A simple 4-bit CPU and computer, built entirely with 7400 series parts.
Vintage Computer Festival West XI is happening next weekend, August 6-7 at the Computer History Museum in Mountain View, California. I’m belatedly dusting off the hardware for my exhibit and preparing the demos and signage. Anybody have a trade show…
William Buchholz has designed and built a PCB version of my Nibbler 4-bit CPU for his local hackerspace. Nibbler is built entirely from standard 7400 series logic chips – individual counters, registers, buffers, and gates. It’s an educational example of…
And here’s why all your circuits should have some kind of reverse-polarity or over-voltage protection: I nearly killed Nibbler yesterday. I brought the hardware to a friend’s house for a nerdfest party, but when I demoed it, I accidentally plugged…
After fiddling with Nibbler’s hardware and fixing its glitches, it’s time to write some demo software. Let’s see what this little handmade 4-bit CPU can do! Sorry the quality on these videos isn’t the best – try changing the quality…
What happens when you feed an invalid voltage level to the input of a digital logic gate? It’s an interesting story. In my last post, I described a subtle Nibbler bug where a combinatorial feedback loop through the ALU caused…
Aha! After four days of tinkering with Nibbler, I finally found the cause of the occasional bad writes to RAM. At first I thought it was a timing problem with the RAM enable signals, then I thought it was bus…
Page 1 of 3
