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Asynchronous System
The primary focus of this article is asynchronous control in digital electronic systems. In a synchronous system, operations ( instructions, calculations, logic, etc.) are coordinated by one, or more, centralized clock signals. An asynchronous system, in contrast, has no global clock. Asynchronous systems do not depend on strict arrival times of signals or messages for reliable operation. Coordination is achieved using event-driven architecture triggered by network packet arrival, changes (transitions) of signals, handshake protocols, and other methods. Modularity Asynchronous systems – much like object-oriented software – are typically constructed out of modular 'hardware objects', each with well-defined communication interfaces. These modules may operate at variable speeds, whether due to data-dependent processing, dynamic voltage scaling, or process variation. The modules can then be combined to form a correct working system, without reference to a global ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchronous System
In digital electronics, a synchronous circuit is a digital circuit in which the changes in the state of memory elements are synchronized by a clock signal. In a sequential digital logic circuit, data is stored in memory devices called flip-flops or latches. The output of a flip-flop is constant until a pulse is applied to its "clock" input, upon which the input of the flip-flop is latched into its output. In a synchronous logic circuit, an electronic oscillator called the ''clock'' generates a string (sequence) of pulses, the "clock signal". This clock signal is applied to every storage element, so in an ideal synchronous circuit, every change in the logical levels of its storage components is simultaneous. Ideally, the input to each storage element has reached its final value before the next clock occurs, so the behaviour of the whole circuit can be predicted exactly. Practically, some delay is required for each logical operation, resulting in a maximum speed limitations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
