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…

Instructions for the Nibbler 4-bit CPU come in two types: immediate and addressed. Both types begin with 4 bits of instruction opcode, to identify the specific instruction. Immediate instructions like ADDI include a 4-bit operand value embedded in the instruction,…

Enough with the vague design talk – here’s the circuit schematic for the Nibbler 4-bit CPU! Click the image to zoom in to a full size view. The whole system fits on a single page, including the CPU itself and…

Say hello to Nibbler, the 4-bit homemade CPU! Ever since I built BMOW1, people have written to me asking how to make their own homebrew computers. BMOW is a complex design that can be difficult to comprehend, so I decided…