I am never comfortable sending out a PCB without simulating first. I decided I had to simulate a few components which I had not. The control chip was one and it's a good thing I did. I found I had a combinational loop that oscillated. Spent a while, but got that fixed without adding more chips.
I also noticed in Ben Eater's videos that he drives a full bank of LEDs without current limiting resistors. I figured I'd just do it. And then the good engineer in me decided I need to double check it. TTL does have an internal pull-up resistor, so it's possible to do it. I measured the draw is 32mA and the datasheet maximum is 24mA. I think I should probably test to failure - it might be at room temperature it can handle more. Or I just put resistors on all 30+ LEDs which takes a lot more board space.
I also discovered some clock glitches while testing. My clock looks like it bounces on the falling edge, and I only caught it when stepping my shift register one clock at a time - it moved twice for every push. I still have the old wired-OR logic hooked up, so I need to put the TTL OR in place to see if that's the problem. More work before ordering PCB...
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