PC use disk drive to store data and programs by connectors on the motherboard. These connectors are called drive interfaces, and there are two main types: floppy drive and hard disk interfaces. Both are onboard. Most motherboards produced today include both the floppy disk and hard disk interfaces on the motherboard.
They connect to floppy disk drives (FDDs). It is a 34 pin ribbon connector that carries data between the motherboard and any floppy drive installed in the PC.
Hard Disk Connectors
Hard disk drives are accessed over one of a number of bus types, including parallel ATA (P-ATA, also called IDE or EIDE), Serial ATA (SATA), SCSI, Serial Attached SCSI (SAS), and Fibre Channel. FireWire/IEEE 1394 and USB(1.0/2.0) HDD are external units containing generally ATA or SCSI disks with ports on the back allowing very simple and effective expansion and mobility.
Parallel ATA (PATA): originally ATA, is an interface standard for the connection of storage devices such as hard disks, solid-state drives, floppy drives, and optical disc drives in computers. ATA interface evolved from several stages of Western Digital’s original Integrated Drive Electronics (IDE) interface. As a result, many near-synonyms for ATA/ATAPI and its previous incarnations are still in common informal use. After the introduction of Serial ATA in 2003, the original ATA was renamed Parallel ATA. Parallel ATA cables transfers data 16 bits at a time by using 40 or 80 wires ribbon cable and achieving 33, 66, 100 and 133 MB/s with the introduction of 80-wire version and using Ultra DMA (UDMA) mode. Maximum devices that can be attached is four ( two master/slave). They use parallel protocol for data transmission and are not hot pluggable. IDE cables are used in parallel ATA systems are bulkier than SATA cables and can only extend to 40cm long.
Serial ATA (SATA or Serial Advanced Technology Attachment): SATA host-adapters and devices communicate via a high-speed serial cable over two pairs of conductors. It was created in 2003 and offers hot plugging interface with capacity upto 6.0 Gbit/s. It is a serial link — a single cable with a minimum of four wires creating a point-to-point connection between devices. Transfer rates for Serial ATA begin at 150MBps. Main advantage of SATA is the thinner serial cables facilitate more airflow in PC and can extend up to one meter.
Small Computer System Interface (SCSI)
Many motherboards, especially higher-end boards present in servers, include SCSI built in so that SCSI-attached drives can connect directly to the system board without an external adapter.
A SCSI connector is used to connect together computer parts that use SCSI to communicate with each other. Generally, two connectors, male and female, plug together to form a connection. It often use cables to connect devices together by, a socket on motherboard having one end of a cable plugged into it, while the other end plugged into a drive or other device.