Instead of building an entire computer in one go, I decided to create it as separate modules. This ALU is the first component I’ve completed toward that goal.

Its total size is 6.1 × 6.1 × 6.5 cm (approximately 2.4 × 2.4 × 2.56 inches) and consists of five stacked PCBs. Four identical boards handle 4 bits each, while a top board contains 56 LEDs.

It is fully compatible with the NAND2Tetris ALU but lacks a dedicated NG output pin, which indicates a negative output value. However, if the output is negative, the highest bit will always be high, so you can use that instead. Additionally, it includes a Carry (C) output pin, which the original lacks, and this may prove useful further down the line.