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Edge-notched Card
Edge-notched cards or edge-punched cards are a system used to store a small amount of binary or logical data on paper index cards, encoded via the presence or absence of notches in the edges of the cards. The notches allow efficient sorting of a large number of cards in a paper-based database, as well as the selection of specific cards matching multiple desired criteria. Unlike machine-readable punched cards, edge-notched cards were designed to be manually sorted by human operators. They are also informally called needle cards since they can be sorted with the help of long knitting needles. In the mid-20th century they were sold under names such as Cope-Chat cards, E-Z Sort cards, McBee Keysort cards, and Indecks cards. History An early instance of a methodology similar to edge-notched cards appeared in 1904. Edge-notched cards were used for specialized data storage and cataloging through much of the 20th century. They were gradually replaced by computer storage. Formats Card ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hash Value
A hash function is any function that can be used to map data of arbitrary size to fixed-size values, though there are some hash functions that support variable-length output. The values returned by a hash function are called ''hash values'', ''hash codes'', (''hash/message'') ''digests'', or simply ''hashes''. The values are usually used to index a fixed-size table called a '' hash table''. Use of a hash function to index a hash table is called ''hashing'' or ''scatter-storage addressing''. Hash functions and their associated hash tables are used in data storage and retrieval applications to access data in a small and nearly constant time per retrieval. They require an amount of storage space only fractionally greater than the total space required for the data or records themselves. Hashing is a computationally- and storage-space-efficient form of data access that avoids the non-constant access time of ordered and unordered lists and structured trees, and the often-exponenti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bucket Sort
Bucket sort, or bin sort, is a sorting algorithm that works by distributing the elements of an Array data structure, array into a number of buckets. Each bucket is then sorted individually, either using a different sorting algorithm, or by recursively applying the bucket sorting algorithm. It is a distribution sort, a generalization of pigeonhole sort that allows multiple keys per bucket, and is a cousin of radix sort in the most-to-least significant digit flavor. Bucket sort can be implemented with comparisons and therefore can also be considered a comparison sort algorithm. The Analysis of algorithms, computational complexity depends on the algorithm used to sort each bucket, the number of buckets to use, and whether the input is uniformly distributed. Bucket sort works as follows: # Set up an array of initially empty "buckets". # Scatter: Go over the original array, putting each object in its bucket. # Sort each non-empty bucket. # Gather: Visit the buckets in order and put ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Democratic Republic
East Germany, officially known as the German Democratic Republic (GDR), was a country in Central Europe from Foundation of East Germany, its formation on 7 October 1949 until German reunification, its reunification with West Germany (FRG) on 3 October 1990. Until 1989, it was generally viewed as a communist state and described itself as a Socialist state, socialist "workers' and peasants' state". The Economy of East Germany, economy of the country was Central planning, centrally planned and government-owned corporation, state-owned. Although the GDR had to pay substantial war reparations to the Soviets, its economy became the most successful in the Eastern Bloc. Before its establishment, the country's territory was administered and occupied by Soviet forces following the Berlin Declaration (1945), Berlin Declaration abolishing German sovereignty in World War II. The Potsdam Agreement established the Soviet occupation zone in Germany, Soviet-occupied zone, bounded on the east b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A4 Paper
ISO 216 is an International Organization for Standardization, international standard for paper sizes, used around the world except in North America and parts of Latin America. The standard defines the "A", "B" and "C" series of paper sizes, which includes the A4, the most commonly available paper size worldwide. Two supplementary standards, ISO 217 and ISO 269, define related paper sizes; the ISO 269 "C" series is commonly listed alongside the A and B sizes. All ISO 216, ISO 217 and ISO 269 paper sizes (except some envelopes) have the same aspect ratio, square root of 2, , within rounding to millimetres. This ratio has the unique property that when cut or folded in half widthways, the halves also have the same aspect ratio. Each ISO paper size is one half of the area of the next larger size in the same series. Dimensions of A, B and C series History The oldest known mention of the advantages of basing a paper size on an aspect ratio of \sqrt is found in a letter writ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A7 Paper
