Index: A-B | C-D | E-H | I-L | M-O | P-S | T-Z P º Packet-switching º Personal Computer or PC º Personal Digital Assistant (PDA) º Postal Telegraphy º Presidential Election, 1876 º Printing Receiver º Protocol for Packet Network Intercommunication, A º Punch-tape, Punch-card R º Real Time º Receiver º Relay º Right-of-way º Roberts, Larry (1937- ) º Rotary Press º Rotenberg, Marc (1960- ) º Rothschild Banking Dynasty º Router S º SAGE º Shannon, Claude (1916-2001) º Signal Key º Silicon º Smarr, Larry (1950- ) º Sounder º Speed Competition º Sputnik º Stock Ticker

 

P Packet-switching Technique for transmitting information across a network. In a packet-switched network, every message is broken down into small packets of information, around each of which is an "envelope" of information regarding its destination and its position in the original message. The packets are sent through the network independently of each other, increasing transmission efficiency. It is contrasted with circuit-switching. Personal Computer or PC Computers that are small enough and cheap enough to be bought and used by individuals and small businesses. First developed during the late 1970s, personal computers used the new microprocessors developed earlier in that decade. Personal computers became widely used in the 1980s both in business and in the home, and by the 1990s people had begun to connect them to each other via local area networks and the Internet. Personal Digital Assistant (PDA) A hand-held computer, typically used as a calendar and address book. Many personal digital assistants now have the ability to connect to the Internet via a wireless modem, allowing users to send and receive email and to browse the World Wide Web. Postal Telegraphy A system in which the government operates the telegraph as a branch of the post office. In the 19th and 20th centuries, most countries had postal telegraph systems: the U. S. was the only major industrial country in which private corporations owned and operated the national telegraph system. American progressive reformers periodically campaigned to have the federal government take over the industry, but Western Union successfully resisted all such efforts. Presidential Election, 1876 Disputed election between Rutherford B. Hayes (Republican) and Samuel Tilden (Democrat). Tilden won the popular vote, but the Electoral College vote was disputed and an Electoral Commission awarded the election to Hayes. Printing Receiver A device that receives telegraphic transmissions by printing them out on paper tape. Some receivers printed out Morse Code dots and dashes on a ribbon of paper tape; others printed uncoded alphabetic messages. Protocol for Packet Network Intercommunication, A Paper: "A Protocol for Packet network Intercommunication" Authors: Cerf, Vinton and Kahn, Robert: Computer scientists best known as co-authors of the TCP/IP protocols for inter-network communication. Punch-tape, Punch-card A roll of paper tape (or a paper card) used to store information to be read by a machine. Punch-tapes were widely used during the telegraph era and both punch tapes and punch cards were used with early computers. They were replaced first by magnetic tape and then by other forms of electronic storage, such as diskettes and CD-ROMs. [Back] [Index] [Close]

 

R Real Time A measure of time defined relative to the task at hand. Something happens in real time if it happens in time for the next step in a process to take place without delay. For example, a missile warning system operates in real time if it provides warnings in time for an effective response; a word processing program operates in real time if the human user cannot detect a lag between his or her typing and the appearance of letters on the screen. Receiver In telegraphy, a device that receives a telegraphic transmission. In 19th century Morse telegraphy, there were a variety of methods by which messages could be received. Some receivers printed out the Morse Code on paper tape; some embossed the code; others punched dots and dashes; still others only made audible clicks (sounders). See printing receiver. Relay In telegraphy, a device that receives a message and automatically sends it on. The relay was developed because signals diminish in strength over long distances. A relay receives a message at an intermediate location, before it becomes degraded, and then re-sends it at full strength. Also known as a repeater. Right-of-way In order to put up telegraph poles and wires, telegraph companies first had to secure the legal right to do so, which was called right-of-way. Because the purchase of such rights could be costly and time consuming, telegraph companies usually made cooperative arrangements with railroad companies to locate telegraph lines along railroad lines. Roberts, Larry (1937- ) Computer scientist and electrical engineer in charge of the design and construction of the ARPANET from 1967 to 1973. Rotary Press Device invented in the early 19th century that enabled very rapid printing of newspapers, magazines, books, etc. Rotenberg, Marc (1960- ) Lawyer and executive director of EPIC, the Electronic Privacy Information Center, an organization devoted to the protection of privacy rights in the Internet age. Rothschild Banking Dynasty Founded by Mayer Amschel Rothschild in the late 18th century, the Rothschild banking dynasty exerted great influence on the economic and political history of Europe for over 200 years, with branches in Frankfurt, London, Paris, Vienna, and Naples. Router Device used to route packets of information through the Internet. [Back] [Index] [Close]

 

S SAGE Semi-Automatic Ground Environment. A computerized air-defense system created by the U. S. Air Force during the late 1950s and early 1960s. SAGE spurred the advance of both computing and communications technology. Shannon, Claude (1916-2001) Mathematician and electrical engineer who created many of the fundamental concepts of computer science and communications theory. By recognizing that all information could be encoded in binary digits or bits, Shannon revolutionized computation and communications. Signal Key In telegraphy, a sending device used to tap out messages in Morse code. Also called key. Silicon Basic material used in the construction of integrated circuits and microprocessors today. Silicon is plentiful (it is the primary element in sand) and inexpensive, which has helped keep the costs of computers low. Smarr, Larry (1950- ) Astronomer and computer scientist who headed the National Center for Supercomputing Applications (NCSA) at the University of Illinois-Champaign for most of the 1980s and 1990s. Under his leadership, NCSA staff developed software that made the Internet easier to use, such as Telnet and Mosaic. Sounder In Morse telegraphy, a device that receives a transmission by making audible clicks that specially trained operators can decode in real time. Speed Competition Morse telegraphers took great pride in their ability to rapidly send and decode messages. In the late 19th century, telegraph companies and unions sponsored speed competitions in which operators vied for cash prizes. Sputnik Sputnik I was the Earth's first artificial satellite, launched in October of 1957 by the Soviet Union. The launch of Sputnik alarmed American leaders who began to fear that the United States was falling behind the Soviet Union in the arms race. Stock Ticker A high-speed printing telegraph used for reporting the fluctuation of prices on stock and commodity exchanges. Stock tickers printed the stock symbol, number of shares, and price of each transaction on a ribbon of paper tape. Although printing telegraphs were already in use at some commodity and stock exchanges, in the late 1860s and early 1870s Thomas Alva Edison devised an improved and reliable device, the Universal Printing Telegraph, that was in many respects a breakthrough. [Back] [Index] [Close]