Problem: You have more than one monitor attached to the system, and the console is not set to the intended monitor.
If you have more than one monitor attached to the system, OpenBoot always assigns the console to the frame buffer specified by the output-device NVRAM parameter. The default value of output-device is screen, which is an alias for one of the frame buffers found by the firmware.
ok nvalias myscreen /sbus/cgsix ok setenv output-device myscreen ok reset-all
ok show sbus-probe-list ( Display the current and default values)
ok setenv sbus-probe-list 2013 ok reset-all
If a non-SBus frame buffer is installed, this second method may not work.