What is a SATA Chipset?

Joseph S. Thomas

A SATA chipset, otherwise known as a Serial Advanced Technology Attachment (ATA), is a popular interface used in desktop and notebook computers. The SATA interface connects the computer’s motherboard to mass storage hardware, such as optical drives and hard disks. The chipset transmits the data using a high-speed cable with two conductors.

SATA cable connected to a drive.
SATA cable connected to a drive.

A dynamic cabling system connects the SATA chipset to the motherboard and hard disk. Users can connect 2.5-inch (about 63.5-mm) and 3.5-inch (about 88.9-mm) hard disks using the same cable. Each SATA drive must be connected to a power supply and data transmission cable. SATA cables vary in length, but can be as long as 3.3 feet (about 1 m). The small form factor and reduced cable mass make SATA chipsets ideal for laptops and small desktop computers.

A SATA cable.
A SATA cable.

The SATA cable has a direct connection to the storage device, often referred to as a point-to-point infrastructure. The data transmission cable contains seven pins and a coding notch; four pins serve as data connectors, and the other three are ground pins. Data transfers are encoded using a logical algorithm called “8b/10b encoding,” which combines the clock signal with a DC balanced data stream.

SATA cabling attempts to prevent noise, which is one of the most common issues when transferring data over high-speed electrical wiring. Unlike older chipsets, SATA leverages the benefits of differential signaling to reduce distortion during transfers. It has proven to be an improvement to the older PATA connections, which used single-ended signaling.

The SATA chipset replaces parallel ATA (PATA) chipsets commonly used on older computers. SATA provides numerous benefits over PATA, including hot swapping ability, reduced manufacturing costs, faster transfer rates, and fewer cables. SATA cables only need two conductors, whereas PATA chipsets require 16. Additionally, SATA cables contain seven wires, instead of the 80 used in PATA systems.

SATA chipsets also allow users to leverage the benefits of hot-swapping and native command querying (NCQ) via the Advanced Host Controller Interface (AHCI). The motherboard and operating system must support AHCI to work properly. Older operating systems and computers do not support AHCI, forcing the SATA chipset to operate in an ATA emulation environment. SATA chipsets are not backward compatible with legacy PATA hardware. Since there are many PATA systems still in operation today, there are various PATA to SATA adapters available to facilitate the data transfer process.

The SATA chipset requires a wafer-shaped 15-pin power supply connector, which is considerably wider than previous ATA power supplies. The wide form factor reduces the chances of accidentally inserting the cable into the wrong “spot” on the motherboard. The additional pins are required because the connector supports 3.3 volts in addition to the standard 5-volt and 12-volt standard. Other pins on the connector serve as the hotplug and “staggered spinup.”

Since its entrance into the computer market, there have been three revisions to the SATA chipset. Revision 1.0 offered uncoded transfer rates of up to 1.5 gigabits per second (GBps), with actual rates averaging 143 megabytes per second (MBps). Revision 2 SATA chipsets have a native transfer rate of 3.0 GBps, with actual rates averaging 284 MBps.

The most recent revision to the SATA standard increased the maximum throughput to 6 GBps when used with solid state drives (SSD). The third revision optimizes the SATA chipset for multimedia and video streaming via “Quality of Service” enhancements. The third revision requires additional power to support the higher transfer rates and is backward-compatible with previous SATA revisions.

Solid-state hard drives start and operate more quickly than traditional SATA computer hard drives.
Solid-state hard drives start and operate more quickly than traditional SATA computer hard drives.

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