Re: Eval button keeps being disabled

Posted by cadet1620 on
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Eval-button-keeps-being-disabled-tp4025192p4025194.html

yusufgandhi wrote

In the Hardware Simulator Tutorial PDF file, on page 13 (out of 49), in the section Interactive Chip Testing, we are told to be able to change the value of the input pins.

And when we change the values, the simulator SHOULD respond by:
1) Darkening the output and internal pins,
2) Enabling the eval (calculator-shaped) button.

These two things didn't happen in my Hardware Simulator program. What happened? I included a screen shot from the Hardware Simulator in my computer.

It looks like the instructions in the Hardware Simulator Tutorial are incorrect.

Copy your Xor.hdl into the projects\00 directory and open that copy in the simulator and you should be able to edit and evaluate as described. Make sure that when you click on "PARTS:" all the chips displayed have type BuiltIn.

What's happening is that when you load your Xor.hdl from projects\01 it is trying to use the Not, And and Or parts in the projects\01 directory. Since you haven't done project 1 yet, these parts have no implementation and the Hardware Simulator is silently failing. Note that in your screenshot (and the one in the tutorial) the chip types are Composite.

When you start on project 1, it is very important that you implement and test the chips in the order listed in 1.3 to prevent this sort of problem.

--Mark