A simple 4-bit CPU and computer, built entirely with 7400 series parts.
Yesterday’s Nibbler celebration was premature – I discovered that about one in ten-thousand writes to RAM stores the wrong value. Bad RAM, bad! No biscuit for you! Arghh, what a headache. I first discovered the problem while making improvements to…
YES, IT WORKS! The Nibbler homemade CPU is up and running, and it can play “guess the number” like nobody’s business. Awesome! If you haven’t seen my earlier posts, Nibbler is a 4 bit CPU built from standard 7400 series logic…
Nibbler construction is underway! I’m building the CPU on a 5 x 4 inch perfboard, and connecting the components using wire wrap. This particular perfboard is a Twin Industries 8200 Series, which has continuous metal planes on both sides that…
I’ve made a few refinements to the Nibbler design, and now I’m ready to start building the CPU! After looking at what seemed like a million different possible changes and additions, I’ve decided to keep the hardware exactly as…
It’s programming time! To verify that Nibbler’s design and instruction set are powerful enough to handle a real program, I sat down to write a simple “guess the number” game. And… (drumroll) it works! I ran the program on…
During development of the Nibbler CPU, I’ve created several software tools to help make my life easier. Some of these have been nearly as interesting as the CPU itself! While professionally I work with C++ or Java, for my personal…
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