Binary-coded decimal: Difference between revisions

Revision as of 20:59, 18 September 2004

Revision as of 21:00, 18 September 2004

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==BCD in electronics==

BCD is very common in electronic systems where a numeric value is to be displayed, especially in systems consisting solely of [[digital]] [[logic]], and not containing a [[microprocessor]]. By utilising BCD, the manipulation of numerical data for display can be greatly simplified by treating each digit as a separate single sub-circuit. This matches much more closely the physical reality of display hardware - a designer might choose to use a series of separate, but identical [[7-segment display]]s to build a metering circuit, for example. If the numeric quantity were stored and manipulated as pure binary, interfacing to such a display would require complex circuitry. By working throughout with BCD, a much simpler overall system results. bhj

==Higher-density encoding==

If a decimal digit requires four bits, then three decimal digits require 12 bits. However, since 2¹⁰>10³, if three decimal digits are encoded together then only 10 bits are needed. '''Two such encodings are'''

''Chen-Ho encoding'' and ''densely packed decimal''.