Some basic rules:
* Always have terminators at both ends of your physical bus-cable. No stubs!
Terminator--Device--Device--Device--Device--Terminator
* Check termination on the devices and their ID. Get hold of documentation. Ie NO device in the middle of the bus-cable may have their termination enabled.
* Beware of older devices that doesn't implement termination power with correct polarity. These devices has to have their bus-power disabled!
* Check that "parity enable" is set to the same on all devices. It's usually disabled.
* Controller is usually located at ID=7 but can vary.
* Highest ID have the highest priority. Except for wide-scsi where the priority is 7..0 and then 15..8.
* ID numbers only matters for software. So the numbering doesn't have to follow how the drives are physically attached.
Things that are nice about SCSI is that you can have
many drives and the host interface can query them about just about anything. Sector ordering is consistent such that you can swap drives with friends. The electrical interface is consistent and electrically sound. SCSI drives usually have much higher build quality. Track-reordering makes it faster. It's even possible to let one controller boot from another controller if one wishes to do so
, or have more than one controller use the same disc. On the host side, transfers are usually implemented with DMA and other efficient means etc..
