I built my first computer, with a Z80-CPU by myself. I started with a memory of 1KByte and expanded this computer later up to 4KByte. My own small operating-system was stored in an EPROM. Because of the upgrading ability, I used a special "thread-technique" to connect the integrated circuits with small copper-laquer-wires. A ballpen without the "ball" was my tool for this. After I didn't used this computer anymore, I used most of the ICs in other electronic circuits. In the left long socket was the Z80-CPU and in the upper middle part of the plate one can see the reset button.