major value	Comment
0..7	Devices on the ACSI bus with ATARI-compatible command set (see Rwabs())
8..15	Devices on the SCSI bus
16..17	Devices connected to the primary IDE interface
17..18	Devices connected to a secondary IDE interface
20..23	Additional IDE devices
24..63	Extensions as defined in the pun field in the PUN_INFO? structure
64	Devices on the standard floppy controller
65..255	Extensions outside the scope of AHDI

The minor device number can range from 0 to 255 max.
For major device number ranging from 0 to 15, the minor device number is the LUN of the ACSI or SCSI device.