I did a horribly ugly thing and soldered wires to the NMI and ground pins at the CPU, and ran them out to a switch, and used that with Turbo Debugger running on

I did a horribly ugly thing and soldered wires to the NMI and ground pins at the CPU, and ran them out to a switch, and used that with Turbo Debugger running on the second (MDA) monitor. Worked a treat.