A lot of projects ported from the old metanohi site.

site/projects/electruth/truthtables.org

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+#+title: Electruth :: Truth tables
+#&summary
+A guide to using truth tables with electruth
+#&
+#+license: bysa, page
+
+* HOWTO: Truth tables in electruth
+
+The truth table syntax used in electruth is simple: columns are separated by
+commas (but can be separated by tabs instead), and rows are separated by
+newlines. The first row must contain at least one input column and at least one
+output column. To specify that something is input, prefix the input variable
+with a '<' character. To specify an output, use the '>' character. This is best
+illustrated with an example:
+#&pre
+<A,<B,>out
+0,0,1
+0,1,0
+1,0,0
+1,1,1
+#&
+
+If you save this file as something.csv (.csv means it consists of
+comma-separated values) and run `electruth something.csv', you should get an
+output like this:
+
+#&pre
+out = or(and(not(A), not(B)), and(A, B))
+#&
+
+This makes sense, considering that the output variable `out' is only true (a
+"1" in the truth table) when `out' is either not A and not B or A and B.
+
+So, that's how you make a truth table understandable by electruth. I want to
+stress that electruth's output can almost always be shortened. In the example
+above, we can see that `out' is false ("0") when A or B is true -- it is false
+only when A is false and B is true, and when A is true and B is false. This
+construct can be shortened to fit the XOR operator, and we can say that `out'
+is false when out = A XOR B. This means that `out' is true when out = NOT (A
+XOR B) (in the internals of electruth, this would be written as "out =
+not(xor(A, B))"). This is much shorter than "out = or(and(not(A), not(B)),
+and(A, B))". To test if the two expressions really match, electruth can be used
+(and this is really electruth's best part) by running this:
+
+#&pre
+electruth truthtable.csv 'out=not A xor B'
+#&
+
+which should return this:
+
+#&pre
+out_0 = or(and(not(A), not(B)), and(A, B))
+out_1 = or(and(not(A), not(B)), and(A, B))
+ '- out_0 matches out_1? True
+#&
+
+which just confirms that it is true.
+
+
+I created electruth to help me design electronic digital circuits. I don't know
+what you use it for, but if you stumbled upon it because of that, I can
+recommend you take a look at the programs called Ktechlab and Qucs. They can be
+used for boolean logic as well.