I am starting yet another thread about topic's issue becauce, long story short, I fucked up my system (removed the power plug while was on - now HDs aren't recognised). I am startin from scratch and currently am to the point where I just want to boot into MorphOS while HDs are physically removed.
System: PowerMac 3.1 - 4.2.8f1 bootrom
0 > dev usb0 ls
ff969595: /disk@1
ok
^ So, I am assuming that usb disk is correctly recognised on onboard port 0 - given that port 1 lists the keyboard attached (while all other devices are disconnect).
However, I am getting the following error on next prompt:
0 > boot usb0/disk@1:,\boot.img bi umsd0:morphos.iso can't OPEN: usb0.disk@1:,\boot.img
^ I have checked with 2 different sticks (32GB and ~600MB something). Procedure was done on Win11 system and extracted boot.img was taken from macppc_32 folder (not 64 which corresponds to G5) - from latest public MorphOS release.
Any idea what could be going wrong? What's the command to boot from CD? (holding "c" doesn't work).

dev usb0:,\ dir
or so should also work if OF can read it (not sure what the exact sytax is, sorry)

Syntax of bootcommand is OK.
Try dir usb0/disk@1:,\
Does that list the content of the USB-stick? If not, your stick can't be read. It *must* be formatted in old FAT (not FAT32 a.s.o.)

If it shows content, check boot.img! Is it the propper one for your MAC? Sometimes the "blessing", which "chooses" the right boot.img does'nt work with USB.

If there are problems with iso, just copy the content(!) of the iso to the stick. Name the stick "USBSys". Be sure that correct boot.img is copied to root-dir and named boot.img.
Then boot with:
boot usb0/disk@1:,\boot.img BD=USBSys

booting from CD: boot cd

Question: If you plug in USB an power-on after, can you see the ud-devicealias (>devalias)? If, then replace usb0/disk@1 with ud

[ Editiert durch Amigaharry2 02.09.2026 - 16:50 ]