ISO 216 is an international standard for paper sizes, used around the world except in North America and parts of Latin America. The standard defines the "A", "B" and "C" series of paper sizes, which includes the A4, the most commonly available paper size worldwide. Two supplementary standards, ISO 217 and ISO 269, define related paper sizes; the ISO 269 "C" series is commonly listed alongside the A and B sizes. All ISO 216, ISO 217 and ISO 269 paper sizes (except some envelopes) have the same aspect ratio, , within rounding to millimetres. This ratio has the unique property that when cut or folded in half widthways, the halves also have the same aspect ratio. Each ISO paper size is one half of the area of the next larger size in the same series. Dimensions of A, B and C series History The oldest known mention of the advantages of basing a paper size on an aspect ratio of \sqrt is found in a letter written on 25 October 1786 by the German scientist Georg Christoph L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technical Standard
A technical standard is an established Social norm, norm or requirement for a repeatable technical task which is applied to a common and repeated use of rules, conditions, guidelines or characteristics for products or related processes and production methods, and related management systems practices. A technical standard includes definition of terms; classification of components; delineation of procedures; specification of dimensions, materials, performance, designs, or operations; measurement of quality and quantity in describing materials, processes, products, systems, services, or practices; test methods and sampling procedures; or descriptions of fit and measurements of size or strength. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes, and practices. In contrast, a custom, convention, company product, corporate standard, and so forth that becomes generally accepted and dominant is often called a ''de facto'' standar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stasi
The Ministry for State Security (, ; abbreviated MfS), commonly known as the (, an abbreviation of ), was the Intelligence agency, state security service and secret police of East Germany from 1950 to 1990. It was one of the most repressive police organisations in the world, infiltrating almost every aspect of life in East Germany, using torture, intimidation and a vast network of informants to crush dissent. The function of the Stasi in East Germany (the GDR) resembled that of the KGB in the Soviet Union, in that it served to maintain state authority and the position of the ruling party, in this case the Socialist Unity Party of Germany (SED). This was accomplished primarily through the use of a network of civilian informants (called Unofficial collaborator, unofficial collaborators) who contributed to the arrest of approximately 250,000 people in East Germany. It also had a large elite paramilitary force, the Felix Dzerzhinsky Guards Regiment, that served as its armed wing. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codebreaking
Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown. In addition to mathematical analysis of cryptographic algorithms, cryptanalysis includes the study of side-channel attacks that do not target weaknesses in the cryptographic algorithms themselves, but instead exploit weaknesses in their implementation. Even though the goal has been the same, the methods and techniques of cryptanalysis have changed drastically through the history of cryptography, adapting to increasing cryptographic complexity, ranging from the pen-and-paper methods of the past, through machines like the British Bombes and Colossus computers at Bletchley Park in World War II, to the mathematically advanced comput ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal McBee
Royal Consumer Information Products, Inc. (formerly The Royal Typewriter Company) is an American technology company founded in January 1904 as a manufacturer of typewriters. Royal’s product line has evolved to include cash registers, shredders, personal digital assistants (PDAs)/electronic organizers, postal scales, weather stations, and a wide range of original and compatible/remanufactured imaging supplies supporting printers, faxes, and copiers. The company is headquartered in Hartford, Connecticut. History The Royal Typewriter Company was founded by Edward B. Hess and Lewis C. Myers in January 1904 in a machine shop in Brooklyn, New York. The next year, Hess and Myers turned to Thomas Fortune Ryan, to whom they demonstrated a prototype typewriter. Their machine had numerous innovations including a friction-free, ball-bearing, one-track rail to support the weight of the carriage, a new paper feed, a lighter and faster typebar action, and complete visibility of the words as t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Library Catalog
A library catalog (or library catalogue in British English) is a register of all bibliography, bibliographic items found in a library or group of libraries, such as a network of libraries at several locations. A catalog for a group of libraries is also called a union catalog. A bibliographic item can be any information entity (e.g., books, computer files, graphics, realia (library science), realia, cartographic materials, etc.) that is considered library material (e.g., a single novel in an anthology), or a group of library materials (e.g., a trilogy), or linked from the catalog (e.g., a webpage) as far as it is relevant to the catalog and to the users (patrons) of the library. The earliest library catalogs were lists, handwritten or enscribed on clay tablets and later scrolls of parchment or paper. As codex, codices (books with pages) replaced scrolls, so too did library catalogs become like handwritten ledgers and, in some cases, printed books. During the late 18th century ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
