Real-Time Computing System

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A Real-Time Computing (RTC) System is a Computing System that can solve a real-time task within a specified deadline.



  • (Wikipedia, 2015) ⇒ Retrieved:2015-5-20.
    • In computer science, real-time computing (RTC), or reactive computing describes hardware and software systems subject to a "real-time constraint", for example operational deadlines from event to system response. Real-time programs must guarantee response within specified time constraints, often referred to as "deadlines".[1] Real-time responses are often understood to be in the order of milliseconds, and sometimes microseconds. A system not specified as operating in real time cannot usually guarantee a response within any timeframe, although actual or expected response times may be given.

      A real-time system has been described as one which "controls an environment by receiving data, processing them, and returning the results sufficiently quickly to affect the environment at that time." The term "real-time" is also used in simulation to mean that the simulation's clock runs at the same speed as a real clock, and in process control and enterprise systems to mean "without significant delay". Real-time software may use one or more of the following: synchronous programming languages, real-time operating systems, and real-time networks, each of which provide essential frameworks on which to build a real-time software application. Systems used for many mission critical applications must be real-time, such as for control of fly-by-wire aircraft, or anti-lock brakes on a vehicle, which must produce maximum deceleration but intermittently stop braking to prevent skidding. Real-time processing fails if not completed within a specified deadline relative to an event; deadlines must always be met, regardless of system load.


A real-time operating system that is able to handle hard real-time tasks is called a hard real-time system. Typically, real-world applications include hard, firm, and soft activities; therefore a hard real-time system should be designed to handle all such task categories using different strategies. In general, when an application consists of a hybrid task set, all hard tasks should be guaranteed off line, firm tasks should be guaranteed on line, aborting them if their deadline cannot be met, and soft tasks should be handled to minimize their average response time.


  • (Wiktionary, 2009a) ⇒
    • 1. (computing) of a system that responds to events or signals within a predictable time after their occurrence; specifically the response time must be within the maximum allowed.


  • (Wikipedia, 2009) ⇒
    • In computer science, real-time computing (RTC) is the study of hardware and software systems that are subject to a "real-time constraint" — i.e., operational deadlines from event to system response. By contrast, a non-real-time system is one for which there is no deadline, even if fast response or high performance is desired or preferred. The needs of real-time software are often addressed in the context of real-time operating systems, and synchronous programming languages, which provide frameworks on which to build real-time application software.
    • A real time system may be one where its application can be considered (within context) to be mission critical. The anti-lock brakes on a car are a simple example of a real-time computing system — the real-time constraint in this system is the short time in which the brakes must be released to prevent the wheel from locking. Real-time computations can be said to have failed if they are not completed before their deadline, where their deadline is relative to an event. A real-time deadline must be met, regardless of system load.


  1. Ben-Ari, M., "Principles of Concurrent and Distributed Programming", Prentice Hall, 1990. ISBN 0-13-711821-X. Ch16, Page 164