SCSI forwards/backwards compatibility

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markcola
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Joined: May 8 1999

To what extent are various types of SCSI drive (UW SCSI etc) compatible with interfaces of a different type, and vice versa. For example, aside from the number of pins on the connectors (which can be corrected), is a Fast SCSI interface compatible with a SCSI3 drive?

Dave
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Joined: Apr 8 1999

Some of the below might be slightly wrong but not too far I hope.

SCSI is confusing because of the way it is described. Split it into 2 halves, hardware and software.

The software side (protocols) are numbered ie SCSI 1, SCSI 2, SCSI 3. In theary it does not matter what number of pins they, SSA and FCAL use SCSI 3 protocols (well nearly) on twisted pair wires or fibre optic.

Wide, fast, ultra wide and so on is more down to cables and other hardware.

So then on the subject of mix an match try not to. It only ends in tears. The problem most likely to occur is termination problems when cables change to different widths.

If you have a card or motherboard with 2 busses try to keep the devices seperate that way.

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