re:
....
> Diagnostic [on|off] Enable/disable diagnostic boot mode
....
> Does anyone know about "diagnostic boot?

Through trial and error, I have an answer, which I'll post so it'll be
in the archives

On the SAIC Galaxy 1100 (which appears to be a 9000/712 in diguise),
"diagnostic on" seems change the bootup from having just the HP graphic
on display most of the time (until CDE shows up) to having the older style
multiple-line ASCII output displayed. "diagnostic off" reverts to the
quiet, graphic only display.

With "diagnostic off", the graphc display has a line saying something like:
press
<control> <delete> toggle window slate
<control> <insert> toggle boot messages

The former seems to turn the graphcs display on/off (when off, the ASCII
bootup sequence is seen), and the latter enables display of the ASCII bootup
progress messages *in addition to* the graphic (which makes them hard to
read). (No, you can't have no graphic *and* no boot messages