<story><title>The ¬NED pin goes low on detection of a nuclear detonation [pdf]</title><url>http://www.maxwell.com/products/microelectronics/docs/HSN1000_REV3.PDF</url></story><parent_chain><item><author>InclinedPlane</author><text>Yeah, GPS doesn&apos;t work so well through the plasma sheath around a reentry vehicle. And you don&apos;t have a whole lot of time to acquire GPS lock, or steer, when you&apos;re still traveling at hypersonic speeds and it takes maybe half a minute to hit the ground after first encountering the upper atmosphere.</text></item><item><author>samfoo</author><text>I&apos;m fairly certain that ICBM&apos;s use inertial guidance with predefined/computed coordinates (&lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_guidance&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Inertial_guidance&lt;/a&gt;). There&apos;s no software involved, its all physical. Detonation is (probably) trigged by a combination of altimeter, accelerometer and other telemetry systems.</text></item><item><author>kabdib</author><text>Think cruise missile. Some code looks at a map, looks at GPS, looks at altitude and velocity, and decides &quot;Yup, this is the spot.&quot;&lt;p&gt;It&apos;s probably a lot more prosaic than I imagine.</text></item><item><author>tdicola</author><text>I doubt the warhead has code to control its activation--more likely it&apos;s something like an altitude sensor that controls detonation.</text></item><item><author>kabdib</author><text>I&apos;ve wondered about the following:&lt;p&gt;The firmware controlling a nuke has to have, at some point, a bit or control register it sets that causes the explosion to go off:&lt;p&gt;&lt;pre&gt;&lt;code&gt;    *pKaboom = true;
&lt;/code&gt;&lt;/pre&gt;
or something like that. My question is: What is the line of code after that?&lt;p&gt;&lt;pre&gt;&lt;code&gt;    *pKaboom = true;
    /*NOTREACHED*/
&lt;/code&gt;&lt;/pre&gt;
I suspect it&apos;s more complicated than that (there&apos;s an infinite loop of some kind that keeps retrying the command sequence). I also suspect I will never know, short of some very hush-hush software being open-sourced someday. :)</text></item></parent_chain><comment><author>sbierwagen</author><text>oelewapperke: I hope you&apos;re reading this, because your reply to this comment is not visible. You&apos;ve been hellbanned.&lt;p&gt;&lt;a href=&quot;http://www.codinghorror.com/blog/2011/06/suspension-ban-or-hellban.html&quot; rel=&quot;nofollow&quot;&gt;http://www.codinghorror.com/blog/2011/06/suspension-ban-or-h...&lt;/a&gt;&lt;p&gt;It happened 175 days ago, when you made an unwise comment about killing children. All your comments since then have not been visible, or upvotable. This is why you&apos;re supposed to put contact information in your profile.&lt;p&gt;I hesitated before posting this, since from your older comments you appear to be a bit of a reddit user, and the comment itself contains several significant technical errors regarding the design of nuclear weapons, (American nuclear weapons haven&apos;t been of the &quot;gun&quot; type for 60 years now) which casts a poor light on the comment as a whole; but I don&apos;t think you&apos;re completely beyond hope.&lt;p&gt;Make a new account. Try not to be an asshole with it.</text></comment>
<story><title>The ¬NED pin goes low on detection of a nuclear detonation [pdf]</title><url>http://www.maxwell.com/products/microelectronics/docs/HSN1000_REV3.PDF</url></story><parent_chain><item><author>InclinedPlane</author><text>Yeah, GPS doesn&apos;t work so well through the plasma sheath around a reentry vehicle. And you don&apos;t have a whole lot of time to acquire GPS lock, or steer, when you&apos;re still traveling at hypersonic speeds and it takes maybe half a minute to hit the ground after first encountering the upper atmosphere.</text></item><item><author>samfoo</author><text>I&apos;m fairly certain that ICBM&apos;s use inertial guidance with predefined/computed coordinates (&lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_guidance&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Inertial_guidance&lt;/a&gt;). There&apos;s no software involved, its all physical. Detonation is (probably) trigged by a combination of altimeter, accelerometer and other telemetry systems.</text></item><item><author>kabdib</author><text>Think cruise missile. Some code looks at a map, looks at GPS, looks at altitude and velocity, and decides &quot;Yup, this is the spot.&quot;&lt;p&gt;It&apos;s probably a lot more prosaic than I imagine.</text></item><item><author>tdicola</author><text>I doubt the warhead has code to control its activation--more likely it&apos;s something like an altitude sensor that controls detonation.</text></item><item><author>kabdib</author><text>I&apos;ve wondered about the following:&lt;p&gt;The firmware controlling a nuke has to have, at some point, a bit or control register it sets that causes the explosion to go off:&lt;p&gt;&lt;pre&gt;&lt;code&gt;    *pKaboom = true;
&lt;/code&gt;&lt;/pre&gt;
or something like that. My question is: What is the line of code after that?&lt;p&gt;&lt;pre&gt;&lt;code&gt;    *pKaboom = true;
    /*NOTREACHED*/
&lt;/code&gt;&lt;/pre&gt;
I suspect it&apos;s more complicated than that (there&apos;s an infinite loop of some kind that keeps retrying the command sequence). I also suspect I will never know, short of some very hush-hush software being open-sourced someday. :)</text></item></parent_chain><comment><author>sp332</author><text>Cruise missiles, on the other hand... Well, let&apos;s just say there are eye-witness accounts of one flying down the street and turning the corner at an intersection before detonating in a tiny radius. All the was left of the target was a single shoe, IIRC.</text></comment>