Sun Nvram Madness
A few weeks ago I had to troubleshoot a Sun Ultra-10 system. Oh, the memories of working for a Sun Microsystems reseller and learning how to program in Forth. Anyway, as part of my debugging, I usually turn the diag-switch? to true in the OpenBoot prompt. What I’m saying is, I press Stop+a and at the OpenBoot prompt type:
ok? setenv diag-switch? true
Now for the catch. When you turn the diag-switch? on the output is printed in the serial console. This means the first serial port. If you don’t have a serial console, and you’re using the system with a monitor and keyboard, you’ll find yourself staring at a dark screen for a couple of minutes while the diagnostics run.
It’s really easy to think the machine is busted if you don’t know what’s going on. And that is precisely what happened to me.
Now for the punchline. Apple’s computers also use Open Firmware, the
incantation is Option+Command+o+f. Once you’re in Apple’s
OpenFirmware prompt, you can also turn diag-switch?
on. Guess what
happens… yup, a few minutes staring at a dark screen thinking the
machine had died. Only Apple computers don’t really have a serial
port.