The early DEC SCSI machines set the host adapter to ID 6, leaving the highest priority ID (7) free. I read something somewhere that suggested that this was insurance just in case something came along that demanded to be the highest priority thing on the bus. Apparently nothing did because the later machines allow the host adapter ID to be set via the console. Typically disks are given lower numbers than tapes, CDROMs seem to sit in the middle. I doubt that it matters in most configurations (it's certainly nowhere near as critical as, say, Qbus priority). Antonio