Saturday, August 25, 2012

4-bit ALU - Testing Chips

I have successfully tested 4 out of the 5 chips I need for the ALU. The multiplexor was giving me some trouble; hopefully I can figure out what was going wrong. I've tried several different chips, and I think whatever's going on is because of me, not faulty chips.

Here's a video of that testing in action, on the 4 good chips. While its not overly exciting, I want to document most of this project. So... enjoy?


  1. How do you have the mux hooked up? I pulled up the datasheet and I'm checking it out now.

    1. Hey man, sorry I've been out for a while, I've been moving into school.

      I went into this project not knowing how to switch between a "LOW" and "HIGH" input, so I experimented. 4 out of the 5 IC's I had responded to negative voltage as if it was a LOW signal, and responded to an empty input as a HIGh signal. Thinking this was the way to go, I wired all the inputs to the IC's so that a negative wire was attached to a switch, which was then attached to an input. Someone had told me about pull up and pull down resistors in my first post, but I hadn't used them, and didn't really know what they were. Somebody told me to use them when I asked a question about the mux (ie multiplexor, for the newbies who might eventually read this) on reddit,

      Once I used some resistors on the other end of the switch, it worked beautifully :)