i was upgrading a friend’s iMac G3* to Mac OS X 10.3.9 today. after we rebooted, he was stuck in open firmware. after i typed
mac-boot at the prompt, it said default catch and refused to proceed any further.
the usual trick of
did not help.
what did fix the problem was booting off the mac os x installer CD, selecting his hard drive in the startup disk application and restarting the machine.
* with a 20 GB hard drive, partitioned in to 8 and 12 GB partitions, as required.