On Fri, 4 Aug 2017, John P. Willis via cctalk wrote:
Does anyone know if there is some physical jumper or OpenBoot parameter required in order to enable multiprocessor support on a SPARCstation 20?
I do not know of such a switch/jumper. Both my SS2 I upgraded to 2-CPU and 2*2 CPU did not require some change to the NVRAM settings or changing a jumper. But there was a FirwarePROM with the CPU-Sets (HyperSPARC). Probably you should try moving not only the CPU but also the EPROM with firmware to check this... Best regards from Germany, Erik.