Encyclopedia of Algorithms

2016 Edition
| Editors: Ming-Yang Kao


  • Norbert ZehEmail author
  • Ulrich Meyer
Reference work entry
DOI: https://doi.org/10.1007/978-1-4939-2864-4_190

Years and Authors of Summarized Original Work

  • 1988; Aggarwal, Vitter


The input/output model (I/O model) [ 1] views the computer as consisting of a processor, internal memory (RAM), and external memory (disk). See Fig.  1. The internal memory is of limited size, large enough to hold M data items. The external memory is of conceptually unlimited size and is divided into blocks of B consecutive data items. All computation has to happen on data in internal memory. Data is brought into internal memory and written back to external memory using I/O operations (I/Os), which are performed explicitly by the algorithm. Each such operation reads or writes one block of data from or to external memory. The complexity of an algorithm in this model is the number of I/Os it performs.


Disk access model (DAM) External-memory model 
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Recommended Reading

  1. 1.
    Aggarwal A, Vitter JS (1988) The input/output complexity of sorting and related problems. Commun ACM 31(9):1116–1127MathSciNetCrossRefGoogle Scholar
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    TPIE – a transparent parallel I/O-environment. http://www.madalgo.au.dk/tpie. Accessed 23 June 2014
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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Faculty of Computer ScienceDalhousie UniversityHalifaxCanada
  2. 2.Department of Computer ScienceGoethe University Fankfurt am MainFankfurtGermany