The Bi-quinary coded decimal reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Bi-quinary coded decimal

Bi-quinary coded decimal is a numeral system used in some old computers. Bi-quinary means two (bi) and five (quinary) code. In bi-quinary coded decimal, numbers are represented as decimal digits, and each digit is represented a group of bits.

There are several different representations of bi-quinary coded decimal that have been used by different machines, some examples are:

• IBM 650 - 7 bits (two "bi" bits: 0 5 and five "quinary" bits: 0 1 2 3 4) with error checking (exactly one "bi" bit and one "quinary" bit set in a valid digit)
  • + + 05-01234 Bits
  • 0 = 10-10000
  • 1 = 10-01000
  • 2 = 10-00100
  • 3 = 10-00010
  • 4 = 10-00001
  • 5 = 01-10000
  • 6 = 01-01000
  • 7 = 01-00100
  • 8 = 01-00010
  • 9 = 01-00001
• UNIVAC Solid State - 4 bits (one "bi" bit: 5 and three binary coded "quinary" bits: 4 2 1) with 1 parity check bit
  • + + p-5-421 Bits
  • 0 = 1-0-000
  • 1 = 0-0-001
  • 2 = 0-0-010
  • 3 = 1-0-011
  • 4 = 0-0-100
  • 5 = 0-1-000
  • 6 = 1-1-001
  • 7 = 1-1-010
  • 8 = 0-1-011
  • 9 = 1-1-100
• Univac LARC - 4 bits (one "bi" bit: 5 and three ring counter coded "quinary" bits) with 1 parity check bit
  • + + p-5-qqq Bits
  • 0 = 1-0-000
  • 1 = 0-0-001
  • 2 = 1-0-011
  • 3 = 0-0-111
  • 4 = 1-0-110
  • 5 = 0-1-000
  • 6 = 1-1-001
  • 7 = 0-1-011
  • 8 = 1-1-111
  • 9 = 0-1-110

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