That's similar to what I was thinking SGIs all have the SCSI host adaptor at SCSI ID 0. Generally, the PROM matches known types to user-identifiable strings (e.g. SCSI Disk: dksc(0,1); SCSI Tape: dksc(0,4)) I know that CD-ROM devices were not included in the PROM, and they appear as "Unknown SCSI type 5 / removable: SCSI (0,6)" [or whatever the address is], which correlates to the decimal conversion of the "Perepheral Device Type" field returned in byte 0 by the inquiry command (CD-ROM=0x5). I'm not sure where 0xBF is coming from- that doesn't look like a valid type. So there must either be a spurious signal (or excessive skew) or a bad host controller. It sounds like the 0xBF is being reported for all types, including a tape drive (should be 0x1), ZIP, and something else that I can't find in an email right now, but I think it was a MO. bear made a suggestion that it might be a problem with the termpwr. Hmm- he says he's already desoldered the 33C93A and put in a socket, so I might just go ahead and scavenge another 33C93A from a board in the garage and send it to him (the PI owner, not bear).