Why Serial ATA    

Serial ATA (SATA), an evolutionary high-performance interface for storage devices to replace the Parallel ATA, is used to connect ATA and ATAPI devices, including CDs, DVDs, tapes devices, high capacity removeable devices, zip drives, and CD-RWs.  

Compare with parallel ATA interface, Serial ATA addresses some shortcomings and provides a scalable platform to support several generations of future storage devices.  

Serial ATA is a drop-in solution that is compatible with today's software, which runs on the new architecture without modification. It provides for systems which are easier to design, with cables that are simple to route and install, smaller cable connectors, improve silicon design, and lower voltages which alleviate current design requirements in Parallel ATA.

Lower Voltage. Parallel ATA requires integrated circuits to tolerate input signals as high as 5 volts. Serial ATA reduces the signaling voltages to approximately 250 millivolts (¼ volt).

Pin Efficiency. The parallel ATA interface has 26 signal pins going into the interface chip. Serial ATA uses only 4 signal pins, improving the pin efficiency and accommodating a highly integrated chip implementation.

Improved Cable and Connector Plant. The parallel ATA cable and connector plant is a bulky cable made up of unwieldy 80 conductor ribbon cables and 40 pin header connectors. Serial ATA uses a much smaller serial cable similar in appearance to modern telephone cables. Eliminating the cable nest improves the systemˇ¦s airflow and cooling, and offers greater freedom in chassis design.

Master-Slave Interaction. With todayˇ¦s parallel ATA implementation, pairs of devices share a common cable in a master-slave relationship. This interaction between devices results in the available bandwidth being shared between the devices. Additionally, since the devices on the cable interact, they must be jointly qualified, resulting in the substantial expansion of the system integratorsˇ¦ qualification matrix in order to comprehend all possible combinations of devices. Serial ATA is a point-to-point interface where each device is directly connected to the host via a dedicated link. Each device, therefore, has the entire interface bandwidth dedicated to it, and there is no interaction between devices. This means software can be streamlined, eliminating the overhead associated with coordinating accesses between the master and slave device sharing the same cable. 

Serial ATA is compatible at the register level with parallel ATA. This means Serial ATA requires no changes to existing software and operating systems in order to function, and it provides backward compatibility with existing operating environments. It has already been demonstrated to run with Microsoft Windows* 98, Microsoft Windows 2000, and Linux operating systems without the need for any special software drivers.