What the heck is "Cable Select"?

[luisr]

I have had several IDE devices in my system, and all of them have a "Cable Select" jumper. Only the manual for a LS-120 drive I have says it is for a special "Cable select" cable. Yeah right. I love this explanation.

What is this thing?


[Edited by luisr on 02-05-2001 at 04:05 PM]

[zevon8]

Its a cable that normally you plug the middle connector into the mobo and each end goes to a drive. Compaq uses them, and some others. Actually all it is, is a cable with the "CSEL" wire cut before one of the drive connectors. If a drive sees this line as grounded, it becomes "master" , if it is open, it becomes "slave". The wire in question is #28. You can make one if you want, form a noraml cable, just cut wire #28 before the last connector, and that will go to the "slave" drive, the middle connector is "master" and the other end goes to the mobo. I think its done so all drives can be set-up the same at the factory.

[luisr]

That sounds like a good feature, sort of a plug-and-play thing to some extent. Why isn't this used widely?

[Charliey]

Basically, you can set the drives to be master or slave on the drive, but with cable select the master/slave configuration is determined by the order in which the drives are connected to the cable.

it could be useful if you did not want to have to go to the trouble of configuring the master/slave settings. but if you want to have them set to be one way, then it would be more of a hassle to try and get the cable to hook up the right way.

[glc]

ATA66 and ATA100 80 wire cables require the use of cable select. Master or slave is determined by the connector that you use - master is on the black end and slave is in the middle, blue goes on the controller.

[shredmeister]

glc, are you sure about that? I have a Maxtor ATA66/100 capable drive. I used the 80-conductor cable that came with it. In the documentation that came with the drive, it does indeed specify that the blue end goes to the controller, black to the master, and gray to the slave, which is how I set it up (I have no slave device though). However, it mentioned no need for having the drive jumpered to cable select. In fact, they recommended against it saying:

'Most systems do not support this feature. Unless you are sure the system supports cable select, do not set up the drive with this feature enabled.'

It then goes on to say:

'A special IDE cable select interface cable is required for systems using the cable select feature.'

?????

[glc]

That's exactly what that 80 conductor cable is. It is a cable select cable. If you don't have a slave drive, the standard master jumper position will work. If you don't have an ATA66 or ATA100 controller, this becomes a moot point, as then it doesn't matter what kind of cable you use.

[shredmeister]

Thanks for clearing that up. They really don't explain it very well in the docs. It never specifically says to use the 'cable select' jumper setting when using an ATA66/100 cable.