- Bi-quinary coded decimal
**Bi-quinary coded decimal**is a numeral encoding scheme used in manyabacus es and in some early computers, including the Colossus. The term**"bi-quinary**" indicates that the code comprises both a two-state ("bi") and a five-state ("quin"ary) component. The encoding resembles that used by many abaci, one bead indicating 0..4 or 5..9 and 4 beads indicating which of those ranges.**Decoding**To decode the Biquinary code use the number

**5043210**.At each digit multiply the biquinary number by the number 5043210. This will give you the decimal number.

For example take the number 0110000.To change this into Decimal: (5 * 0) + (0 * 1) + (4 * 1) + (3 * 0) + (2 * 0) + (1 * 0) + (0 * 0) = 4

**Examples**Several different representations of bi-quinary coded decimal have been used by different machines. The two-state component is encoded as one or two

bit s, and the five-state component is encoded using three to five bits. 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); in the picture of the front panel below, the bi-quinary encoding of the internal workings of the machine are evident in the arrangement of the lights – the 'bi' bits form the top of a T for each digit, and the 'quinary' bits form the vertical stem (the machine was running when the photograph was taken and the active bits are just discernible)*Univac LARC – 4 bits (one ‘bi’ bit: 5 and three

ring counter coded ‘quinary’ bits) with 1 parity check bit**See also***

chisanbop

*Binary

*Binary-coded decimal

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