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==Simple encoder==
[[File:A Simple 4-2 encoder using or gate.jpg|alt=A simple 4:2 Encoder using OR gate.|thumb|318x318px|A simple 4:2 Encoder using OR gate.]]
A [[simple encoder]] circuit is a [[one-hot]] to binary converter. That is, if there are 2<sup>''n''</sup> input lines, and at most only one of them will ever be high, the binary code of this 'hot' line is produced on the ''n''-bit output lines.
For example, a 4-to-2 simple encoder takes 4 input bits and produces 2 output bits. The illustrated gate level example implements the simple encoder defined by the truth table, but it must be understood that for all the non-explicitly defined input combinations (i.e., inputs containing 0, 2, 3, or 4 high bits) the outputs are treated as don't cares.
[[File:Encoder diagram.svg|thumb|212px|Gate level circuit diagram of a single bit 4-to-2 line encoder]]
{| class="wikitable"
|+ 4 to 2 Simple Encoder
!style="border-bottom:2px solid #000;"|I<sub>3</sub>
!style="border-bottom:2px solid #000;"|I<sub>2</sub>
!style="border-bottom:2px solid #000;"|I<sub>1</sub>
!style="border-bottom:2px solid #000;"|I<sub>0</sub>
!style="border-bottom:2px solid #000; border-left:2px solid #000;"| O<sub>1</sub>
!style="border-bottom:2px solid #000;"|O<sub>0</sub>
!style="border-bottom:2px solid #000;"|V
|-
| 0 || 0 || 0 || 0 ||style="border-left:2px solid #000;"| x || x || 0
|-
| 0 || 0 || 0 || 1 ||style="border-left:2px solid #000;"| 0 || 0 || 1
|-
| 0 || 0 || 1 || 0 ||style="border-left:2px solid #000;"| 0 || 1 || 1
|-
| 0 || 1 || 0 || 0 ||style="border-left:2px solid #000;"| 1 || 0 || 1
|-
| 1 || 0 || 0 || 0 ||style="border-left:2px solid #000;"| 1 || 1 || 1
|}
If the input circuit can guarantee at most a single-active input, a simple encoder is a better choice than a priority encoder, since it requires less logic to implement.
==References==
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