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Quasi-delay-insensitive Circuit
A quasi-delay-insensitive circuit (QDI circuit) is an asynchronous circuit design methodology employed in digital logic design. Developed in response to the performance challenges of building sub-micron, multi-core architectures with conventional synchronous designs, QDI circuits exhibit lower power consumption, extremely fine-grain pipelining, high circuit robustness against process–voltage–temperature variations, on-demand (event-driven) operation, and data-dependent completion time. Overview Advantages * Robust against process variation, temperature fluctuation, circuit redesign, and FPGA remapping. * Natural event sequencing facilitates complex control circuitry. * Automatic clock gating and compute-dependent cycle time can save dynamic power and increase throughput by optimizing for average-case workload characteristics instead of worst-case. Disadvantages * Delay insensitive encodings generally require twice as many wires for the same data. * Communication protoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asynchronous Circuit
Asynchronous circuit (clockless or self-timed circuit) is a sequential logic, sequential digital logic electrical network, circuit that does not use a global clock circuit or clock signal, signal generator to synchronize its components. Instead, the components are driven by a handshaking circuit which indicates a completion of a set of instructions. Handshaking works by simple data transfer Communications protocol, protocols. Many synchronous circuits were developed in early 1950s as part of bigger asynchronous systems (e.g. ORDVAC). Asynchronous circuits and theory surrounding is a part of several steps in integrated circuit design, a field of digital electronics engineering. Asynchronous circuits are contrasted with synchronous circuits, in which changes to the signal values in the circuit are triggered by repetitive pulses called a clock signal. Most digital devices today use synchronous circuits. However asynchronous circuits have a potential to be much faster, have a lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AND Gate
The AND gate is a basic digital logic gate that implements the logical conjunction (∧) from mathematical logic AND gates behave according to their truth table. A HIGH output (1) results only if all the inputs to the AND gate are HIGH (1). If any of the inputs to the AND gate are not HIGH, a LOW (0) is outputted. The function can be extended to any number of inputs by multiple gates up in a chain. Symbols There are three symbols for AND gates: the American (ANSI or 'military') symbol and the IEC ('European' or 'rectangular') symbol, as well as the deprecated DIN symbol. Additional inputs can be added as needed. For more information see the Logic gate symbols article. It can also be denoted as symbol "^" or "&". The AND gate with inputs ''A'' and ''B'' and output ''C'' implements the logical expression C = A \cdot B. This expression also may be denoted as C=A \wedge B or C=A \And B. As of Unicode 16.0.0, the AND gate is also encoded in the Symbols for Legacy Computing Su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C-element
In Logic gate, digital computing, the Muller C-element (C-gate, hysteresis flip-flop, coincident flip-flop, or two-hand safety circuit) is a small binary sequential logic, logic circuit widely used in design of asynchronous circuits and systems. It outputs 0 when all inputs are 0, it outputs 1 when all inputs are 1, and it retains its output state otherwise. It was specified formally in 1955 by David E. MullerD. E. MullerTheory of asynchronous circuits Report no. 66, Digital Computer Laboratory, University of Illinois at Urbana-Champaign, 1955. and first used in ILLIAC II computer. In terms of the theory of Lattice (order), lattices, the C-element is a semimodular distributive circuit, whose operation in time is described by a Hasse diagram.D. E. Muller and W. S. Bartky"A theory of asynchronous circuits" Int. Symposium on the Switching Theory in Harvard University, pp. 204–243, 1959. The C-element is closely related to the ''rendezvous'' and ''join'' elements, where an input is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipartite Graph
In the mathematics, mathematical field of graph theory, a bipartite graph (or bigraph) is a Graph (discrete mathematics), graph whose vertex (graph theory), vertices can be divided into two disjoint sets, disjoint and Independent set (graph theory), independent sets U and V, that is, every edge (graph theory), edge connects a Vertex (graph theory), vertex in U to one in V. Vertex sets U and V are usually called the ''parts'' of the graph. Equivalently, a bipartite graph is a graph that does not contain any odd-length cycle (graph theory), cycles. The two sets U and V may be thought of as a graph coloring, coloring of the graph with two colors: if one colors all nodes in U blue, and all nodes in V red, each edge has endpoints of differing colors, as is required in the graph coloring problem.. In contrast, such a coloring is impossible in the case of a non-bipartite graph, such as a Gallery of named graphs, triangle: after one node is colored blue and another red, the third vertex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boolean Expression
