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30-611: The DCC protocol is defined by the Digital Command Control Working group of the US National Model Railroad Association (NMRA). The NMRA has trademarked the term DCC, so while the term Digital Command Control is sometimes used to describe any digital model railway control system, strictly speaking it refers to NMRA DCC. A digital command control system was developed (under contract by Lenz Elektronik GmbH of Germany) in

60-439: A DCC signal. The great advantage of digital control is the individual control of locomotives wherever they are on the layout. With analog control, operating more than one locomotive independently requires the track to be wired into separate blocks each having switches to select the controller. Using digital control, locomotives may be controlled wherever they are. Digital locomotive decoders often include inertia simulation, where

90-554: A conventional DC powered layout. With digital control of accessories, the wiring is distributed to accessory decoders rather than being individually connected to a central control panel. For portable layouts this can greatly reduce the number of inter-board connections - only the digital signal and any accessory power supplies need cross baseboard joins. [REDACTED] There are two main European alternatives: Selectrix , an open Normen Europäischer Modellbahnen (NEM) standard, and

120-726: A partitioning to several regions according to the mathematical structure it has. In the case of total order , as for memory addresses , these are simply chunks . Like the hierarchical design of postal addresses , some nested domain hierarchies appear as a directed ordered tree , such as with the Domain Name System or a directory structure . In the Internet , the Internet Assigned Numbers Authority (IANA) allocates ranges of IP addresses to various registries so each can manage their parts of

150-939: Is a non-profit organization for those involved in the hobby or business of model railroading . It was founded in the United States in 1935, and is also active in Canada , Australia , the United Kingdom , and the Netherlands . It was previously headquartered in Indianapolis, Indiana , and was based in Chattanooga, Tennessee next to the Tennessee Valley Railroad Museum (TVRM) from 1982 to 2013 and has since relocated to Soddy Daisy . The classifications listed below are from

180-411: Is a pure digital signal, described as a differential signal with no ground reference. One rail is always the inverse logical state of the other, with each data pulse repeated. The DCC signal does not follow a sine wave , nor is it a carrier superimposed on a DC voltage. The command station/booster quickly switches the voltage applied to the rails on and off, resulting in a binary stream of pulses. As there

210-659: Is home of the A.C. Kalmbach Memorial Library, which houses model and prototype railroad books, periodicals, photos, videos, and reference materials, and was designated as the official railroad library of the state of Tennessee in 2004. In 2013 the NMRA started the process of moving the library to the California State Railroad Museum . The library was adjacent to the Norfolk Southern Railway Georgia Division and

240-541: Is known as zero stretching and is not part of the NMRA DCC Standard. The zero bit's period can be expanded (stretched) to make the average voltage (and thus the current) either forward or reverse, depending on which rail the stretched zero bit is applied to. However, because the raw power contains a large harmonic component, DC motors heat up much more quickly than they would on DC power, and some motor types (particularly coreless electric motors ) can be damaged by

270-408: Is no polarity, direction of travel is independent of the rail's state. The length of time the voltage is applied provides the method for encoding data. To represent a binary one, the period is short (nominally 106  μs ), while a zero is represented by a longer period (nominally at least 200 μs). Each locomotive is equipped with an individually addressed multifunction DCC decoder that takes

300-1031: The Märklin Digital proprietary system. The US Rail-Lynx system provides power with a fixed voltage to the rails while commands are sent digitally using infrared light . Other systems include the Digital Command System and Trainmaster Command Control . Several major manufacturers (including Märklin, Fleischmann , Roco , Hornby and Bachmann ), have entered the DCC market alongside makers which specialize in it (including Lenz, Digitrax, ESU, ZIMO, Kühn, Tams, NCE, Digikeijs, and CVP Products, Sound Traxx, Train Control Systems and ZTC). Most Selectrix central units are multi protocol units supporting DCC fully or partially (e.g. Rautenhaus, Stärz and MTTM). National Model Railroad Association The National Model Railroad Association ( NMRA )

330-578: The Tennessee Valley Railroad Museum . It is named for Al C. Kalmbach , founder of Kalmbach Publishing , whose original magazines are Model Railroader and Trains . Address space In computing , an address space defines a range of discrete addresses, each of which may correspond to a network host , peripheral device , disk sector , a memory cell or other logical or physical entity. For software programs to save and retrieve stored data, each datum must have an address where it can be located. The number of address spaces available depends on

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360-583: The address space would be a combination of locations, such as a neighborhood, town, city, or country. Some elements of a data address space may be the same, but if any element in the address is different, addresses in said space will reference different entities. For example, there could be multiple buildings at the same address of "32 Main Street" but in different towns, demonstrating that different towns have different, although similarly arranged, street address spaces. An address space usually provides (or allows)

390-509: The 1980s for two German model railway manufacturers, Märklin and Arnold . The first digital decoders that Lenz produced appeared on the market early 1989 for Arnold ( N scale ) and mid 1990 for Märklin ( Z scale , H0 scale and 1 gauge ; Digital=). Märklin and Arnold exited the agreement over patent issues, but Lenz continued to develop the system. In 1992 Stan Ames, who later chaired the NMRA/DCC Working Group, investigated

420-415: The A.A.R. Individual roads may use other designations. Illustrations show a typical member of the class detailed underneath the following a class description indicates a rare or obsolete type. The best-known activity of the NMRA is the defining of standards , and advisory documents known as Recommended Practices (RP), for model railroad equipment. Many standards defined by the NMRA are widely followed by

450-538: The DCC protocol to allow a feedback channel from decoders to the command station. This feedback channel can typically be used to signal which train occupies a certain section, but as well to inform the command station of the actual speed of an engine. This feedback channel is known under the name RailCom, and was standardized in 2007 as NMRA RP 9.3.1. Quoting "NMRA Standards and Recommended Practices": A DCC system consists of power supplies, command stations, boosters, throttles and decoders. The DCC command station creates

