Based on an old slashdot article there are still some PDP-11&#x27;s still in use.  
<a href="http:&#x2F;&#x2F;developers.slashdot.org&#x2F;story&#x2F;13&#x2F;06&#x2F;19&#x2F;1227244&#x2F;pdp-11-still-working-in-nuclear-plants---for-37-more-years" rel="nofollow">http:&#x2F;&#x2F;developers.slashdot.org&#x2F;story&#x2F;13&#x2F;06&#x2F;19&#x2F;1227244&#x2F;pdp-11...</a>