Anatomy of a Hard Disk Drive

Connectors

Hard disk drives have basically two connectors, one for power and other for exchanging data with the computer. This second connector is better known as “interface”. The most common hard disk drive interface for end-users is called ATA (Advanced Technology Attachment), while SATA (Serial ATA) interface was created to replace ATA and is becoming more popular these days. After the released of SATA, ATA interface started being also called PATA (Parallel ATA). Another famous interface is called SCSI (Small Computer Systems Interface), but it is targeted to servers and rarely seen on PCs targeted to end-users.

Figure 2: Connectors on a hard disk drive using ATA interface.

The master/slave jumper on ATA hard drives can be configured in three different ways:

• Master: this means that this drive will be the only one attached to the cable that connects the hard drive to the computer or will be the first drive in a two-drive configuration.
• Slave: this means that this drive will be the second drive attached to the cable that connects the hard drive to the computer.
• CS (Cable Select): this means that you will use a “special” cable (called CS cable) that the configuration of whether a drive will be master or slave will be made by the position of the hard drive on the cable and not by a jumper configuration on the drive.

Figure 3: Connectors on a hard disk drive using SATA interface.

Serial ATA standard introduced a new power supply plug, which is very different from the standard hard drive power plug. Since Serial ATA is still entering the market, you will find a lot of Serial ATA hard drives with both power connectors, like the one in Figure 3. You need to use just one of them, not the two at the same time.

To learn more about ATA and Serial ATA, we’ve written a complete tutorial on ATA drives and a complete tutorial on Serial ATA drives.

Let’s move on and talk about the components on the logic board.