Stephen Curtis Johnson (born 1944) is a

computer scientist A computer scientist is a scientist who specializes in the academic study of computer science. Computer scientists typically work on the theoretical side of computation. Although computer scientists can also focus their work and research on ...

who worked at

Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...

and

AT&T AT&T Inc., an abbreviation for its predecessor's former name, the American Telephone and Telegraph Company, is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the w ...

for nearly 20 years. He is best known for

Yacc Yacc (Yet Another Compiler-Compiler) is a computer program for the Unix operating system developed by Stephen C. Johnson. It is a lookahead left-to-right rightmost derivation (LALR) parser generator, generating a LALR parser (the part of a co ...

, Lint, spell, and the

Portable C Compiler The Portable C Compiler (also known as pcc or sometimes pccm - portable C compiler machine) is an early compiler for the C programming language written by Stephen C. Johnson of Bell Labs in the mid-1970s, based in part on ideas proposed by Alan ...

, which contributed to the spread of

Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

and C. He has also contributed to fields as diverse as computer music,

psychometrics Psychometrics is a field of study within psychology concerned with the theory and technique of measurement. Psychometrics generally covers specialized fields within psychology and education devoted to testing, measurement, assessment, and rela ...

and VLSI design.

Life and education

Johnson's passion for computing started at age five, when his grandfather took him along to his work at the Bureau of Standards. The computer he saw ("the size of a small house") made a strong impression on him, and he decided he "wanted to work with computers, and never looked back after". There were no computer science classes in college, so he studied mathematics, in which he eventually earned a PhD.

Career

Bell Labs and AT&T

Johnson joined

and

in the 1960s and worked on

tools for nearly 20 years, alongside computer scientists like

Jeffrey Ullman Jeffrey David Ullman (born November 22, 1942) is an American computer scientist and the Stanford W. Ascherman Professor of Engineering, Emeritus, at Stanford University. His textbooks on compilers (various editions are popularly known as the dr ...

Dennis Ritchie Dennis MacAlistair Ritchie (September 9, 1941 – October 12, 2011) was an American computer scientist. He created the C programming language and the Unix operating system and B language with long-time colleague Ken Thompson. Ritchie and Thomp ...

and

Alfred Aho Alfred Vaino Aho (born August 9, 1941) is a Canadian computer scientist best known for his work on programming languages, compilers, and related algorithms, and his textbooks on the art and science of computer programming. Aho was elected into ...

. He was best known for writing

, Lint, and the

. In the mid-1970s, Johnson and Bell colleague

co-authored the first AT&T

port. They also "demonstrated that Unix was

portable Portable may refer to: General * Portable building, a manufactured structure that is built off site and moved in upon completion of site and utility work * Portable classroom, a temporary building installed on the grounds of a school to provide a ...

", which Ritchie considers the spark that led to Unix becoming widespread. In the mid-1980s, he served as the head of the UNIX Languages Department (

UNIX System V Unix System V (pronounced: "System Five") is one of the first commercial versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, numbered 1, 2, 3, an ...

). Johnson developed

in the early '70s because he wanted to insert an

exclusive or Exclusive or, exclusive disjunction, exclusive alternation, logical non-equivalence, or logical inequality is a logical operator whose negation is the logical biconditional. With two inputs, XOR is true if and only if the inputs differ (on ...

operator into Ritchie's B language compiler. Bell Labs colleague

suggested he look at

Donald Knuth Donald Ervin Knuth ( ; born January 10, 1938) is an American computer scientist and mathematician. He is a professor emeritus at Stanford University. He is the 1974 recipient of the ACM Turing Award, informally considered the Nobel Prize of comp ...

's work on LR parsing, which served as the basis for Yacc. In a 2008 interview, Johnson reflected that "the contribution Yacc made to the spread of

and C is what I'm proudest of". Lint was developed in 1978 while Johnson was debugging the Yacc grammar he was writing for C and struggling with portability issues stemming from porting

to a

32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in a maximum of 32- bit units. Compared to smaller bit widths, 32-bit computers can perform la ...

machine.

Silicon Valley

In 1986, Johnson moved to

Silicon Valley Silicon Valley is a region in Northern California that is a global center for high technology and innovation. Located in the southern part of the San Francisco Bay Area, it corresponds roughly to the geographical area of the Santa Clara Valley ...

, where he joined several

startups A startup or start-up is a company or project undertaken by an Entrepreneurship, entrepreneur to seek, develop, and validate a scalable business model. While entrepreneurship includes all new businesses including self-employment and businesses tha ...

, where he worked mostly on

compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...

s, but also 2D and 3D graphics,

massively parallel Massively parallel is the term for using a large number of computer processors (or separate computers) to simultaneously perform a set of coordinated computations in parallel. GPUs are massively parallel architecture with tens of thousands of ...

computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and softw ...

and

embedded system An embedded system is a specialized computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is e ...

s. The startups included Dana Computer, Inc., Melismatic Software, and

Transmeta Transmeta Corporation was an American fabless semiconductor company based in Santa Clara, California. It developed low power x86 compatible microprocessors based on a VLIW core and a software layer called Code Morphing Software. Code Morphing ...

, which made low-power,

Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer compo ...

-compatible

microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...

s. Johnson served on the

USENIX USENIX is an American 501(c)(3) nonprofit membership organization based in Berkeley, California and founded in 1975 that supports advanced computing systems, operating system (OS), and computer networking research. It organizes several confe ...

board for ten years, including four years as president in the early 1990s. He now serves as the USENIX representative to the Computing Research Association.

Later career

In 2002, he moved to Boston to work at

MathWorks The MathWorks, Inc. is an American privately held corporation that specializes in mathematical computing software. Its major products include MATLAB and Simulink, which support data analysis and simulation. History MATLAB was created in the 1 ...

, where he helped maintain the front end of the

MATLAB MATLAB (an abbreviation of "MATrix LABoratory") is a proprietary multi-paradigm programming language and numeric computing environment developed by MathWorks. MATLAB allows matrix manipulations, plotting of functions and data, implementat ...

programming language, for which he also built a lint product called M-Lint. He had met MathWorks founder

Cleve Moler Cleve Barry Moler (born August 17, 1939) is an American mathematician and computer programmer specializing in numerical analysis. In the mid to late 1970s, he was one of the authors of LINPACK and EISPACK, Fortran libraries for numerical compu ...

while working at a Silicon Valley startup and developed a "long-distance consulting relationship" with him in the 1990s. As of 2018 Johnson currently lived in Morgan Hill, California busy working on energy-efficient computers for

machine learning Machine learning (ML) is a field of study in artificial intelligence concerned with the development and study of Computational statistics, statistical algorithms that can learn from data and generalise to unseen data, and thus perform Task ( ...

at Wave Computing.

References

{{DEFAULTSORT:Johnson, Stephen C Unix people Scientists at Bell Labs Living people 1944 births