PATA - Cable Select

[RJM]

I was just wondering why anyone would use the cable select jumper setting on a PATA hard drive, A

Google search finds that some people use this setting when they are frequently swapping drives.

I can't help thinking that this is just a useless jumper setting, or am I missing something?

[IcemanND]

It just makes it easier to install new drives for the non technically minded person. Don't have to worry about setting the other drie to master/slave etc. Just plug into available cable connection and go.

Not useless but not always useful since the cable has to be a CS cable and both drives on it have to be set that way.

Wish it had been around when you had more options with the jumpers:

Only drive

Master with slave

Slave

Master with incompatible slave

It seems to me there were a few others but that was too long ago.

[LLXX]

It was inherited from the floppy disk subsystem, where a twist in the cable would indicate whether the drive was A/B (or C/D for those few lucky enough to have three/four floppies ) I've always explicitly set Slave and Master on my drives, since setting them both to CS results in them both being detected as master (rubbish shows up in the Master: setting and the Slave: shows nothing).

[Andromeda43]

I see this or a similar question quite often in the forums.

What most folks, even some so-called techs, don't realize is that there are TWO completely different types of PATA drive data cables.

One is just a "Straight Through" cable with one connector for the motherboard and two for the HD's.

A drive jumpered as master can be put on either of the two drive connectors with equal results.

Likewise a second drive jumpered as SLAVE.

Then there's the "Cable Select" cable. It will have a little cut in it somewhere between the two drive connectors making the connector on the End the master connector and the one in the middle the Slave connector.

Any drive connected to this type of cable must be jumpered as "Cable Select".

Before someone starts playing with the jumpers, it helps to know for sure what type of cable they have.

Cables that have the words "Master" and "Slave" printed on them are most likely the cables that require all jumpers to be set to Cable Select.

As far as the usefullness of all this.....well, the jury is still out on that one.

I try to always use the "Straight Through" type of cables whenever possible.

I've thrown away dozens of Master/Slave cables over the years.

Good Luck,

Andromeda43

[EAT MY DUST]

Cable select—The position of the drive on the cable determines which drive is master and which is slave; Cable Select requires an 80-wire Ultra ATA cable. Some computer vendors use specially designed 40-wire cables that support Cable Select. Note that you can also use Master and Slave settings with 80-wire cables.

Color-Coding for Easier Cable Installation

Almost all 80-wire ATA/IDE cables are color-coded to help you figure out which connector to use for each drive and the host adapter. Use the blue connector for the host adapter on the motherboard or ATA/IDE add-on card. Some motherboards even use blue plastic for some of the ATA/IDE host adapter connectors to make matching the adapter to the cable as easy as possible. The black connector on the other end of the cable is for the primary (master) drive, and the gray connector in the middle of the cable is for the secondary (slave) drive.

Note: Some cables do not use the color-coding described here, but all ATA/IDE cables are made with the primary master connector on one end, the motherboard connector on the other, and the slave connector in the middle.

So basically Cable-Select tells the master from the slave by the postion it is on the cable, black(master) or Grey(slave), the blue end goes to the motherboard

**ALSO without a 80wire cable, UDMA levels will be a mode 2, even if your drive is mode 5 or 6

Edited June 5, 2006 by EAT MY DUST

[PsiMoon314]

Hi,

Using Cable Select these days is not really needed and can cause problems with drive identification.

I always recommend using 80 wire cables and explect Master and Slave settings.

There is a good article about this here: Configuration Using Cable Select

The rest of the articles on this site also have useful information on PATA configurations.

Kind Regards

Simon

[RJM]

Well, thanks guys. I guess that is part of the answer - nobody uses it.

[PsiMoon314]

Hi RJM,

You've got it

It was one of those ideas which seemed to be a good idea but never really caught on.

As a result the hard drive vendors didn't really check to see if their drive inter-operate with other manufacturers so no one really uses it etc ...

Filled into the "Nice Idea but didn't really work" bin.

Kind Regards

Simon

[Andromeda43]

Filled into the "Nice Idea but didn't really work" bin.

That sounds like a good title for a new thread....or just continue the topic here. Whatever.

SATA is so nice because you can only put one drive on a data line and there are NO jumpers to set on the drives. Now there's a "Better Idea" that actually works!

cheers