Internal Drives connect to the motherboard using data cables. The types of data cables are PATA, SATA and floppy disk data cable.
Parallel ATA Data Cables:
The PATA (Parellel ATA) cable can have either 40 or 80 conductors. A PATA cable usually has three 40-pin connectors. One connector at the end of the cable connects to the motherboard. The other two connectors connect to drives.
If multiple hard drives are installed, the "Master" drive should be connected to the end connector on the cable and the "Slave" drive should be connected to the middle connector.
A stripe on the data cable denotes pin 1. Plug the PATA cable into the drive with the pin 1 indicator on the cable aligned to the pin 1 indicator on the drive connector. Many motherboards have two PATA drive controllers known as Primary IDE and Secondary IDE, which provide support for a maximum of four PATA drives. The floppy cable has 34 conductors and there is a twist in the cable, what the twist does is to change the connection of the drive on the far end of the twist so that it is different than the drive before the twist, therefore, the drive at the end of the cable appears as A: to the system and the one in the middle appears as B:
SATA Data Cable:
Serial ATA data cable has a 7-pin connector. One end of the cable is connected to the motherboard. The other end is connected to any drive that has a SATA data connector.
Most of the optical drives have two wired audio connector that can be install to the sound card, when putting audio disk into an optical drive you can plug your head phone to the jack in front of the audio drive and listen to the music.