So, I connected the first 8 ALU boards to implement a 8-bit ALU and tested it. The Shift Left/Right, AND, OR and NOT commands worked perfect. And in the following two pictures you see the calculation of 0x7F + 0x21 = 0xA0 (or: 127 + 33 = 160).

The first picture shows 0x7F + 0x20 = 0x9F (1001 1111, you see the red LEDs).

The second picture shows you 0x7F + 0x21 = 0xA0 (1010 0000).

How fast the calculation realy is will be shown in a video, I plan to finish the 16 bit ALU and measure (and documend) the calculation speed of the 16 bit ALU. I need the calculation time to be able to choose a clock timing for clock 1 of the relay system.