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Elaine M. McGraw
Elaine M. McGraw (née Boehme) was an American computer programmer who, together with Arthur Samuel and Gene Amdahl, invented open addressing based hash tables in 1954. After studying economics, McGraw began working as a computer programmer for The Prudential Life Insurance Company in the early 1950s, using a UNIVAC computer. Prudential sent her to IBM to learn how to program the IBM 701, but (believing that Prudential would not purchase this computer) she applied for a job at IBM, and was hired there in 1953 by Gene Amdahl. She continued to work at IBM until at least 1970.. In 1954, McGraw was working with Amdahl and Arthur Samuel on an assembler (a program for converting a textual description of a sequence of computer instructions into machine code) and she was tasked with implementing a symbol table for it. Together, Amdahl, McGraw, and Samuel solved this problem by inventing the methods of open addressing and linear probing, still frequently used in modern hash table data st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programmer
A computer programmer, sometimes referred to as a software developer, a software engineer, a programmer or a coder, is a person who creates computer programs — often for larger computer software. A programmer is someone who writes/creates computer software or applications by providing a specific programming language to the computer. Most programmers have extensive computing and coding experience in many varieties of programming languages and platforms, such as Structured Query Language (SQL), Perl, Extensible Markup Language (XML), PHP, HTML, C, C++ and Java. A programmer's most often-used computer language (e.g., Assembly, C, C++, C#, JavaScript, Lisp, Python, Java, etc.) may be prefixed to the aforementioned terms. Some who work with web programming languages may also prefix their titles with ''web''. Terminology There is no industry-wide standard terminology, so "programmer" and "software engineer" might refer to the same role at different companies. Most typically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Samuel (computer Scientist)
Arthur Lee Samuel (December 5, 1901 – July 29, 1990) was an American pioneer in the field of computer gaming and artificial intelligence. He popularized the term "machine learning" in 1959. The Samuel Checkers-playing Program was among the world's first successful self-learning programs, and as such a very early demonstration of the fundamental concept of artificial intelligence (AI). He was also a senior member in the TeX community who devoted much time giving personal attention to the needs of users and wrote an early TeX manual in 1983. Biography Samuel was born on December 5, 1901, in Emporia, Kansas, and graduated from College of Emporia in Kansas in 1923. He received a master's degree in Electrical Engineering from MIT in 1926, and taught for two years as instructor. In 1928, he joined Bell Laboratories, where he worked mostly on vacuum tubes, including improvements of radar during World War II. He developed a gas-discharge transmit-receive switch (TR tube) that allow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Amdahl
Gene Myron Amdahl (November 16, 1922 – November 10, 2015) was an American computer architect and high-tech entrepreneur, chiefly known for his work on mainframe computers at IBM and later his own companies, especially Amdahl Corporation. He formulated Amdahl's law, which states a fundamental limitation of parallel computing. Childhood and education Amdahl was born to immigrant parents of Norwegian and Swedish descent in Flandreau, South Dakota. After serving in the Navy during World War II he completed a degree in engineering physics at South Dakota State University in 1948. He went on to study theoretical physics at the University of Wisconsin–Madison under Robert G. Sachs. However, in 1950, Amdahl and Charles H. "Charlie" Davidson, a fellow PhD student in the Department of Physics, approached Harold A. Peterson with the idea of a digital computer. Amdahl and Davidson gained the support of Peterson and fellow electrical engineering professor Vincent C. Rideout, who e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Addressing
Open addressing, or closed hashing, is a method of collision resolution in hash tables. With this method a hash collision is resolved by probing, or searching through alternative locations in the array (the ''probe sequence'') until either the target record is found, or an unused array slot is found, which indicates that there is no such key in the table. Well-known probe sequences include: ; Linear probing : in which the interval between probes is fixed — often set to 1. ; Quadratic probing : in which the interval between probes increases quadratically (hence, the indices are described by a quadratic function). ; Double hashing : in which the interval between probes is fixed for each record but is computed by another hash function. The main trade offs between these methods are that linear probing has the best cache performance but is most sensitive to clustering, while double hashing has poor cache performance but exhibits virtually no clustering; quadratic probing falls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hash Table
In computing, a hash table, also known as hash map, is a data structure that implements an associative array or dictionary. It is an abstract data type that maps keys to values. A hash table uses a hash function to compute an ''index'', also called a ''hash code'', into an array of ''buckets'' or ''slots'', from which the desired value can be found. During lookup, the key is hashed and the resulting hash indicates where the corresponding value is stored. Ideally, the hash function will assign each key to a unique bucket, but most hash table designs employ an imperfect hash function, which might cause hash ''collisions'' where the hash function generates the same index for more than one key. Such collisions are typically accommodated in some way. In a well-dimensioned hash table, the average time complexity for each lookup is independent of the number of elements stored in the table. Many hash table designs also allow arbitrary insertions and deletions of key–value pairs, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prudential Financial
