GIO is a computer bus standard developed by SGI and used in a variety of their products in the 1990s as their primary expansion system. GIO was similar in concept to competing standards such as NuBus or (later) PCI , but saw little use outside SGI and severely limited the devices available on their platform as a result. Most devices using GIO were SGI's own graphics cards, although a number of cards supporting high-speed data access such as Fibre Channel and FDDI were available from third parties. Later SGI machines use the XIO bus, which is laid out as a computer network as opposed to a bus.
48-489: Like most busses of the era, GIO was a 32-bit address and data multiplexed bus that was normally clocked at 25 or 33 MHz. This meant that the bus uses the same path for addressing and data, thus normally requiring three cycles to transfer a single 32-bit value; one cycle to send the address, the next to send the data and then another to read or write it. This limited the bus to a maximum throughput of about 16 Mbyte /s at 33 MHz for these sorts of small transfers. However
96-425: A multiple-input multiple-output communications (MIMO) scheme. In wired communication, space-division multiplexing , also known as space-division multiple access (SDMA) is the use of separate point-to-point electrical conductors for each transmitted channel. Examples include an analog stereo audio cable, with one pair of wires for the left channel and another for the right channel, and a multi-pair telephone cable ,
144-423: A shared medium . The aim is to share a scarce resource – a physical transmission medium . For example, in telecommunications, several telephone calls may be carried using one wire. Multiplexing originated in telegraphy in the 1870s, and is now widely applied in communications. In telephony , George Owen Squier is credited with the development of telephone carrier multiplexing in 1910. The multiplexed signal
192-408: A time-multiplexing system of multiple Hughes machines in the 1870s. In 1874, the quadruplex telegraph developed by Thomas Edison transmitted two messages in each direction simultaneously, for a total of four messages transiting the same wire at the same time. Several researchers were investigating acoustic telegraphy , a frequency-division multiplexing technique, which led to the invention of
240-583: A cannon and directly after they left the cannon barrel. This was one of the earliest photonic programs. They also worked to develop synchronous AC telegraphic systems. His biggest contribution was that of telephone carrier multiplexing in 1910 for which he was elected to the National Academy of Sciences in 1919. He was also an elected member of the American Philosophical Society . In September 1900 Squier sailed from New York for Manila on
288-412: A customer's residential area, but the service provider can send multiple television channels or signals simultaneously over that cable to all subscribers without interference. Receivers must tune to the appropriate frequency (channel) to access the desired signal. A variant technology, called wavelength-division multiplexing (WDM) is used in optical communications . Time-division multiplexing (TDM)
336-446: A fashion similar to that of GIO32, with transfers being set up directly on the bus. The newer "pipelined" system was what the actual boards used, and as the name implies the system set up transfers in a several-step operation that was decoded in the controller's internal pipeline. Internally the non-pipelined bus transferred data between the various parts of the computer, including GIO cards, EISA devices, SCSI and so forth. GIO cards used
384-501: A new control pin, whereas GIO32 only supported the SGI-style big-endian addresses. Data could now be transferred 64-bits at a time thereby doubling the speed. GIO64 could also be run faster than GIO32, up to 40 MHz, providing a maximum streaming throughput of 320 Mbyte/s. The page sizes were also adjusted to allow for the changing CPU 's, starting at 4 kbyte for R3000 based machines, and up to 16 Mbyte for R4400 based ones. Physically
432-486: A peak bit rate of 54 Mbit/s, thus increasing the total peak bit rate by the factor k . Different antennas would give different multi-path propagation (echo) signatures, making it possible for digital signal processing techniques to separate different signals from each other. These techniques may also be utilized for space diversity (improved robustness to fading) or beamforming (improved selectivity) rather than multiplexing. Frequency-division multiplexing (FDM)
480-680: A service which piped music to businesses and subscribers over wires. In 1934, he changed the service's name to ' Muzak '. Asked how to say his name, he told The Literary Digest it was pronounced like the word square . He was a member of the Sons of the American Revolution . He died in Washington, D.C., at George Washington Hospital on March 24, 1934 of pneumonia , and was buried in Arlington National Cemetery . In 1943,
528-814: A single event loop , with system calls like poll and select (Unix) . Multiple variable bit rate digital bit streams may be transferred efficiently over a single fixed bandwidth channel by means of statistical multiplexing . This is an asynchronous mode time-domain multiplexing which is a form of time-division multiplexing. Digital bit streams can be transferred over an analog channel by means of code-division multiplexing techniques such as frequency-hopping spread spectrum (FHSS) and direct-sequence spread spectrum (DSSS). In wireless communications , multiplexing can also be accomplished through alternating polarization ( horizontal / vertical or clockwise / counterclockwise ) on each adjacent channel and satellite, or through phased multi-antenna array combined with
