What does it indicate if a hard drive is pinned as CS?

When a hard drive is pinned as CS, it indicates that it is configured as "Cable Select." This is a designation commonly associated with IDE (Integrated Drive Electronics) drives, especially those using the older IDE interface. In a Cable Select configuration, the master or slave role of the drive is determined by the position of the drive on the IDE cable rather than by jumper settings on the drive itself.

Under this configuration, if the drive is connected to the end of the cable, it will be recognized as the master drive, while the drive connected to the middle connector will be the slave drive. This feature simplifies the installation process for users, as they do not need to manually set jumpers for master/slave configuration.

While it's true that SATA and SCSI drives also have different types of configurations and connection protocols, the specific designation of "CS" is traditionally linked to IDE drives. Therefore, identifying a hard drive pinned as CS directly points to it being an IDE drive.