<?xml version="1.0" encoding='utf-8'?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml">
<wml>
<card id="card1" title="Interlocking - Page 26 - Wikipedia">
<p>
<a accesskey="1" href="page.php?w=interlocking&amp;p=25">1.Previous</a><br />
<a accesskey="3" href="page.php?w=interlocking&amp;p=27">3.Next</a>
</p>
<p>when needed by reprogramming rather than rewiring. In many implementations, this <a href="page.php?w=safety_critical">vital</a> logic is stored as <a href="page.php?w=firmware">firmware</a> or in <a href="page.php?w=Read-only_memory">ROM</a> that cannot be easily altered to both resist unsafe modification and meet regulatory safety testing requirements. As display technology improved, the hard wired physical devices could be updated with <a href="page.php?w=visual_display_unit">visual display unit</a>s (computer monitors), which allowed changes</p><p>
<a accesskey="1" href="page.php?w=interlocking&amp;p=25">1.Previous</a><br />
<a accesskey="3" href="page.php?w=interlocking&amp;p=27">3.Next</a>
</p>

<do type="prev" label="Search">
        <go href="search.wml"/>
</do>

</card>
</wml>
