What model of Seagate is it? There are consistent jumpering needs throughout their range of models, and some needs that are peculiar to Wide as opposed to Narrow, or LVD as opposed to single-ended. Seagate is both clear and consistent in its documentation, but, as a generality for Macs, you need TE for the ultimate drive in the chain, TP from the drive, and can mostly ignore PE or PD, WP, DS, ME and, of course, SS or RES. In Macs you could go a lifetime under SCSI and never use more than TE and TP, in addition to the SCSI ID settings

Other makers (IBM/Hitachi, hp, Fujitsu, Quantum and so on) can have more and differing needs from model to model, but that is not your concern here.

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