Is that possible to change spark to - spark and + spark. - spark can turn things off and + spark turn things on. In the beginning is a button where you can switch +-spark on and off (like heat). Then is possible to create transistors without switch, send 2 type of spark on one line. I know that bay ruin most works but if it can be switced off an on that is not a problem.
This would be an even bigger mess then with PSCN/NSCN. How does the SWCH know if it is the switching command or the signal that is to be switched? You'd end up with a huge pile of undesirables side effects.