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    <title>Superpositioned: Are you logical? (Digital logic puzzlers)</title>
    <link>http://superpositioned.com/articles/2006/05/17/are-you-logical-digital-logic-puzzlers</link>
    <language>en-us</language>
    <ttl>40</ttl>
    <description>Electronics news and projects in the frequency domain</description>
    <item>
      <title>Are you logical? (Digital logic puzzlers)</title>
      <description>&lt;p&gt;Clive Maxfield recently posed the &lt;a href="http://www.eetimes.com/showArticle.jhtml;?articleID=187002658"&gt;Black Box Brain Boggler&lt;/a&gt; in the Logically Speaking column of May&amp;#8217;s EE Times.  The original article was incorrect and posed an overly simple problem.  In fact, the real problem is much more difficult, but possible none the less.&lt;/p&gt;

&lt;blockquote&gt;
    &lt;p&gt;At first, this appears to be deceptively simple. We start with a black box with three inputs&amp;#8211;A, B and C&amp;#8211;and three outputs (see below). The outputs, which we may name !A, !B and !C, are the logical inversions of the inputs.&lt;/p&gt;
&lt;/blockquote&gt;

&lt;p&gt;&lt;img src="http://superpositioned.com/files/blackbox.gif" alt="Blackbox Diagram"/&gt;&lt;/p&gt;

&lt;p&gt;The challenge is implementing this black box with only two inverters, a bucket of basic gates, and without a hard coded binary 0 or 1.  The bucket of gates presents two levels of difficulty.  The former being far easier than the latter.  In fact, the first bucket should be easy for &lt;em&gt;any&lt;/em&gt; digital design student to solve.&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;&lt;p&gt;The bucket of basic gates contains AND, OR, and XOR gates.  Remember, you cannot connect any of the inputs directly to a binary 0 or 1.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;The bucket contains only AND and OR gates.  The solutions are extremely complex, but do exist!&lt;/p&gt;&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;He recently posted the clarifications and some purposed solutions on DesignLine.  If you are curious, here are the spoilers for challenge &lt;a href="http://superpositioned.com/pages/spoiler1"&gt;one&lt;/a&gt; and &lt;a href="http://www.mobilehandsetdesignline.com/GLOBAL/electronics/designline/shared/article/showArticle.jhtml;?articleId=187203077&amp;amp;pgno=2"&gt;two&lt;/a&gt;.  If you enjoy proofs, there are some more &lt;a href="http://www.eetimes.com/showArticle.jhtml;?articleID=187002658&amp;amp;pgno=2"&gt;logic puzzlers&lt;/a&gt; for your unsatisfied brain.&lt;/p&gt;</description>
      <pubDate>Wed, 17 May 2006 12:16:00 -0700</pubDate>
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      <author>Matthew</author>
      <link>http://superpositioned.com/articles/2006/05/17/are-you-logical-digital-logic-puzzlers</link>
      <category>Challenges</category>
      <category>logic</category>
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    <item>
      <title>"Are you logical? (Digital logic puzzlers)" by Lian</title>
      <description>&lt;p&gt;I please to know you I am studing Electronic Engineeringhave and i have&lt;br /&gt;
 interested It and i would like to know a detial &lt;/p&gt;</description>
      <pubDate>Wed, 05 Jul 2006 22:48:45 -0700</pubDate>
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      <link>http://superpositioned.com/articles/2006/05/17/are-you-logical-digital-logic-puzzlers#comment-171</link>
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