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#1732847492715576-539: A switched star network such as a telephone access network, a switched Ethernet network, and a mesh network . In wireless communication, space-division multiplexing is achieved with multiple antenna elements forming a phased array antenna . Examples are multiple-input and multiple-output (MIMO), single-input and multiple-output (SIMO) and multiple-input and single-output (MISO) multiplexing. An IEEE 802.11g wireless router with k antennas makes it in principle possible to communicate with k multiplexed channels, each with
624-481: A transport stream and/or container is commonly called a multiplexer or muxer . A demuxer is software that extracts or otherwise makes available for separate processing the components of such a stream or container. In digital television systems, several variable bit-rate data streams are multiplexed together to a fixed bit-rate transport stream by means of statistical multiplexing . This makes it possible to transfer several video and audio channels simultaneously over
672-412: Is a class of techniques where several channels simultaneously share the same frequency spectrum , and this spectral bandwidth is much higher than the bit rate or symbol rate . One form is frequency hopping, another is direct sequence spread spectrum. In the latter case, each channel transmits its bits as a coded channel-specific sequence of pulses called chips. Number of chips per bit, or chips per symbol,
720-405: Is a digital (or in rare cases, analog) technology that uses time, instead of space or frequency, to separate the different data streams. TDM involves sequencing groups of a few bits or bytes from each individual input stream, one after the other, and in such a way that they can be associated with the appropriate receiver. If done sufficiently quickly, the receiving devices will not detect that some of
768-439: Is a novel method for polarized antenna transmission utilizing a differential technique. Orbital angular momentum multiplexing is a relatively new and experimental technique for multiplexing multiple channels of signals carried using electromagnetic radiation over a single path. It can potentially be used in addition to other physical multiplexing methods to greatly expand the transmission capacity of such systems. As of 2012 it
816-795: Is a technique in which each channel transmits its bits as a coded channel-specific sequence of pulses. This coded transmission is typically accomplished by transmitting a unique time-dependent series of short pulses, which are placed within chip times within the larger bit time. All channels, each with a different code, can be transmitted on the same fiber and asynchronously demultiplexed. Other widely used multiple access techniques are time-division multiple access (TDMA) and frequency-division multiple access (FDMA). Code-division multiplex techniques are used as an access technology, namely code-division multiple access (CDMA), in Universal Mobile Telecommunications System (UMTS) standard for
864-405: Is inherently an analog technology. FDM achieves the combining of several signals into one medium by sending signals in several distinct frequency ranges over a single medium. In FDM the signals are electrical signals. One of the most common applications for FDM is traditional radio and television broadcasting from terrestrial, mobile or satellite stations, or cable television. Only one cable reaches
912-519: Is likewise also true for digital subscriber lines (DSL). Fiber in the loop (FITL) is a common method of multiplexing, which uses optical fiber as the backbone . It not only connects POTS phone lines with the rest of the PSTN , but also replaces DSL by connecting directly to Ethernet wired into the home . Asynchronous Transfer Mode is often the communications protocol used. Cable TV has long carried multiplexed television channels , and late in
960-461: Is not practical (such as where there are different sources using a single transponder ), single channel per carrier mode is used. In FM broadcasting and other analog radio media, multiplexing is a term commonly given to the process of adding subcarriers to the audio signal before it enters the transmitter , where modulation occurs. (In fact, the stereo multiplex signal can be generated using time-division multiplexing, by switching between
1008-454: Is one in which members share a number of ties stemming from more than one social context, such as workmates, neighbors, or relatives. George Owen Squier George Owen Squier (March 21, 1865 – March 24, 1934) was an American general, scientist, and inventor best known for inventing and popularizing what today is called Muzak . Squier was born in Dryden, Michigan . He graduated from
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#17328474927151056-717: Is possible (just as in statistical multiplexing ), that the wide bandwidth allows poor signal-to-noise ratio according to Shannon–Hartley theorem , and that multi-path propagation in wireless communication can be combated by rake receivers . A significant application of CDMA is the Global Positioning System (GPS). A multiplexing technique may be further extended into a multiple access method or channel access method , for example, TDM into time-division multiple access (TDMA) and statistical multiplexing into carrier-sense multiple access (CSMA). A multiple-access method makes it possible for several transmitters connected to
