Floppy Disk Legacy
The Power Mac G4 computer has no built-in floppy disk drive, so the existing
.Sony
driver has been disabled using the same techniques as in the iMac software. MFM floppy disks can be supported by a USB-based LS-120 disk drive developed by a third party.
ADB Legacy
The Power Mac G4 computer has no ADB ports. The ADB Manager, however, is still present to retain compatibility with programs that require it.
The system software has an ADB shim layer to allow USB keyboards and mice to appear as legacy ADB devices.
SCSI Legacy
Although there is no SCSI connector on the Power Mac G4 computer, the high-level SCSI interfaces remains in the system. That allows for possible support for SCSI devices using a USB-to-SCSI adapter. Such an adapter would take the USB commands coming from the USB port and convert them into SCSI commands to send to the drive. A SCSI driver would also need to be written that would take the SCSI commands coming from the system and embed them in USB commands that would be sent to the device through the adapter.