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Stephen C. Johnson
Stephen Curtis Johnson (born 1944) is a computer scientist who worked at Bell Labs and AT&T for nearly 20 years. He is best known for Yacc, Lint, spell, and the Portable C Compiler, which contributed to the spread of Unix and C. He has also contributed to fields as diverse as computer music, psychometrics 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 Bell Labs and AT&T in the 1960s and worked on Unix tools for nearly 20 years, alongside computer scientists like Jeffrey Ullman, Dennis Ritchie and Alfred Aho. He was best known for writing Yacc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, applied disciplines (including the design and implementation of Computer architecture, hardware and Software engineering, software). Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and preventing security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 dragon book), theory of computation (also known as the Cinderella book), data structures, and databases are regarded as standards in their fields. He and his long-time collaborator Alfred Aho are the recipients of the 2020 Turing Award, generally recognized as the highest distinction in computer science.ACM Turing Award Honors Innovators Who Shaped the Foundations of Programming Language Compilers and Algorithms Retrieved March 31, 2021. Career Ullman received a Bachelor of S ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 threads. One approach is grid computing, where the processing power of many computers in distributed, diverse administrative domains is opportunistically used whenever a computer is available.''Grid computing: experiment management, tool integration, and scientific workflows'' by Radu Prodan, Thomas Fahringer 2007 pages 1–4 An example is BOINC, a volunteer-based, opportunistic grid system, whereby the grid provides power only on a best effort basis.''Parallel and Distributed Computational Intelligence'' by Francisco Fernández de Vega 2010 pages 65–68 Another approach is grouping many processors in close proximity to each other, as in a computer cluster. In such a centralized system the speed and flexibility of the interconnect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 primarily used for programs that translate source code from a high-level programming language to a lower level language, low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program.Compilers: Principles, Techniques, and Tools by Alfred V. Aho, Ravi Sethi, Jeffrey D. Ullman - Second Edition, 2007 There are many different types of compilers which produce output in different useful forms. A ''cross-compiler'' produces code for a different Central processing unit, CPU or operating system than the one on which the cross-compiler itself runs. A ''bootstrap compiler'' is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language. Related software ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Startup Company
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 that do not intend to Initial public offering, go public, startups are new businesses that intend to grow large beyond the solo-founder. During the beginning, startups face high uncertainty and have high rates of failure, but a minority of them do go on to become successful and influential, such as unicorn (finance), unicorns.Erin Griffith (2014)Why startups fail, according to their founders, Fortune.com, 25 September 2014; accessed 27 October 2017 Actions Startups typically begin by a founder (solo-founder) or co-founders who have a way to solve a problem. The founder of a startup will do the market validation by problem interview, solution interview, and building a minimum viable product (MVP), i.e. a prototype, to develop and validate thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. The term "Silicon Valley" refers to the area in which high-tech business has proliferated in Northern California, and it also serves as a general metonymy, metonym for California's high-tech business sector. The cities of Sunnyvale, California, Sunnyvale, Mountain View, California, Mountain View, Palo Alto, California, Palo Alto and Menlo Park, California, Menlo Park are frequently cited as the birthplace of Silicon Valley. Other major Silicon Valley cities are San Jose, California, San Jose, Santa Clara, California, Santa Clara, Redwood City, California, Redwood City and Cupertino, California, Cupertino. The San Jose Metropolitan Area has the third-highest GDP per capita in the world (after Zürich, Switzerland, and Oslo, Norway), accor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 large calculations more efficiently and process more data per clock cycle. Typical 32-bit personal computers also have a 32-bit address bus, permitting up to 4 GiB of RAM to be accessed, far more than previous generations of system architecture allowed. 32-bit designs have been used since the earliest days of electronic computing, in experimental systems and then in large mainframe and minicomputer systems. The first hybrid 16/32-bit microprocessor, the Motorola 68000, was introduced in the late 1970s and used in systems such as the original Apple Macintosh. Fully 32-bit microprocessors such as the HP FOCUS, Motorola 68020 and Intel 80386 were launched in the early to mid 1980s and became dominant by the early 1990s. This gener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LR Parser
In computer science, LR parsers are a type of bottom-up parsing, bottom-up parser that analyse deterministic context-free languages in linear time. There are several variants of LR parsers: SLR parsers, LALR parsers, canonical LR parser, canonical LR(1) parsers, canonical LR parser, minimal LR(1) parsers, and generalized LR parsers (GLR parsers). LR parsers can be generated by a parser generator from a formal grammar defining the syntax of the language to be parsed. They are widely used for the processing of computer languages. An LR parser (left-to-right, rightmost derivation in reverse) reads input text from left to right without backing up (this is true for most parsers), and produces a rightmost derivation in reverse: it does a bottom-up parsing, bottom-up parse – not a top-down parsing, top-down LL parse or ad-hoc parse. The name "LR" is often followed by a numeric qualifier, as in "LR(1)" or sometimes "LR(''k'')". To avoid backtracking or guessing, the LR parser is allowed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 computer science. Knuth has been called the "father of the analysis of algorithms". Knuth is the author of the multi-volume work '' The Art of Computer Programming''. He contributed to the development of the rigorous analysis of the computational complexity of algorithms and systematized formal mathematical techniques for it. In the process, he also popularized the asymptotic notation. In addition to fundamental contributions in several branches of theoretical computer science, Knuth is the creator of the TeX computer typesetting system, the related METAFONT font definition language and rendering system, and the Computer Modern family of typefaces. As a writer and scholar, Knuth created the WEB and CWEB computer programming systems des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B (programming Language)
B is a programming language developed at Bell Labs circa 1969 by Ken Thompson and Dennis Ritchie. B was derived from BCPL, and its name may possibly be a contraction of BCPL. Thompson's coworker Dennis Ritchie speculated that the name might be based on Bon, an earlier, but unrelated, programming language that Thompson designed for use on Multics. B was designed for recursive, non-numeric, machine-independent applications, such as system and language software. It was a typeless language, with the only data type being the underlying machine's natural memory word format, whatever that might be. Depending on the context, the word was treated either as an integer or a memory address. As machines with ASCII processing became common, notably the DEC PDP-11 that arrived at Bell Labs, support for character data stuffed in memory words became important. The typeless nature of the language was seen as a disadvantage, which led Thompson and Ritchie to develop an expanded version of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 (one is true, one is false). With multiple inputs, XOR is true if and only if the number of true inputs is odd. It gains the name "exclusive or" because the meaning of "or" is ambiguous when both operands are true. XOR ''excludes'' that case. Some informal ways of describing XOR are "one or the other but not both", "either one or the other", and "A or B, but not A and B". It is symbolized by the prefix operator J Translated as and by the infix operators XOR (, , or ), EOR, EXOR, \dot, \overline, \underline, , \oplus, \nleftrightarrow, and \not\equiv. Definition The truth table of A\nleftrightarrow B shows that it outputs true whenever the inputs differ: Equivalences, elimination, and introduction Exclusive disjunction essentially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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, and 4. System V Release 4 (SVR4) was commercially the most successful version, being the result of an effort, marketed as ''Unix System Unification'', which solicited the collaboration of the major Unix vendors. It was the source of several common commercial Unix features. System V is sometimes abbreviated to SysV. , the AT&T-derived Unix market is divided between four System V variants: IBM's AIX, Hewlett Packard Enterprise's HP-UX and Oracle's Solaris, plus the free-software illumos forked from OpenSolaris. Overview Introduction System V was the successor to 1982's UNIX System III. While AT&T developed and sold hardware that ran System V, most customers ran a version from a reseller, based on AT&T's reference implementation. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
