Discrete 8bit CPU project

This is a highly pointless project, aiming to create an 8bit CPU out of discrete 74xx ICs (mostly discrete logic gates). Of course if we ever make it to a complete CPU, we'll also try to build a simplistic mini-computer using it.

This web site will track the progress of our 8bit CPU project.

All the schematics, PCB designs, documentation, and any software we create for this project will be available as free/open whatever-each-thing-is, on our bitbucket project repository.

Arithmetic & Logic Unit (ALU)

The ALU we're designing is a set of stackable interconnected boards (modules), implementing one or two of the operations each; see the logisim prototype circuit (under the sim/ directory) for a rough overview of how it works.

The bottom board of the stack will connect the ALU to the rest of the CPU, and will handle opcode decoding, in conjunction with enable line selection jumpers on each ALU module. The top board will have a set of LEDs and DIP switches, to test and showcase the functionality of the ALU as a standalone unit.


Progress pictures

Progress pictures in reverse chronological order

progress pic: 3 modules