8-Bit Computer

I have decided to build Ben Eater’s 8-bit Computer during Winter break. The initial wiring is done. Of course, that didn’t go without issues.

1. I ran out of wire. That’s my own fault; I changed the layout of the board and made some miscuts. I had other colored wire laying around, but that was not single-core. You’ll see some of the green stuff in the bottom-left (see below). Since it is not solid core, it also doesn’t hold shape as well.

2. I fried a ton of LEDs in the process. So, despite reading Helpful Tips and Recommendations for Ben Eater’s 8-Bit Computer Project and not using current-limiting resistors everywhere, I went ahead and did that.

   This also solved the problem of low voltages, causing inputs not to reach TTL levels.

   LEDs were easy to get on Amazon.

3. I must have also killed some other components along the way. I know of at least one 74LS245 and one 74LS04. Amazon to the rescue again for a set of various components and for a bunch of new inverters.

4. The DIP switches just didn’t want to stay in the board, so I ended up having to solder some header pins to them. That fixed the issue completely.

5. One of my memory chips was bad. Reddit to the rescue. Thanks to The8BitEnthusiast on the r/beneater subreddit, I found an updated schema using a newer memory chip in the r/beneater Subreddit.

Right now, I’m troubleshooting. It seems that the 47LS173 in the instruction register is getting all the correct input voltages, but doesn’t actually output the bus signal to the output pins.

When I remove the chip from the board and test it in isolation, it does work, however.