From ubuntu site netbook page, download mini.iso and burn a CD or DVD.
Select that for powerpc, big-endian, 32-bit.

Insert the CD to the machine and reboot.
Press c after turning the power on to boot from CD.
Insert "cli" to install CLI Ubuntu since most GUI, Window Managers, Desktops do not work.
Some X window managers such as ctwm, dwm are tried. But after some minutes, screen freezes.
Especially Desktops are bothering since they cannot be removed.
Recovery mode during booting cannot be entered. I don't know why.
Just installing LXDE made automatic desktop login and results in crashes.

After installing Ubuntu:

Wifi:
b43 driver problem is solved by "sudo apt install firmware-b43-installer" according to the guide of the site that is found by command "dmesg" showing the linux log.

Sound:
Installed ALSA by "sudo apt install alsa-base alsa-common", but not worked.
Check if modules like b43, snd_aoa_i2sbub, snd_powermac are loaded by "lsmod". Already loaded
Comment out pcspkr module in blacklist.conf and reloaded by "sudo modprobe pcspkr".
Commands like "amixer sset Master 50%" or setting all controls by amixer is not working.
And finally, setting only PCM channel by "amixer set PCM 80" worked.

Video:
X11 needs window managers which results in crashes.
So I tried playing video with framebuffer with mplayer like "mplayer -vo fbdev2 videofile.mp4".
For this, the user has to permission to use /dev/fb0 by adding the user to the group "video" and "audio".
But the playing quality is poor.

Transmission:
Install by "sudo apt install transmission-cli transmission-daemon"
Edit by "sudo vi /var/lib/transmission-daemon/info/settings.json" according to https://help.ubuntu.com/community/TransmissionHowTo
and change "rpc-authentication-required" to false
and change "download-dir" to /home/soh/transmission
and add "watch-dir" as /home/soh/transmission
and add "watch-dir-enabled" as true.
Without this authentication change, transmission-remote is not working.
Put a torrent file in /home/soh/transmission
and start the transmission-daemon by t-start.
By transmission-remote, we can check the status: "transmission-remote -l"
The file is downloaded in /home/soh/transmission
After downloading, stop the daemon by t-stop.
To stop a torrent with ID 2: "transmission-remote -t2 -S"
To remove a torrent with ID 2: "transmission-remote -t2 -r"
To stop all torrents: "transmission-remote -tall -S"

Samba:
According to https://tutorials.ubuntu.com/tutorial/install-and-configure-samba#0
Share /home/soh/transmission
with read/write permission

video card:
Screen freezes a few minutes after x window manager started.
cf. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1571416
In /etc/yaboot.conf, one recommends
append="radeon.agpmode=-1 modprobe.blacklist=ams"
or another recommends
append="radeon.agpmode=-1 radeon.modeset=1 video=offb:off video=radeonfb:off"
I tried the first one and xinit with dwm.
It seems to work.

web browser:
midori is lightweight. About half in memory compared to Firefox 250~300MB.
needs unicode ttf fonts.
firefox is stable. midori is unstable when starting by non-root user.

fonts:
$ sudo apt install ttf-ubuntu-font-family
or
$ sudo apt install ttf-unifont

external monitor:
$ xrandr
shows connected displays. Enable the external monitor, as follows:
$ xrandr --output DVI-0 --auto --same-as LVDS
And then reboot.
Or
Just connect the cable and reboot.

suspend:
It can be done with DPMS.
Maybe after xinit,
$ xset q
shows current settings.
$ xset s 60 60
makes screen saver time to be 1 minute.
$ xset dpms 60 60 60
makes suspend time to be 1 minute.
Without X, maybe setterm can be used.

hibernate:
$ sudo systemctl hibernate
To wake up, press power button.