480-427: The DCC throttle. Accessory decoders can also receive commands from the throttle in a similar way to allow control of turnouts, uncouplers and other operating accessories (such as station announcements) and lights. It is possible to power a single analog (DC) model locomotive by itself (or in addition to the DCC decoder equipped engines), depending on the choice of commercially available DCC starter systems. The technique

510-594: The Hobby & NMRA Member. A full explanation of each program along with applications can be found on the NMRA website. Promotion of the model railroading hobby is also part of the NMRA's purpose. Of note, the organization provides indirect assistance to the Boy Scouts of America 's Railroading Merit badge program by encouraging members (through a hierarchy of National and Regional volunteer Boy Scout Coordinators) to become Railroading Merit Badge Counselors. The NMRA

540-580: The Lenz system and further extended it. The system was later named Digital Command Control. The first commercial systems built on the NMRA DCC were demonstrated at the 1993 NMRA Convention, when the proposed DCC Standard was announced. The proposed standard was published in the October 1993 issue of Model Railroader magazine prior to its adoption. The DCC protocol is the subject of two standards published by

570-634: The Märklin/Lenz system as possible candidate for the NMRA/DCC standards. When the NMRA Command Control committee requested submissions from manufacturers for its proposed command control standard in the 1990s, Märklin and Keller Engineering submitted their systems for evaluation. The committee was impressed by the Märklin/Lenz system and had settled on digital early in the process. The NMRA eventually developed their own protocol based on

600-643: The NMRA: S-9.1 specifies the electrical standard, and S-9.2 specifies the communications standard. Several recommended practices documents are also available. The DCC protocol defines signal levels and timings on the track. DCC does not specify the protocol used between the DCC command station and other components such as additional throttles. A variety of proprietary standards exist, and in general, command stations from one vendor are not compatible with throttles from another vendor. In 2006 Lenz, together with Kühn, Zimo and Tams, started development of an extension to

630-658: The RP. This is in marked contrast to the British market, in which there is no accepted standard among manufacturers. In Europe , the Normen Europäischer Modellbahnen (NEM) has the same role, and although there is fairly close cooperation between the two organisations the standards differ in some aspects. At times this results in some models not working as intended on layouts that mix European and American rolling stock and trackwork. The NMRA considers

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660-474: The digital packet using data from a throttle. The digital packet contains the decoder's address, instructions and an error byte to check the validity of the packet. Many command stations are integrated with an amplifier (booster) which, in combination with its power supply, modulates the voltage on the track to encode digital messages while providing electric power. For large systems additional boosters may be employed to provide extra power. The track voltage

690-459: The edge of different IP spaces, such as a local area network and the Internet. An iconic example of virtual-to-physical address translation is virtual memory , where different pages of virtual address space map either to page file or to main memory physical address space. It is possible that several numerically different virtual addresses all refer to one physical address and hence to

720-690: The education of model railroaders and the encouraging of learning and improving modelers' skills to be part of its mission. The NMRA runs an achievement program to encourage these skills, and runs modeling contests. Most notably these include the Master Model Railroader certification program and the Golden Spike award. Both programs involve the demonstration and/or judging of proficiency in one or more model railroading skill areas. These areas include Railroad Equipment, Railroad Setting, Railroad Construction & Operation and also Service to

750-502: The global Internet address space. Uses of addresses include, but are not limited to the following: Another common feature of address spaces are mappings and translations , often forming numerous layers. This usually means that some higher-level address must be translated to lower-level ones in some way. For example, a file system on a logical disk operates using linear sector numbers, which have to be translated to absolute LBA sector addresses, in simple cases, via addition of

780-461: The industry and modellers, including their H0 scale track and wheel standards (S-3, S-4) and related RPs (RP2, 8, 10-15, and 25) and their Digital Command Control (DCC) standard set (S-9.1, S-9.2, and RP9.1.1 through RP9.3.2). The RP25 wheel design in particular has been critical in ensuring the reliability and interoperability of US-prototype model railroad equipment, since practically every manufacturer of such equipment uses wheels conforming to

810-594: The locomotive will gradually increase or decrease speeds in a realistic manner. Many decoders will also constantly adjust motor power to maintain constant speed . Most digital controllers allow an operator to set the speed of one locomotive and then select another locomotive to control its speed while the previous locomotive maintains its speed. Recent developments include on-board sound modules for locomotives as small as N scale, made possible by advancements in smartphones , which tend to use small yet high-quality speakers. Wiring requirements are generally reduced compared to

840-645: The partition's first sector address. Then, for a disk drive connected via Parallel ATA , each of them must be converted to logical cylinder-head-sector address due to the interface historical shortcomings. It is converted back to LBA by the disk controller , then, finally, to physical cylinder , head and sector numbers. The Domain Name System maps its names to and from network-specific addresses (usually IP addresses), which in turn may be mapped to link layer network addresses via Address Resolution Protocol . Network address translation may also occur on

870-524: The signal from the track, processes and acts on the instructions. The electric motor 's speed and direction is controlled using pulse-width modulation . Each decoder is given a unique address , and will not act on commands intended for a different decoder, thus providing independent control of locomotives and accessories anywhere on the layout without special wiring requirements. Decoders can also control functions such as lights, smoke generators, and sound generators. These functions can be operated remotely from

900-486: The underlying address structure, which is usually limited by the computer architecture being used. Often an address space in a system with virtual memory corresponds to a highest level translation table, e.g., a segment table in IBM System/370 . Address spaces are created by combining enough uniquely identified qualifiers to make an address unambiguous within the address space. For a person's physical address,

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