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Orders of magnitude (data)

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An order of magnitude is a factor of ten. A quantity growing by four orders of magnitude implies it has grown by a factor of 10,000 or 104.

This article presents a list of multiples, sorted by orders of magnitude, for digital information storage measured in bits. This article assumes a descriptive attitude towards terminology, reflecting general usage. The article assumes the following:

  • For the purpose of this article, a group of eight bits may constitute one byte, a group of four bits is assumed to be one nibble. Historically, both assumptions have not always been true.
  • The byte is the most common unit of measurement of information (kilobyte, kibibyte, megabyte, mebibyte, gigabyte, gibibyte, terabyte, tebibyte, etc.).
  • In 16-bit and 32-bit architectures, having processor registers of these sizes, that chunk of data is usually called a word.
  • The decimal SI prefixes kilo, mega, giga, tera, etc., are powers of 10. The binary prefixes kibi, mebi, gibi, tebi, etc. respectively refer to similar multiples.

    • Accordingly:

  • 1 kB (kilobyte) = 103 bytes = 1,000 bytes = 8,000 bits
  • 1 KiB (kibibyte) = 210 bytes = 1,024 bytes = 8,192 bits

    • Note: this page mixes between two kinds of entropies:

    1. Entropy (information theory), such as the amount of information that can be stored in DNA
    2. Entropy (thermodynamics), such as entropy increase of 1 mole of water

    These two definitions are not entirely equivalent, see Entropy in thermodynamics and information theory.

    For comparison, the Avogadro constant is 7023602214179000000♠6.02214179(3)×1023 entities per mole, based upon the number of atoms in 12 grams of carbon-12 isotope.

    In 2012, some hard disks used ~984,573 atoms to store each bit. In January 2012, IBM researchers announced they compressed 1 bit in 12 atoms using antiferromagnetism and a scanning tunneling microscope with iron and copper atoms. This could mean a practical jump from a 1 TB disk to a 100 TB disk.

    References

    Orders of magnitude (data) Wikipedia
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