Re: Not16 failure in building the ALU

Posted by cadet1620 on Nov 18, 2012; 5:19pm
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Not16-failure-in-building-the-ALU-tp4025519p4025635.html

This is really bizarre. Working with my ALU.hdl in an otherwise empty subdirectory (no need for the test script):

  o  The "eval" button is properly enabled using the complete HDL file.
  o  Commenting out the connections to all three outputs -- out, zr and ng -- causes the eval button to be permanently disabled.
  o  Commenting out one or two of the output connections does not cause the failure.
  o  Commenting out the connections to out and ng and leaving an internal wire disconnected from its intended input causes the failure.
  o  Commenting out other combinations of two outputs and leaving an internal wire disconnected from its intended input does not cause the failure.

If this is happening to you, I'd suggest checking that all chip outputs are connected to a part output and that all your internal pins/wires are connected on both ends.

--Mark