1104-420: Is still in its early research phase, with small-scale laboratory demonstrations of bandwidths of up to 2.5 Tbit/s over a single light path. This is a controversial subject in the academic community, with many claiming it is not a new method of multiplexing, but rather a special case of space-division multiplexing. Code-division multiplexing (CDM), code-division multiple access (CDMA) or spread spectrum
1152-418: Is the spreading factor . This coded transmission typically is accomplished by transmitting a unique time-dependent series of short pulses, which are placed within chip times within the larger bit time. All channels, each with a different code, can be transmitted on the same fiber or radio channel or other medium, and asynchronously demultiplexed. Advantages over conventional techniques are that variable bandwidth
1200-418: Is transmitted over a communication channel such as a cable. The multiplexing divides the capacity of the communication channel into several logical channels, one for each message signal or data stream to be transferred. A reverse process, known as demultiplexing, extracts the original channels on the receiver end. A device that performs the multiplexing is called a multiplexer (MUX), and a device that performs
1248-453: The Fourier transform principle. In computer programming , it may refer to using a single in-memory resource (such as a file handle) to handle multiple external resources (such as on-disk files). Some electrical multiplexing techniques do not require a physical " multiplexer " device, they refer to a " keyboard matrix " or " Charlieplexing " design style: In high-throughput DNA sequencing ,
1296-527: The United States Military Academy in the Class of 1887 and received a Ph.D. from Johns Hopkins University in 1893. He wrote and edited many books and articles on the subject of radio and electricity . An inventor, he and Dartmouth professor Albert Cushing Crehore developed a magneto-optical streak camera "The Polarizing Photo-chronograph" in 1896 to measure the speed of projectiles both inside
1344-504: The 20th century began offering the same services as telephone companies . IPTV also depends on multiplexing. In video editing and processing systems, multiplexing refers to the process of interleaving audio and video into one coherent data stream. In digital video , such a transport stream is normally a feature of a container format which may include metadata and other information, such as subtitles . The audio and video streams may have variable bit rate. Software that produces such
1392-485: The GIO64 bus used much larger cards that were generally similar in size and layout to EISA cards, a deliberate choice that made development somewhat easier as well as allowing SGI to place EISA slots in the same machines. Specifically the external connector (the metal flange) was identical to EISA, but the shape of the board itself was slightly different. Two versions of GIO64 were specified. The "non-pipelined" system worked in
1440-458: The airport ticket desk back to the airline data center are also installed. Some web proxy servers (e.g. polipo ) use TDM in HTTP pipelining of multiple HTTP transactions onto the same TCP/IP connection . Carrier-sense multiple access and multidrop communication methods are similar to time-division multiplexing in that multiple data streams are separated by time on the same medium, but because
1488-582: The cable ship USAT Burnside . He was in command of a 25-man Signal Corps detachment that laid the first American telegraph cables in the Philippines. As executive officer to the Chief Signal Officer, U.S. Signal Corps in 1907, Squier was instrumental in the establishment of the Aeronautical Division, U.S. Signal Corps , the first organizational ancestor of the U.S. Air Force . He also
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1536-446: The capacity to carry several HDTV channels in one multiplex. In digital radio , a multiplex (also known as an ensemble) is a number of radio stations that are grouped together. A multiplex is a stream of digital information that includes audio and other data. On communications satellites which carry broadcast television networks and radio networks , this is known as multiple channel per carrier or MCPC . Where multiplexing
1584-483: The cards lie at right angles to the motherboard . This led to a "tall and skinny" case design. Since the cards were "above" each other in-line, it was possible to build a card that connected to both connectors on the computer's motherboard, thereby offering more room. GIO was later expanded to a 64-bit form, GIO64 , retroactively renaming the earlier version GIO32 . Addressing remained 32-bit but now allowed for both big-endian and little-endian addressing as indicated by
1632-458: The case of CCITT7 signaling systems and 30 voice channels for customer-connected Q931, DASS2, DPNSS, V5 and CASS signaling systems. Polarization-division multiplexing uses the polarization of electromagnetic radiation to separate orthogonal channels. It is in practical use in both radio and optical communications, particularly in 100 Gbit/s per channel fiber-optic transmission systems . Differential Cross-Polarized Wireless Communications
1680-425: The circuit time was used to serve another logical communication path. Consider an application requiring four terminals at an airport to reach a central computer. Each terminal communicated at 2400 baud , so rather than acquire four individual circuits to carry such a low-speed transmission, the airline has installed a pair of multiplexers. A pair of 9600 baud modems and one dedicated analog communications circuit from
