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Arbiter (electronics)
Arbiters are electronic devices that allocate access to shared resources. Bus arbiter A bus arbiter is a device used in a multi-master bus system to decide which bus master will be allowed to control the bus for each bus cycle. The most common kind of bus arbiter is the memory arbiter in a system bus system. A memory arbiter is a device used in a shared memory system to decide, for each memory cycle, which CPU will be allowed to access that shared memory. Some atomic instructions depend on the arbiter to prevent other CPUs from reading memory "halfway through" atomic read-modify-write instructions. A memory arbiter is typically integrated into the memory controller/DMA controller. Some systems, such as conventional PCI, have a single centralized bus arbitration device that one can point to as "the" bus arbiter. Other systems use decentralized bus arbitration, where all the devices cooperate to decide who goes next. When every CPU connected to the memory arbiter has synch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bus (computing)
In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This expression covers all related hardware components (wire, optical fiber, etc.) and software, including communication protocols. Early computer buses were parallel electrical wires with multiple hardware connections, but the term is now used for any physical arrangement that provides the same logical function as a parallel electrical busbar. Modern computer buses can use both parallel and bit serial connections, and can be wired in either a multidrop (electrical parallel) or daisy chain topology, or connected by switched hubs, as in the case of Universal Serial Bus (USB). Background and nomenclature Computer systems generally consist of three main parts: * The central processing unit (CPU) that processes data, * The memory that holds the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jo Ebergen
Jo, jo, JO, or J.O. may refer to: Arts and entertainment * ''Jo'' (film), a 1972 French comedy * ''Jo'' (TV series), a French TV series *"Jo", a song by Goldfrapp from ''Tales of Us'' *"Jo", a song by Mr. Oizo from ''Lambs Anger'' * Jo a fictional character in the ''Star Wars'' franchise People * Jo (given name) * Jô, Brazilian footballer João Alves de Assis Silva (born 1987) * Josiel Alves de Oliveira (born 1988), Brazilian footballer also known as Jô * Jō (surname), a Japanese surname * Cho (Korean name), a common Korean surname which can be romanized as Jo Codes * JO, ISO 3166 country code for Jordan * .jo, the Internet country code top-level domain for Jordan * JO, IATA code for JALways, a subsidiary of Japan Airlines Other uses * '' jō'' (), a wooden staff used in some Japanese martial arts * ''jō'' (), a Japanese unit of length equivalent to the Chinese zhang * ''jō'' (), a Japanese unit of area corresponding to the area of a standard tatami mat (1×½ ken or 18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wavefront Arbiter
A Wavefront arbiter is a circuit used to make decisions which control the crossbar of a high capacity switch fabric in parallel. It was commercialized in the TT1 and TTx chip sets designed by Abrizio and sold by PMC-Sierra. Context A crossbar is the central portion of a crossbar switch fabric which connects the inputs to the outputs. A set of decisions of which inputs are connected to which outputs must be made each arbitration period. In high speed cell switching or packet switching applications, the arbitration period is very short. There are often millions or billions of arbitration periods per second. An arbiter is the circuit that makes the decision as to which of the crossbar's many switches should be closed. Speed is a key design criterion of an arbiter in some applications. Algorithm description A wavefront arbiter is a particular type of arbiter that is optimized for high-speed operation. For a unicast switch, the algorithm is as follows: # The decision starts at a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Race Conditions
A race condition or race hazard is the condition of an electronics, software, or other system where the system's substantive behavior is dependent on the sequence or timing of other uncontrollable events. It becomes a bug when one or more of the possible behaviors is undesirable. The term ''race condition'' was already in use by 1954, for example in David A. Huffman's doctoral thesis "The synthesis of sequential switching circuits". Race conditions can occur especially in logic circuits, multithreaded, or distributed software programs. In electronics A typical example of a race condition may occur when a logic gate combines signals that have traveled along different paths from the same source. The inputs to the gate can change at slightly different times in response to a change in the source signal. The output may, for a brief period, change to an unwanted state before settling back to the designed state. Certain systems can tolerate such glitches but if this output function ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multi-processor
Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. There are many variations on this basic theme, and the definition of multiprocessing can vary with context, mostly as a function of how CPUs are defined ( multiple cores on one die, multiple dies in one package, multiple packages in one system unit, etc.). According to some on-line dictionaries, a multiprocessor is a computer system having two or more processing units (multiple processors) each sharing main memory and peripherals, in order to simultaneously process programs. A 2009 textbook defined multiprocessor system similarly, but noting that the processors may share "some or all of the system’s memory and I/O facilities"; it also gave tightly coupled system as a synonymous term. At the operating system level, ''multiprocessing'' is some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gate Delay
