A short beginning...
Juli 13, 2012
Here is the right half of my first full-adder:
front side
Backside of the board:
back side
This version had 2 boards (Two half adders connected). It is 10 cm long and uses THT BC547 NPN transistors with 1k and 10k resistors. Back then I used AND, OR, NOT gates.
The copper paths were made with a thin nail paint.
Part 1 schematic
Part 1 board
Part 2 schematic
Part 1 board