3.1 Logical Names
Disks: sd - SCSI controllers, can control 2 disks.
xy - Xylogics 450/451 SMD controller, can control 2 disks.
xd - Xylogics 7053 controller, can control 4 disks.
Tapes: st - SCSI controller: 1/4" QIC, 8mm, 4mm DAT
xt - 1/2" high density Xylogics 472 controller
mt - 1/2" low density Tapemaster controller, and others (sometimes linked to st)
CD-ROM: sr - SCSI controller
where SCSI stands for Small Computer System Interface.