Prudential Financial, Inc. is an American Fortune Global 500 and Fortune 500 company whose subsidiaries provide insurance, retirement planning, investment management, and other products and services to both retail and institutional customers throughout the United States and in over 40 other countries. In 2019, Prudential was the largest insurance provider in the United States with $815.1 billion in total assets. The company uses the Rock of Gibraltar as its logo. Logo The use of Prudential's symbol, the Rock of Gibraltar, began after an advertising agent passed Laurel Hill, a volcanic neck, in Secaucus, New Jersey, on a train in the 1890s. The related slogans "Get a Piece of the Rock" and "Strength of Gibraltar" are also still quite widely associated with Prudential, though current advertising uses neither of these. Through the years, the symbol went through various versions, but in 1989, a simplified pictogram symbol of the Rock of Gibraltar was adopted. It has been used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNIVAC
UNIVAC (Universal Automatic Computer) was a line of electronic digital stored-program computers starting with the products of the Eckert–Mauchly Computer Corporation. Later the name was applied to a division of the Remington Rand company and successor organizations. The BINAC, built by the Eckert–Mauchly Computer Corporation, was the first general-purpose computer for commercial use, but it was not a success. The last UNIVAC-badged computer was produced in 1986. History and structure J. Presper Eckert and John Mauchly built the ENIAC (Electronic Numerical Integrator and Computer) at the University of Pennsylvania's Moore School of Electrical Engineering between 1943 and 1946. A 1946 patent rights dispute with the university led Eckert and Mauchly to depart the Moore School to form the Electronic Control Company, later renamed Eckert–Mauchly Computer Corporation (EMCC), based in Philadelphia, Pennsylvania. That company first built a computer called BINAC (BINar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 701
The IBM 701 Electronic Data Processing Machine, known as the Defense Calculator while in development, was IBM’s first commercial scientific computer and its first series production mainframe computer, which was announced to the public on May 21, 1952. It was invented and developed by Jerrier Haddad and Nathaniel Rochester based on the IAS machine at Princeton. The IBM 701 was the first computer in the IBM 700/7000 series, which were IBM’s high-end computers until the arrival of the IBM System/360 in 1964. The business-oriented sibling of the 701 was the IBM 702 and a lower-cost general-purpose sibling was the IBM 650, which gained fame as the first mass-produced computer in the world. History IBM 701 competed with Remington Rand's UNIVAC 1103 in the scientific computation market, which had been developed for the NSA, so it was held secret until permission to market it was obtained in 1951. In early 1954, a committee of the Joint Chiefs of Staff requested that the two ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assembly Language
In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported. The first assembly code in which a language is used to represent machine code instructions is found in Kathleen and Andrew Donald Booth's 1947 work, ''Coding for A.R.C.''. Assembly code is converted into executable machine code by a utility program referred to as an ''assembler''. The term "assembler" is generally attributed to Wilkes, Wheeler and Gill in their 1951 book ''The Preparation of Programs for an Electronic Digital Com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Machine Code
In computer programming, machine code is any low-level programming language, consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). Each instruction causes the CPU to perform a very specific task, such as a load, a store, a jump, or an arithmetic logic unit (ALU) operation on one or more units of data in the CPU's registers or memory. Early CPUs had specific machine code that might break backwards compatibility with each new CPU released. The notion of an instruction set architecture (ISA) defines and specifies the behavior and encoding in memory of the instruction set of the system, without specifying its exact implementation. This acts as an abstraction layer, enabling compatibility within the same family of CPUs, so that machine code written or generated according to the ISA for the family will run on all CPUs in the family, including future CPUs. In general, each architecture family (e.g. x86, ARM) has its own ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbol Table
In computer science, a symbol table is a data structure used by a language translator such as a compiler or interpreter, where each identifier (or symbols), constants, procedures and functions in a program's source code is associated with information relating to its declaration or appearance in the source. In other words, the entries of a symbol table store the information related to the entry's corresponding symbol. Background A symbol table may only exist in memory during the translation process, or it may be embedded in the output of the translation, such as in an ABI object file for later use. For example, it might be used during an interactive debugging session, or as a resource for formatting a diagnostic report during or after execution of a program. Description The minimum information contained in a symbol table used by a translator and intermediate representation (IR) includes the symbol's name and its location or address. For a compiler targeting a platform with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Probing
Linear probing is a scheme in computer programming for resolving collisions in hash tables, data structures for maintaining a collection of key–value pairs and looking up the value associated with a given key. It was invented in 1954 by Gene Amdahl, Elaine M. McGraw, and Arthur Samuel and first analyzed in 1963 by Donald Knuth. Along with quadratic probing and double hashing, linear probing is a form of open addressing. In these schemes, each cell of a hash table stores a single key–value pair. When the hash function causes a collision by mapping a new key to a cell of the hash table that is already occupied by another key, linear probing searches the table for the closest following free location and inserts the new key there. Lookups are performed in the same way, by searching the table sequentially starting at the position given by the hash function, until finding a cell with a matching key or an empty cell. As write, "Hash tables are the most commonly used nontrivial d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