1728-452: The original GIO32, and tied "high" in GIO32-bis. For low-throughput cards, GIO32-bis allowed a single device to be used on any machine supporting GIO, no matter what generation. Multiplexed In telecommunications and computer networking , multiplexing (sometimes contracted to muxing ) is a method by which multiple analog or digital signals are combined into one signal over
1776-407: The pipelined controller to arbitrate and control timing, the data then being fed into main memory via the internal non-pipelined side. A third standard, GIO32-bis , used the signals and timing of GIO64, but with the 32-bit connectors from GIO32. Properly designed GIO32-bis cards could be used in GIO64, GIO32 or GIO32-bis slots, differentiating the later two by looking at a pin tied to the ground in
1824-422: The reverse process is called a demultiplexer (DEMUX or DMX). Inverse multiplexing (IMUX) has the opposite aim as multiplexing, namely to break one data stream into several streams, transfer them simultaneously over several communication channels, and recreate the original data stream. In computing , I/O multiplexing can also be used to refer to the concept of processing multiple input/output events from
1872-498: The same frequency channel, together with various services. This may involve several standard-definition television (SDTV) programs (particularly on DVB-T , DVB-S2 , ISDB and ATSC-C), or one HDTV , possibly with a single SDTV companion channel over one 6 to 8 MHz-wide TV channel. The device that accomplishes this is called a statistical multiplexer . In several of these systems, the multiplexing results in an MPEG transport stream . The newer DVB standards DVB-S2 and DVB-T2 has
1920-525: The same physical medium to share their capacity. Multiplexing is provided by the physical layer of the OSI model , while multiple access also involves a media access control protocol, which is part of the data link layer . The Transport layer in the OSI model, as well as TCP/IP model, provides statistical multiplexing of several application layer data flows to/from the same computer. Code-division multiplexing (CDM)
1968-576: The signals have separate origins instead of being combined into a single signal, are best viewed as channel access methods , rather than a form of multiplexing. TD is a legacy multiplexing technology still providing the backbone of most National fixed-line telephony networks in Europe, providing the 2 Mbit/s voice and signaling ports on narrow-band telephone exchanges such as the DMS100. Each E1 or 2 Mbit/s TDM port provides either 30 or 31 speech timeslots in
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2016-458: The system also included a long-burst read/write mode that allowed continual transfers of up to 4 kilobytes of data (the fundamental page size in R3000-based SGI machines); using this mode dramatically increased the throughput to 132 Mbyte/s (32 bits per cycle * 33 MHz). GIO also included a "real time" interrupt allowing devices to interrupt these long transfers if needed. Bus arbitration
2064-405: The telephone . In telephony , a customer 's telephone line now typically ends at the remote concentrator box, where it is multiplexed along with other telephone lines for that neighborhood or other similar area. The multiplexed signal is then carried to the central switching office on significantly fewer wires and for much further distances than a customer's line can practically go. This
2112-407: The term is used to indicate that some artificial sequences (often called barcodes or indexes ) have been added to link given sequence reads to a given sample, and thus allow for the sequencing of multiple samples in the same reaction. In sociolinguistics , multiplexity is used to describe the number of distinct connections between individuals who are part of a social network . A multiplex network
2160-479: The third-generation (3G) mobile communication identified by the ITU. The earliest communication technology using electrical wires, and therefore sharing an interest in the economies afforded by multiplexing, was the electric telegraph . Early experiments allowed two separate messages to travel in opposite directions simultaneously, first using an electric battery at both ends, then at only one end. Émile Baudot developed
2208-471: The two (left channel and right channel) input signals at an ultrasonic rate (the subcarrier), and then filtering out the higher harmonics.) Multiplexing in this sense is sometimes known as MPX , which in turn is also an old term for stereophonic FM, seen on stereo systems since the 1960s. In spectroscopy the term is used to indicate that the experiment is performed with a mixture of frequencies at once and their respective response unraveled afterward using
2256-520: Was controlled by the Processor Interface Controller ( PIC ) in the original R3000-based SGI Indigo systems. Physically, GIO used a 96-pin connector and fairly small cards 6.44 inches (16.3576 cm) long by 3.375 inches (8.5725 cm) wide. In the Indigo series, the cards were aligned vertically above each other within the case, as opposed to the more common arrangement where
2304-699: Was the first military passenger in an airplane on September 12, 1908, and, working with the Wright Brothers , was responsible for the purchase of the first airplanes by the US Army in 1909. From May 1916 to February 1917, he was Chief of the Aviation Section, U.S. Signal Corps , the first successor of the Aeronautical Division, before being promoted to major general and appointed Chief Signal Officer during World War I . In 1922, he created Wired Radio,
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