award in 1990, "for his pioneering work in organizing the concepts and leading the development of the general-purpose, large-scale, time-sharing and resource-sharing computer systems".

In 2012, he was made a Fellow of the Computer History Museum "for his pioneering work on timesharing and the Multics operating system".[5]


Corbató is sometimes known for "Corbató's Law" which states:[6]

The number of lines of code a programmer can write in a fixed period of time is the same, independent of the language used.

Corbató is recognized as helping to create the first computer password.[7]

Personal lifeEdit

Corbató has a wife, Emily. He has two daughters, Carolyn and Nancy Corbató (by his late wife Isabel), and two step-sons, David and Jason Gish.


See alsoEdit


  1. ^ Fernando Corbato 2012 Fellow Archived 2012-04-03 at the Wayback Machine
  2. ^ Fernando J. Corbató at the Mathematics Genealogy Project
  3. ^ Levy, Steven (2010). "Winners and Losers". Hackers: Heroes of the Computer Revolution - 25th Anniversary Edition (1st ed.). Sebastopol, CA: O'Reilly Media. pp. 85–102. ISBN 978-1449388393.
  4. ^ Warnock, Eleanor; Pfanner, Eric (May 22, 2014). "Despite Data Thefts, The Password Endures". Wall Street Journal.
  5. ^ "Fernando Corbato". Computer History Museum. Archived from the original on 2012-04-03. Retrieved 2013-05-23.
  6. ^ Originally from Corbató, F. J. (6 May 1969). "PL/I as a Tool for System Programming". Datamation. 15 (5): 68–76. Archived from the original on 6 February 2008. Regardless of whether one is dealing with assembly language or compiler language, the number of debugged lines of source code per day is about the same!
  7. ^ Yadron, Danny. "Man Behind the First Computer Password: It's Become a Nightmare". The Wall Street Journal. The Wall Street Journal. Retrieved 15 June 2015.

Further readingEdit

  • Dag Spicer, "Fernando Corbató: Time-Sharing Pioneer, Part 1", IEEE Annals of the History of Computing, vol.37, no. 4, pp. 5-9, Oct.-Dec. 2015, doi:10.1109/MAHC.2015.81
  • Dag Spicer, "Fernando Corbató: Time-Sharing Pioneer, Part 2", IEEE Annals of the History of Computing, vol.38, no. 1, pp. 75-79, Jan.-Mar. 2016, doi:10.1109/MAHC.2016.7

External linksEdit