So to understand, you are using an older PowerBook that has SCSI, not FireWire.
You can boot the PowerBook into SCSI Disk Mode just fine.
When the desktop computer does not have a FireWire card, it mounts the PowerBook just fine.
When the desktop computer does have a FireWire card, it does not mount the PowerBook. Is this correct?
Have you tried the FireWire card in different PCI slots? Have you tried other SCSI devices to make sure that the desktop will mount SOMETHING when the FireWire card is in?
And, just to make sure... Do you have the PowerBook started up in SCSI Disk mode, and plugged in to the desktop, before starting up the desktop? (I've seen cases where people forgot that SCSI had to be plugged in before turning power on because they're so used to USB and FireWire now.)
You can boot the PowerBook into SCSI Disk Mode just fine.
When the desktop computer does not have a FireWire card, it mounts the PowerBook just fine.
When the desktop computer does have a FireWire card, it does not mount the PowerBook. Is this correct?
Have you tried the FireWire card in different PCI slots? Have you tried other SCSI devices to make sure that the desktop will mount SOMETHING when the FireWire card is in?
And, just to make sure... Do you have the PowerBook started up in SCSI Disk mode, and plugged in to the desktop, before starting up the desktop? (I've seen cases where people forgot that SCSI had to be plugged in before turning power on because they're so used to USB and FireWire now.)