{"id":298,"date":"2006-12-25T11:48:24","date_gmt":"2006-12-25T19:48:24","guid":{"rendered":"http:\/\/stephan-zielinski.com\/dwa\/?p=298"},"modified":"2009-02-08T21:22:30","modified_gmt":"2009-02-09T05:22:30","slug":"but-gate","status":"publish","type":"post","link":"http:\/\/stephan-zielinski.com\/dwa\/2006\/12\/25\/but-gate\/","title":{"rendered":"BUT gate"},"content":{"rendered":"<p><code>Truth table<br \/>\n-------------<br \/>\nA B | A BUT B<br \/>\n0 0 | 0<br \/>\n0 1 | 0<br \/>\n1 0 | 1 *<br \/>\n1 1 | 1<\/code><\/p>\n<p>(*) Forces B to be equal to 1 by driving the input voltage to HIGH. If the circuitry upstream isn\u2019t capable of reacting appropriately, the behavior of the BUT gate (and thus the design overall) is undefined.<\/p>\n<p><span class=\"frame-outer  alignleft size-full wp-image-296\"><span><span><span><span><img loading=\"lazy\" class=\"alignleft size-full wp-image-296\" src=\"http:\/\/stephan-zielinski.com\/dwa\/wp-content\/uploads\/2008\/12\/butgate.jpg\" alt=\"butgate\" width=\"415\" height=\"276\" srcset=\"http:\/\/stephan-zielinski.com\/dwa\/wp-content\/uploads\/2008\/12\/butgate.jpg 559w, http:\/\/stephan-zielinski.com\/dwa\/wp-content\/uploads\/2008\/12\/butgate-150x99.jpg 150w, http:\/\/stephan-zielinski.com\/dwa\/wp-content\/uploads\/2008\/12\/butgate-300x199.jpg 300w\" sizes=\"(max-width: 559px) 100vw, 559px\" \/><\/span><\/span><\/span><\/span><\/span><\/p>\n<p>(Using the fourth NAND gate ensures the output is a clean high or low, even on a blurry input voltage from A. For some reason, circuits using a large number of BUT gates tend to be inordinately prone to such troubles.)<\/p>\n<p>The BUT gate is frequently used in the implementation of back-propagation neural networks and in the specialized hardware used to develop analyses supporting the USA\u2019s presence in Iraq.<\/p>\n<p style=\"text-align: center;\">\u00a0\u05e9<\/p>\n<p><em>Addendum<\/em>: Phil Gustafson noted that this design latches on any B high event. This is true, but historically, this hasn\u2019t always been of great importance. For instance, during the Cold War, BUT gates often shared A and B lines with one or more electromechanical NYET gates:<\/p>\n<p><span class=\"frame-outer  alignleft size-full wp-image-297\"><span><span><span><span><img loading=\"lazy\" class=\"alignleft size-full wp-image-297\" src=\"http:\/\/stephan-zielinski.com\/dwa\/wp-content\/uploads\/2008\/12\/nyetgatesmaller.jpg\" alt=\"nyetgatesmaller\" width=\"415\" height=\"333\" srcset=\"http:\/\/stephan-zielinski.com\/dwa\/wp-content\/uploads\/2008\/12\/nyetgatesmaller.jpg 559w, http:\/\/stephan-zielinski.com\/dwa\/wp-content\/uploads\/2008\/12\/nyetgatesmaller-150x120.jpg 150w, http:\/\/stephan-zielinski.com\/dwa\/wp-content\/uploads\/2008\/12\/nyetgatesmaller-300x240.jpg 300w\" sizes=\"(max-width: 559px) 100vw, 559px\" \/><\/span><\/span><\/span><\/span><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Truth table &#8212;&#8212;&#8212;&#8212;- A B | A BUT B 0 0 | 0 0 1 | 0 1 0 | 1 * 1 1 | 1 (*) Forces B to be equal to 1 by driving the input voltage to HIGH. If the circuitry upstream isn\u2019t capable of reacting appropriately, the behavior of the BUT [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[9],"tags":[71,72],"_links":{"self":[{"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/posts\/298"}],"collection":[{"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/comments?post=298"}],"version-history":[{"count":7,"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/posts\/298\/revisions"}],"predecessor-version":[{"id":390,"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/posts\/298\/revisions\/390"}],"wp:attachment":[{"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/media?parent=298"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/categories?post=298"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/stephan-zielinski.com\/dwa\/wp-json\/wp\/v2\/tags?post=298"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}