Configuration Using Cable Select

An alternative to the standard master/slave jumpering system used in the vast majority of PCs is the use of the cable select system. As the name implies, with this system the cable--or more correctly, which connector on the cable the device is attached to--determines which device is master and which is slave.

The intention is to save the user from having to change jumpers when changing a hard disk from master or slave. To use cable select, you must set both hard disks to the "cable select" (CS) setting, usually using a jumper. Then, you use a special cable; normally it has three connectors with the middle one intended for the motherboard (or hard disk controller). The other two connectors are modified so that one of them will tell the drive to which it is connected to be the master and the other will tell its drive to be the slave. The drives can be switched by changing which connector on the cable they use. The concept is actually very similar to the way that the floppy disk interface cable works, which is in fact the standard way that floppies are configured in most PCs.

There are several problems with the cable select system for IDE. The biggest one is that it is non-standard; very few PCs out there use cable select. This can make it confusing when you try to upgrade your PC, because most people are used to the jumpers on the disks controlling master and slave, not the cable. Second, the cable is much harder to find since it is rarely used. Finally, you lose flexibility in the physical layout of the inside of the case. The IDE cable is relatively short and being forced to put the master and slave at specific locations on the cable means that you restrict where they can be placed in the case.

Cable select is intended to save the hassle of changing jumpers, but it can actually force the much bigger hassle of physically relocating the drive in the case. Virtually all hard disks ship from the manufacturer jumpered as master or single drives, and most CD-ROMs ship as slaves. Given this, you are going to have to put the hard disk into cable select mode through a jumper before you start anyway. Cable select is an interesting idea, but it has never caught on and I don't think it is likely that it will, primarily because of inertia.

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