Data stream
Encyclopedia
In telecommunications and computing
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...

, a data stream is a sequence of digitally encoded
Encoder
An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format or code to another, for the purposes of standardization, speed, secrecy, security, or saving space by shrinking size.-Media:...

 coherent
Coherence (physics)
In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....

 signals (packets of data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...

 or data packets) used to transmit
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...

 or receive information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...

 that is in the process of being transmitted.

In electronics
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

 and computer architecture
Computer architecture
In computer science and engineering, computer architecture is the practical art of selecting and interconnecting hardware components to create computers that meet functional, performance and cost goals and the formal modelling of those systems....

, a data flow determines for which time which data item is scheduled to enter or leave which port of a systolic array
Systolic array
In computer architecture, a systolic array is a pipe network arrangement of processing units called cells. It is a specialized form of parallel computing, where cells , compute data and store it independently of each other.thumb|240px...

, a Reconfigurable Data Path Array or similar pipe network, or other processing unit or block (cf. main article).

Often the data stream is seen as the counterpart of an instruction stream, since the von Neumann machine
Von Neumann architecture
The term Von Neumann architecture, aka the Von Neumann model, derives from a computer architecture proposal by the mathematician and early computer scientist John von Neumann and others, dated June 30, 1945, entitled First Draft of a Report on the EDVAC...

 is instruction-stream-driven, whereas its counterpart, the Anti machine, is data stream driven.

The term "data stream" has many more meanings, such as by the definition from the context of systolic array
Systolic array
In computer architecture, a systolic array is a pipe network arrangement of processing units called cells. It is a specialized form of parallel computing, where cells , compute data and store it independently of each other.thumb|240px...

s.

In a formal way, a data stream is any ordered pair
Ordered pair
In mathematics, an ordered pair is a pair of mathematical objects. In the ordered pair , the object a is called the first entry, and the object b the second entry of the pair...

  where:
  1. is a sequence
    Sequence
    In mathematics, a sequence is an ordered list of objects . Like a set, it contains members , and the number of terms is called the length of the sequence. Unlike a set, order matters, and exactly the same elements can appear multiple times at different positions in the sequence...

     of tuple
    Tuple
    In mathematics and computer science, a tuple is an ordered list of elements. In set theory, an n-tuple is a sequence of n elements, where n is a positive integer. There is also one 0-tuple, an empty sequence. An n-tuple is defined inductively using the construction of an ordered pair...

    s and
  2. is a sequence of positive real
    Real number
    In mathematics, a real number is a value that represents a quantity along a continuum, such as -5 , 4/3 , 8.6 , √2 and π...

     time intervals.
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