In computer science, a Boolean expression (also known as logical expression) is an expression used in programming languages that produces a Boolean value when evaluated. A Boolean value is either true or false. A Boolean expression may be composed of a combination of the Boolean constants True/False or Yes/No, Boolean-typed variables, Boolean-valued operators, and Boolean-valued functions. Boolean expressions correspond to propositional formulas in logic and are associated to Boolean circuits. Boolean operators Most programming languages have the Boolean operators OR, AND and NOT; in C and some languages inspired by it, these are represented by ", , " (double pipe character), "&&" (double ampersand) and "!" ( exclamation point) respectively, while the corresponding bitwise operations are represented by ", ", "&" and "~" (tilde).E.g. for Java see . In the mathematical literature the symbols used are often "+" ( plus), "·" ( dot) and overbar, or "∨" ( vel), "∧" ( et ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guarded Command Language
The Guarded Command Language (GCL) is a programming language defined by Edsger Dijkstra for predicate transformer semantics in EWD472. It combines programming concepts in a compact way. It makes it easier to develop a program and its proof hand-in-hand, with the proof ideas leading the way; moreover, parts of a program can actually be ''calculated''. An important property of GCL is nondeterminism. For example, in the if-statement, several alternatives may be true, and the choice is made at runtime, when the if-statement is executed. This frees the programmer from having to make unnecessary choices and is an aid in the formal development of programs. GCL includes the multiple assignment statement. For example, execution of the statement is done by first evaluating the righthand side values and then storing them in the lefthand variables. Thus, this statement swaps the values of and . The following books discuss the development of programs using GCL: * * * * * Guarded comma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communicating Sequential Processes
In computer science, communicating sequential processes (CSP) is a formal language for describing patterns of interaction in concurrent systems. It is a member of the family of mathematical theories of concurrency known as process algebras, or process calculi, based on message passing via channels. CSP was highly influential in the design of the occam programming language and also influenced the design of programming languages such as Limbo, RaftLib, Erlang (programming language), Erlang, Go (programming language), Go, Crystal (programming language), Crystal, and Clojure's core.async. CSP was first described by Tony Hoare in a 1978 article, and has since evolved substantially. CSP has been practically applied in industry as a tool for formal specification, specifying and verifying the concurrent aspects of a variety of different systems, such as the T9000 Transputer, as well as a secure e-commerce system. The theory of CSP itself is also still the subject of active research, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tony Hoare
Sir Charles Antony Richard Hoare (; born 11 January 1934), also known as C. A. R. Hoare, is a British computer scientist who has made foundational contributions to programming languages, algorithms, operating systems, formal verification, and concurrent computing. His work earned him the Turing Award, usually regarded as the highest distinction in computer science, in 1980. Hoare developed the sorting algorithm quicksort in 1959–1960. He developed Hoare logic, an axiomatic basis for verifying program correctness. In the semantics of concurrency, he introduced the formal language communicating sequential processes (CSP) to specify the interactions of concurrent processes, and along with Edsger Dijkstra, formulated the dining philosophers problem. Since 1977, he has held positions at the University of Oxford and Microsoft Research in Cambridge. Education and early life Tony Hoare was born in Colombo, Ceylon (now Sri Lanka) to British parents; his father was a colonial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Short Circuit
A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit. The opposite of a short circuit is an open circuit, which is an infinite resistance (or very high impedance) between two nodes. Definition A short circuit is an abnormal connection between two nodes of an electric circuit intended to be at different voltages. This results in an electric current limited only by the Thévenin equivalent resistance of the rest of the network which can cause circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, for the purpose of voltage-sensing crowbar circuit protectors. In circuit analysis, a ''short circuit'' is defined as a connection between two nodes that forces them to be at the sam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hazard (logic)
In digital logic, a hazard is an undesirable effect caused by either a deficiency in the system or external influences in both synchronous circuit, synchronous and asynchronous circuits. Logic hazards are manifestations of a problem in which changes in the input variables do not change the output correctly due to some form of delay caused by logic elements (NOT gate, NOT, AND gate, AND, OR gates, etc.) This results in the logic not performing its function properly. The three different most common kinds of hazards are usually referred to as static, dynamic and function hazards. Hazards are a temporary problem, as the logic circuit will eventually settle to the desired function. Therefore, in synchronous designs, it is standard practice to flip-flop (electronics), register the output of a circuit before it is being used in a different clock domain or routed out of the system, so that hazards do not cause any problems. If that is not the case, however, it is imperative that hazard ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
