Hard drive cable question -

[Tim]

bobgoodwin:
>> Does it matter which forty pin connector plugs into the master and
>> slave drives?
>>
>> I have come to the realization after struggling with some problems
>> that there are a lot more wires in the ribbon cable than there are
>> connector pins.

Gene Heskett:
> Then you have an ata100 or faster cable.  And yes, in many cases, the 
> drives position on the cable is important.  As in scsi systems, the 
> last drive on the cable must assume that its job is to terminate the 
> cable and try, by the termination enabled when is either jumpered as 
> Master, or is in CS mode and the last drive, to absorb the echos from 
> the signal transitions.

I've never heard of IDE using termination (despite understanding why
transmission lines need proper termination).  There are no termination
options on IDE drives, they seem to rely on tolerance (cable length
being severely limited, nominal expected impedances for interfaces,
etc).  Master and slave dates back to when the master drive controlled
the slave drive (the host didn't control both drives).  

> Also, if the cable is a cable select cable, as evidenced by having a 
> black connector on what should be the motherboard and, and 2 other 
> colors are used for the other two connectors, then the drives should be 
> jumpered for CS, and the master drive must be on the far end of the 
> cable.

You do NOT NEED to use cable-select cables *as* cable-select cables,
that's optional.  You *can* do so, you do not *have* to do so.


>> I thought "cable select" cables had wires obviously crossed in the
>> ribbon cable but that may not be true with this 80 wire ribbon?

> Untrue, that is used only rarely even in the scsi world.

I've never seen a SCSI cable with crossed wiring.  Do you have an
example?

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