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<title>Clock</title>
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<h1><img  align="center" src="../../../../en/icons/clock.gif" width="32" height="32">
<em>Clock</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>2.0 Beta 13 (in Base library, moved to Wiring in 2.7.0)</td></tr>
<tr><td valign="top"><strong>Appearance:</strong></td>
	<td valign="top"><img src="../../../../en/img-libs/clock.png" width="23" height="23"></td></tr>
</table></p>

<h2>Behavior</h2>

<p>The clock toggles its output value on a regular schedule as long as
ticks are enabled via the
<a href="../../guide/menu/simulate.html">Simulate menu</a>.
(Ticks are disabled by default.)
A "tick" is Logisim's unit of time; the speed at which ticks occur can
be selected from the Simulate menu's Tick Frequency submenu.</p>
The clock's cycle can be configured using
its High Duration and Low Duration attributes.</p>

<p>Note that Logisim's simulation of clocks is quite unrealistic: In
real circuits, multiple clocks will drift from one another and will
never move in lockstep. But in Logisim, all clocks experience ticks at
the same rate.</p>

<h2>Pins</h2>

<p>A clock has only one pin, an output with a bit width of 1, whose
value will represent the current value of the clock. The location of
this pin is specified in the Facing attribute. The clock's value
will toggle on its schedule whenever ticks are enabled, and it will
toggle whenever it is clicked using the <a href="poke.html">Poke
Tool</a>.</p>

<h2>Attributes</h2>

<p>When the component is selected or being added,
the arrow keys alter its <q>Facing</q> attribute.</p>

<dl>

<dt>Facing</dt>
<dd>The side of the component where its output pin should be.</dd>

<dt>High Duration</dt>
<dd>The length of time within each cycle that the clock's output should
be 1.</dd>

<dt>Low Duration</dt>
<dd>The length of time within each cycle that the clock's output should
be 0.</dd>

<dt>Label</dt>
<dd>The text within the label associated with the clock component.</dd>

<dt>Label Location</dt>
<dd>The location of the label relative to the component.</dd>

<dt>Label Font</dt>
<dd>The font with which to render the label.</dd>

</dl>

<h2>Poke Tool Behavior</h2>

<p>Clicking a clock component will toggle its current output value
immediately.</p>

<h2>Text Tool Behavior</h2>

<p>Allows the label associated with the component to be edited.</p>

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

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