Seagate ST31250N Product Manual page 59

Barracuda 2LP Product Manual, Rev. D 49
7 & 8* SCSI ID bit 0
9 & 10* SCSI ID bit 1
11 & 12*SCSI ID bit 2
13 & 14 Reserved
15 & 16 Reserved
17 & 18 Reserved
19 & 20 Reserved
*See Figure 19 to set the SCSI ID.