Propagation delay is the time duration taken for a signal to reach its destination. It can relate to networking, electronics or physics. ''Hold time'' is the minimum interval required for the logic level to remain on the input after triggering edge of the clock pulse. Networking In computer networks, propagation delay is the amount of time it takes for the head of the signal to travel from the sender to the receiver. It can be computed as the ratio between the link length and the propagation speed over the specific medium. Propagation delay is equal to ''d / s'' where ''d'' is the distance and ''s'' is the wave propagation speed. In wireless communication, ''s''=''c'', i.e. the speed of light. In copper wire, the speed ''s'' generally ranges from .59c to .77c. This delay is the major obstacle in the development of high-speed computers and is called the interconnect bottleneck in IC systems. Electronics In electronics, digital circuits and digital electronics, the propagati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buridan's Principle
Buridan's ass is an illustration of a paradox in philosophy in the conception of free will. It refers to a hypothetical situation wherein an ass (donkey) that is equally hungry and thirsty is placed precisely midway between a stack of hay and a pail of water. Since the paradox assumes the donkey will always go to whichever is closer, it dies of both hunger and thirst since it cannot make any rational decision between the hay and water. A common variant of the paradox substitutes two identical piles of hay for the hay and water; the ass, unable to choose between the two, dies of hunger. The paradox is named after the 14th-century French philosopher Jean Buridan, whose philosophy of moral determinism it satirizes. Although the illustration is named after Buridan, philosophers have discussed the concept before him, notably Aristotle, who put forward the example of a man equally hungry and thirsty, and Al-Ghazali, who used a man faced with the choice of equally good dates. A version ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metastability In Electronics
In electronics, metastability is the ability of a digital electronic system to persist for an unbounded time in an unstable equilibrium or metastable state. In digital logic circuits, a digital signal is required to be within certain voltage or current limits to represent a '0' or '1' logic level for correct circuit operation; if the signal is within a forbidden intermediate range it may cause faulty behavior in logic gates the signal is applied to. In metastable states, the circuit may be unable to settle into a stable '0' or '1' logic level within the time required for proper circuit operation. As a result, the circuit can act in unpredictable ways, and may lead to a system failure, sometimes referred to as a "glitch". Metastability is an instance of the Buridan's ass paradox. Metastable states are inherent features of asynchronous digital systems, and of systems with more than one independent clock domain. In self-timed asynchronous systems, arbiters are designed to allo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metastability In Electronics
In electronics, metastability is the ability of a digital electronic system to persist for an unbounded time in an unstable equilibrium or metastable state. In digital logic circuits, a digital signal is required to be within certain voltage or current limits to represent a '0' or '1' logic level for correct circuit operation; if the signal is within a forbidden intermediate range it may cause faulty behavior in logic gates the signal is applied to. In metastable states, the circuit may be unable to settle into a stable '0' or '1' logic level within the time required for proper circuit operation. As a result, the circuit can act in unpredictable ways, and may lead to a system failure, sometimes referred to as a "glitch". Metastability is an instance of the Buridan's ass paradox. Metastable states are inherent features of asynchronous digital systems, and of systems with more than one independent clock domain. In self-timed asynchronous systems, arbiters are designed to allo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Femtoseconds
A femtosecond is a unit of time in the International System of Units (SI) equal to 10 or of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. For context, a femtosecond is to a second as a second is to about 31.71 million years; a ray of light travels approximately 0.3 μm (micrometers) in 1 femtosecond, a distance comparable to the diameter of a virus.Compared with overview in: Page 3 The word ''femtosecond'' is formed by the SI prefix ''femto'' and the SI unit ''second''. Its symbol is fs. A femtosecond is equal to 1000 attoseconds, or 1/1000 picosecond. Because the next higher SI unit is 1000 times larger, times of 10−14 and 10−13 seconds are typically expressed as tens or hundreds of femtoseconds. * Typical time steps for molecular dynamics simulations are on the order of 1 fs. * The periods of the waves of visible light have a duration of about 2 femtoseconds. = = 2.0 \times 10^~ The precise duration depends on the ener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flip-flop (electronics)
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information – a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Flip-flops and latches are fundamental building blocks of digital electronics systems used in computers, communications, and many other types of systems. Flip-flops and latches are used as data storage elements. A flip-flop is a device which stores a single ''bit'' (binary digit) of data; one of its two states represents a "one" and the other represents a "zero". Such data storage can be used for storage of ''state'', and such a circuit is described as sequential logic in electronics. When used in a finite-state machine, the output and next state depend not only on its current input, but also on its current state (and hence, previous inputs). It can also b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific American
''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it is the oldest continuously published magazine in the United States. ''Scientific American'' is owned by Springer Nature, which in turn is a subsidiary of Holtzbrinck Publishing Group. History ''Scientific American'' was founded by inventor and publisher Rufus Porter (painter), Rufus Porter in 1845 as a four-page weekly newspaper. The first issue of the large format newspaper was released August 28, 1845. Throughout its early years, much emphasis was placed on reports of what was going on at the United States Patent and Trademark Office, U.S. Patent Office. It also reported on a broad range of inventions including perpetual motion machines, an 1860 device for buoying vessels by Abraham Lincoln, and the universal joint which now can be found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
