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<title>Transistor</title>
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<h1><img  align="center" src="../../../../en/icons/trans0.gif" width="32" height="32">
<img  align="center" src="../../../../en/icons/trans1.gif" width="32" height="32">
<em>Transistor</em></h1>

<p><table>
<tr><td><strong>Library:</strong></td>
	<td><a href="index.html">Wiring</a></td></tr>
<tr><td><strong>Introduced:</strong></td>
	<td>2.7.0</td></tr>
<tr><td valign="top"><strong>Appearance:</strong></td>
	<td valign="top"><img src="../../../../en/img-libs/trans0.png" width="44" height="23">
	<img src="../../../../en/img-libs/trans1.png" width="44" height="23"></td></tr>
</table></p>

<h2>Behavior</h2>

<p>A transistor has two inputs, called <em>gate</em> and <em>source</em>,
and one output, called <em>drain</em>. When diagrammed, the <em>source</em>
input and <em>drain</em> output are drawn connected by a plate;
Logisim draws an arrowhead to indicate the direction of flow from input to output.
The <em>gate</em> input is drawn connected to a plate that is parallel to the
plate connecting <em>source</em> to <em>drain</em>. Logisim supports two types of
transistors, with slightly different behaviors described below; the P-type
transistor is indicated by a circle connecting the <em>gate</em> input to its
plate, while the N-type transistor has no such circle.</p>

<p>Depending on the value found at <em>gate</em>,
the value at <em>source</em> may be transmitted to
<em>drain</em>; or there may be no connection from <em>source</em>,
so <em>drain</em> is left floating. The determination of transmitting or disconnecting
depends on the type of transistor: A P-type transistor
(indicated by a circle on the <em>gate</em> line) transmits
when <em>gate</em> is 0, while an N-type transistor (which has no such circle)
transmits when <em>gate</em> is 1. The behavior is summarized by the
following tables.</p>

<center><table>
<tr><td><table><thead>
<tr><td></td><th colspan="4" align="center"><b>P-type</b></th></tr>
<tr><td></td><td colspan="4" align="center"><img src="../../../../en/img-libs/trans0.png" width="44" height="23"></td></tr>
</thead><tbody>
<tr><td colspan="2"></td><th colspan="3"><em>gate</em></th></tr>
<tr><td colspan="2"></td><th align="center">0</th><th align="center">1</th><th align="center">X/Z</th></tr>
<tr><td></td><th align="center">0</th>
      <td align="center">0</td><td align="center">Z</td><td align="center">X</td></tr>
<tr><th><em>source</em></th><th align="center">1</th>
      <td align="center">1</td><td align="center">Z</td><td align="center">X</td></tr>
<tr><td></td><th align="center">Z</th>
      <td align="center">Z</td><td align="center">Z</td><td align="center">Z</td></tr>
<tr><td></td><th align="center">X</th>
      <td align="center">X</td><td align="center">Z</td><td align="center">X</td></tr>
</tbody></table></td><td>&nbsp;&nbsp;&nbsp;</td><td><table><thead>
<tr><td></td><th colspan="4" align="center"><b>N-type</b></th></tr>
<tr><td></td><td colspan="4" align="center"><img src="../../../../en/img-libs/trans1.png" width="44" height="23"></td></tr>
</thead><tbody>
<tr><td colspan="2"></td><th colspan="3"><em>gate</em></th></tr>
<tr><td colspan="2"></td><th align="center">0</th><th align="center">1</th><th align="center">X/Z</th></tr>
<tr><td></td><th align="center">0</th>
      <td align="center">Z</td><td align="center">0</td><td align="center">X</td></tr>
<tr><th><em>source</em></th><th align="center">1</th>
      <td align="center">Z</td><td align="center">1</td><td align="center">X</td></tr>
<tr><td></td><th align="center">Z</th>
      <td align="center">Z</td><td align="center">Z</td><td align="center">Z</td></tr>
<tr><td></td><th align="center">X</th>
      <td align="center">Z</td><td align="center">X</td><td align="center">X</td></tr>
</table></td></tr></table></center>

<p>Or in summarized form:</p>

<center><table>
<tr><td><table><thead>
<tr><th colspan="2" align="center"><b>P-type</b></th></tr>
<tr><td colspan="2" align="center"><img src="../../../../en/img-libs/trans0.png" width="44" height="23"></td></tr>
</thead><tbody>
<tr><th><em>gate</em></th><th><em>drain</em></th></tr>
<tr><td align="center">0</td><td align="center"><em>source</em></td></tr>
<tr><td align="center">1</td><td align="center">Z</td></tr>
<tr><td align="center">X/Z</td><td align="center">X*</td></tr>
</tbody></table></td><td>&nbsp;&nbsp;&nbsp;</td><td><table><thead>
<tr><th colspan="2" align="center"><b>N-type</b></th></tr>
<tr><td colspan="2" align="center"><img src="../../../../en/img-libs/trans1.png" width="44" height="23"></td></tr>
</thead><tbody>
<tr><th><em>gate</em></th><th><em>drain</em></th></tr>
<tr><td align="center">0</td><td align="center">Z</td></tr>
<tr><td align="center">1</td><td align="center"><em>source</em></td></tr>
<tr><td align="center">X/Z</td><td align="center">X*</td></tr>
</table></td></tr></table>
<p>* <em>If <em>source</em> is Z, <em>drain</em> is Z; otherwise <em>drain</em> is X.</p>
</center>

<p>If the Data Bits attribute is more than 1, the <em>gate</em> input is still
a single bit, but its value is applied simultaneously to each of the
<em>source</em> input's bits.</p> 

<p>An N-type transistor behaves very similarly to a
<a href="../gates/controlled.html">Controlled Buffer</a>. The primary difference
is that a transistor is meant for more basic circuit designs.</p>

<h2>Pins (assuming component faces east, gate line top/left)</h2>

<dl>

<dt>West edge (input, bit width matches Data Bits attribute)</dt>
<dd>The component's <em>source</em> input that will transmit to the output
if triggered by the <em>gate</em> input.</dd>

<dt>North edge (input, bit width 1)</dt>
<dd>The component's <em>gate</em> input. For P-type transistors, the transistor
will transmit if the <em>gate</em> value is 0; for N-type transistors,
this will trigger the transistor if the <em>gate</em> value is 1.</dd>

<dt>East edge (output, bit width matches Data Bits attribute)</dd>
<dd>The component's output, which will match the <em>source</em> input
if indicated by the <em>gate</em> input, or will be floating if the <em>gate</em>
input is the negation of what indicates negation. If <em>gate</em> is floating
or an error value, then the output will be an error value.</dd>

</dl>

<h2>Attributes</h2>

<p>When the component is selected or being added,
Alt-0 through Alt-9 alter its <q>Data Bits</q> attribute
and the arrow keys alter its <q>Facing</q> attribute.</p>

<dl>

<dt>Type</dt>
<dd>Determines whether the transistor is P-type or N-type.</dd>

<dt>Facing</dt>
<dd>The direction of the component (its output relative to its input).</dd>

<dt>Gate Location</dt>
<dd>The location of the gate input.</dd>

<dt>Data Bits</dt>
<dd>The bit width of the component's inputs and outputs.</dd>

</dl>

<h2>Poke Tool Behavior</h2>

<p>None.</p>

<h2>Text Tool Behavior</h2>

<p>None.</p>

<p><a href="../index.html">Back to <em>Library Reference</em></a></p>

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