180:. Serial programs operate on the incoming data characters or packets sequentially, one at a time. In some of these programs, information about previous data characters or packets received is stored in variables and used to affect the processing of the current character or packet. This is called a
276:. To change the channel of a TV, the user usually presses a channel up or channel down button on the remote control, which sends a coded message to the set. In order to calculate the new channel that the user desires, the digital tuner in the television must have stored in it the number of the
54:. The system's internal behaviour or interaction with its environment consists of separately occurring individual actions or events, such as accepting input or producing output, that may or may not cause the system to change its state. Examples of such systems are
206:) that describes computation in terms of the program state, and of the statements which change the program state. Changes of state are implicit, managed by the program runtime, so that a subroutine has
104:, whose outputs are a function of both the current inputs and the past history of inputs. In sequential logic, information from past inputs is stored in electronic memory elements, such as
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it is on. It then adds one or subtracts one from this number to get the number for the new channel, and adjusts the TV to receive that channel. This new number is then stored as the
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memory element has only two possible states, 0 or 1, the total number of different states a circuit can assume is finite, and fixed by the number of memory elements. If there are
300:, which preserves the information when the TV is turned off, so when it is turned on again the TV will return to its previous station and volume level.
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produced by the speaker. Pressing the volume up or volume down buttons increments or decrements this number, setting a new level of volume. Both the
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The output of a sequential circuit or computer program at any time is completely determined by its current inputs and current state. Since each
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binary memory elements, a digital circuit can have at most 2 distinct states. The concept of state is formalized in an abstract mathematical
188:. In others, the program has no information about the previous data stream and starts fresh with each data input; this is called a
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331:, so it can be restored when the computer comes out of hibernation, and the processor can take up operations where it left off.
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as explicit variables that represent the program state at each step of a program execution: a state variable is passed as an
127:, and there is a finite number of memory elements, a digital circuit has only a certain finite number of possible states. If
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A more specialized definition of state is used for computer programs that operate serially or sequentially on
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if it is designed to remember preceding events or user interactions; the remembered information is called the
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is the number of binary memory elements in the circuit, the maximum number of states a circuit can have is
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languages, the program describes the desired results and doesn't specify changes to the state directly.
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to save energy by shutting down the processor, the state of the processor is stored on the computer's
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subroutine only has visibility of changes of state represented by the state variables in its scope.
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and the data carried over from the previous processing cycle is called the
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at any time is completely determined by its current inputs and its state.
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of the changes of state made by other parts of the program, known as
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Computer Science, Engineering and Technology
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numbers are part of the TV's state. They are stored in
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An example of an everyday device that has a state is a
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is the contents of all the memory elements in it: the
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The set of states a system can occupy is known as its
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are dependent only on its present input signals, and
360:"What is stateless? - Definition from WhatIs.com"
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437:. Prentice-Hall of India Pvt. Ltd. p. 326.
434:8085 Microprocessor: Programming and Interfacing
410:. UK: Cambridge University Press. p. 735.
377:Harris, David Money; Harris, Sarah L. (2007).
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145:Similarly, a computer program stores data in
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