The complete system was simulated using the very good software "Logic World". A very simple relay was designed, this relay (and a diode) was used to build the complete design. The following picture set shows an overview about the simulation and a detailed picture of the 16 bit ALU:
The first step of the realization of the system was to test the realys, check out if the circuits will work in reality as good as they worked in the simulation. For this tests some test boards and an oscilloscope where used to find out the timing parameters of the relays:
The results of the tests where amazing...the slowest relays where closed or opened in 7,5 ms. Thats not bad for a mechanical switch.
The realization of the system startet with the 16 bit instruction register. Now the control unit is running 5 NOP command per second.