Asynchrony

Asynchrony, in the general meaning, is the state of not being synchronized.
* Asynchronous learning
* Collaborative editing systems

In specific terms of digital logic and physical layer of communication, an asynchronous process does not require a clock signal. Contrast with plesiochronous systems.
* Asynchronous circuit
* Asynchronous system
* Asynchronous serial communication
** Asynchronous serial interfaces
* Asynchronous Cellular Automaton

At the higher data link layer of communication, asynchrony is synonym of statistical multiplexing, such as in packet mode. The information transmission may or may not start immediately as requested by sender, the additional delay being caused by medium congestion. Contrast with example of circuit switched communication, which (once circuit is established) allows immediate start of transfer with a guaranteed bit rate. Confusingly, a communication is often synchronous at the "physical" layer, while being asynchronous at the "data link" layer.
* Asynchronous Transfer Mode
* Packet switched systems such as Ethernet or IP

In programming, asynchronous events are those occurring independently of the main program flow. Asynchronous actions are actions executed in a non-blocking scheme, allowing the main program flow to continue processing. [http://msdn2.microsoft.com/en-us/library/7ch3stsw.aspx Microsoft documentation describing "asynchronous message processing". Accessed on 09-09-2007.]
* Asynchronous I/O
* Asynchronous application programming interfaces (APIs)
* Asynchronous Method Dispatch (AMD)
* Ajax, asynchronous JavaScript and XML

ee also

*Synchronicity (disambiguation)
*Plesiochronous or "almost synchronous" systems
*Isochronous versus anisochronous

External references