Hard disk interfaces

Hard disk interfaces
Hard disks also come in several flavors such as IDE (actually ATA), SCSI and SATA, as do optical
drives. ATA is the most common interface used today. SCSI disks can usually be found on servers.
IDE
Integrated Drive Electronics, more commonly called by its acronym IDE, is an interface for hard
drives. IDE is a marketing term; the real standard is called ATA.
EIDE (Enhanced IDE) or ATA-2 was later developed and increased transfer speed, added 32-bit
transactions and DMA support.
ATA
ATA stands for Advanced Technology Attachment. The ATA -term is commonly used
interchangeably with IDE. The older and more common paraller ATA (P-ATA) is currently being
replaced by serial ATA (SATA).
Most PCs have two IDE controllers on the motherboard. One IDE controller can support two
devices, so four storage devices is usually the maximum. Paraller ATA interface uses ribbon cables
with 40 -pin connectors to connect the hard drives to the motherboard. The cable has usually three
connectors. Of these one is connected to the motherboard and the rest two are left for hard drives.
If two hard drives are connected to the same controller, one must be defined as master and the
other one as slave. This is done with jumpers.
ATA-2 is the real standard for what is widely known as EIDE. ATA-2 introduced higher speed data
transfer modes: PIO Modes 3 and 4 plus Multiword DMA Mode 1 and 2. These modes allow the
ATA interface to run data transfers up to about 16MB/second.
SATA
Serial ATA, also known as SATA or S-ATA, is a bus used to communicate between the CPU and
internal storage devices such as hard drives and optical drives. It is designed to eventually replace
the ATA (also known as IDE) bus. Traditional ATA is beginning to be referred to as Parrellel ATA,
P-ATA, or PATA to avoid confusion.
The main difference between SATA and PATA is in the cabling. SATA does away with the
master/slave relationship of PATA (hence the difference in names), as well as PATA's ungainly
ribbon cables. Instead, SATA has much slimmer and easier to manage cables, which will enable
better airflow through cases. The connectors are keyed, preventing connectors from being plugged
upside down. Truly native SATA drives will have different power connectors also.