Speed Evolution in the SATA Interface Standard

The Serial ATA interface , more commonly known as SATA, has been present on our computers since 2001 and continues to be actively used today. In all these years, the standard has evolved a lot, so in this article we are going to look back to see how the speed of the SATA interface on PC has evolved from its creation to our times.

This interface is still today the most used to connect storage devices to the PC. Not long ago, SSDs in M.2 format have appeared that, in many cases, have a PCIe interface (but in some, it is SATA), but their use has not yet spread so much as to replace SATA, at least for now.

SATA

History of the SATA interface

The standard was created by the Serial ATA Working Group OG group, founded in early 2001. The founding members continued to form the Serial ATA II Working Group to continue the development of the next generation of the standard, down to the group we have today. , simply called SATA-IO . The main work of these is to develop the standards related to this interface, the maintenance of its specifications, promotion and sale.

Infografía SATA

SATA has been an accepted and standardized interface since then on the motherboards of personal computers (PCs). Thanks to the specifications that the SATA-IO has been launching each time, logically adopted by the manufacturers, users have been able to enjoy increasing speed in the storage devices .

How the speed of the SATA interface has evolved

The first specification of the standard, called SATA I (revision 1.x) and formally known as SATA 1.5 Gb / s, was the first generation and as its name indicates, its maximum bandwidth was 1.5 Gbps, which means a speed theoretical maximum of approximately 150 MB / s . Its operating frequency is 1,500 MHz, with 1 bit per clock cycle.

The second revision is called SATA II, SATA 2 or SATA 3 Gb / s (revision 2.x) and its maximum bandwidth is 3 Gbps, with a theoretical maximum speed of twice that of SATA I, reaching 300 MB / s . This interface works at 3,000 MHz, with 1 bit per clock cycle as well, and it has the particularity that SATA 2 devices are not backward compatible with SATA 1 interfaces.

Then came the third revision, used today, called SATA III, SATA 3, or SATA 6 Gb / s. Its maximum bandwidth is 6 Gbps, with a maximum speed of twice that of SATA 2, 600 MB / s. It operates at a frequency of 6,000 MHz also with one bit per clock cycle. In this case, they made SATA 3 backward compatible with both SATA II and SATA I.

SATA SATA 2 SATA 3
Frequency 1500 MHz 3000 MHz 6000 MHz
Bits / clock one one one
Coding 8b10b 80% 80% 80%
bits / byte 8 8 8
Real speed 150 MB / s 300 MB / s 600 MB / s

The exception in the standard: SATA Express

This interface was standardized in the SATA 3.2 revision, and instead of continuing with the usual approach of the interface, which was to double its speed with each version, this simply included the PCI Express bus to achieve a higher transfer speed of the 6 Gbps that SATA 3 achieves. It is actually an interface that never came to the fore, but that many motherboards did incorporate.

SATA Express

This interface was first seen on motherboards with an Intel 9 Series chipset (Z97 and H97), compatible with Haswell and Haswell Refresh processors, back in December 2013. However, in mid-2014 the M.2 standard for SSDs, and finally ended up being discarded in favor of these.

SATA Express was capable of providing a bandwidth of up to 16 Gbps, with a theoretical maximum speed of up to 1.6 GB / s.