digging into the port-ppc archives i found several messages about the
state of the mach64 and how many people have problems with it...

as a last resort i decided to try a more bleeding edge version of
netbsd, so i got a daily snapshot of netbsd3 (built on 13/8) and
installed it...

well this time X11 runs, unfortunately i'm not able to see it because
as soon as X starts the monitor goes into standby (and the power
button becames orange), when i kill X the monitor exits standby and
the power button becames again green... :(

at least this is a change to the "(EE) No devices detected." i have
seen so far, the logs shows that the video chipset is recognized
correctly

http://www.webalice.it/chame.leon/snapshot/XFree86.0.log

has anyone seen this behaviour? can be avoided?

leonardo