Fernando J. Corbató

Fernando José "Corby" Corbató (July 1, 1926 – July 12, 2019) was a prominent American computer scientist, notable as a pioneer in the development of time-sharing operating systems.

Fernando J. Corbató
Fernando José Corbató

(1926-07-01)July 1, 1926
DiedJuly 12, 2019(2019-07-12) (aged 93)
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


Corbató was born on July 1, 1926 in Oakland, California, to Hermenegildo Corbató, a Spanish literature professor from Villarreal, Spain, and Charlotte (née Carella Jensen) Corbató. In 1930 the Corbató family moved to Los Angeles for Hermenegildo's job at UCLA.

In 1943, Corbató enrolled at UCLA, but due to World War II he was recruited by the Navy during his first year. During the war, Corbató "debug[ged] an incredible array of equipment", inspiring his future career.[3]

Corbató left the Navy in 1946, enrolled at the California Institute of Technology, and received a bachelor's degree in physics in 1950. He then earned 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.[3]

The first time-sharing system he was associated with was known as the MIT Compatible Time-Sharing System (CTSS), an early version of which was demonstrated in 1961.[4] 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.[5]

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".[6]


Corbató is sometimes known for "Corbató's Law" which states:[7]

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.[8]

Personal life and death

Corbató married programmer Isabel Blandford in 1962; she died in 1973.[3]

Corbató had a second wife, Emily (née Gluck); two daughters, Carolyn Corbató Stone and Nancy Corbató, by his late wife Isabel; two step-sons, David Gish and Jason Gish; a brother, Charles; and five grandchildren.[3]

Corbató died on July 12, 2019 in Newburyport, Massachusetts, at the age of 93 due to complications from diabetes.[3]


See also


  1. Fernando Corbato 2012 Fellow Archived 2012-04-03 at the Wayback Machine
  2. Fernando J. Corbató at the Mathematics Genealogy Project
  3. Hafner, Katie (July 12, 2019). "Fernando Corbató, a Father of Your Computer (and Your Password), Dies at 93". The New York Times. Retrieved 13 July 2019.
  4. 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.
  5. Warnock, Eleanor; Pfanner, Eric (May 22, 2014). "Despite Data Thefts, The Password Endures". Wall Street Journal.
  6. "Fernando Corbato". Computer History Museum. Archived from the original on 2012-04-03. Retrieved 2013-05-23.
  7. 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!
  8. 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 reading

  • 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

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