Sun Blade 100 and Registered/buffered memory
By default, the Sun Blade 100 comes with 133Mhz Sync ECC CL3 unbuffered Dimms. By setting jumper JP6 (which is next to the memory slots) you can use registered/buffered memory in the Sun Blade 100.
You can mix registered and unregistered memory on the system board and it still appears to work ok.
Sun Blade 100, power management and ECC errors
The Sun Blade 100 workstations have a problem with their power mangement circuitry. If power management is enabled within Solaris (or Linux I guess) you can get uncorrectable ECC memory errors or other random hangs.
To work around this, you can edit /etc/power.conf and edit the autopm line to be
Obviously you can just uninstall the power management packages.
SunSolve has document #47042 on this issue. Also searching for “Sun blade 100 Alert” reveals a few more tidbits about this machine.