The new CC-PBRL structure brings a new surprise. It now looks like this:

Now we have 8 relays driven by a 12V potential, instead of only 4 relays as in the previous version (shown at the bottom of My first Pre-Biased Relay Logic gates).

This is 2× more efficient but the currents and usage ratio must be taken into account. The previous circuit used a small bias current of 10mA, increasing to 60mA when active.

Now the new circuit has a constant current of 40mA per relays but there are more in series for the same voltage. This is equivalent to 20mA and now it looks more interesting for the high-fanout control signals. There is no reason to make the system more complex with "selective driving" of the large MUX of the register file. The layout and wiring are simple again.

Other advantages : the average current is much more stable (less regulation problems) a bit like the ECL. The load on the -12V/0V domain is constant (and very easy to estimate), the current spikes are mostly felt on the +12V/0V domain which draws much less current.

By the way, instead of having a symmetrical power supply, I'll use one high-power 12V PSU along with a lower-power 24V PSU.

The other advantage is nice too : there are fewer parts, only a capacitor is needed. The previous circuit was wasting power in the bias resistors.