Aiken code

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Aiken code
Digits4[1][2]
Tracks4[1][2]
Digit values2 4 2 1[1][2]
Weight(s)0..4[1][2]
Continuityno
Cyclicno[1][2]
Minimum distance1[1][2]
Maximum distance4[1][2]
Redundancy0.7
Lexicographyyes[1][2]
Complement9[1][2]
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The Aiken code (also known as 2421 code)[1][2] is a complementary binary-coded decimal (BCD) code. A group of four bits is assigned to the decimal digits from 0 to 9 according to the following table. The code was developed by Howard Hathaway Aiken and is still used today in digital clocks, pocket calculators and similar devices.

The Aiken code differs from the standard 8421 BCD code in that the Aiken code does not weight the fourth digit as 8 as with the standard BCD code but with 2.

Aiken code (symmetry property)
Aiken code in hexadecimal coding

The following weighting is obtained for the Aiken code: 2-4-2-1.

One might think that double codes are possible for a number, for example 1011 and 0101 could represent 5. However, here one makes sure that the digits 0 to 4 are mirror image complementary to the numbers 5 to 9.

Aiken code
Decimal
digit 		Aiken
2 4 2 1
code[1][2]
0 0 0 0 0
1 0 0 0 1
2 0 0 1 0
3 0 0 1 1
4 0 1 0 0
5 1 0 1 1
6 1 1 0 0
7 1 1 0 1
8 1 1 1 0
9 1 1 1 1

See also[]

References[]

  1. ^ a b c d e f g h i j k Steinbuch, Karl W., ed. (1962). Taschenbuch der Nachrichtenverarbeitung [Handbook for Signal Processing] (in German) (1 ed.). Berlin / Göttingen / New York: Springer-Verlag OHG. pp. 71–74. LCCN 62-14511.
  2. ^ a b c d e f g h i j k Steinbuch, Karl W.; Weber, Wolfgang; Heinemann, Traute, eds. (1974) [1967]. Struktur und Programmierung von EDV-Systemen [Handbook for Information Systems - Volume II - Structure and programming of computer systems]. Taschenbuch der Informatik – Band II (in German). Vol. II (3 ed.). Berlin, Germany: Springer Verlag. pp. 98–100. ISBN 3-540-06241-6. LCCN 73-80607.

Further reading[]

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