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A bus standard that still works well - SATA

This episode will discuss the most common serial bus for HDDs - SATA.


Before we can talk about SATA, we have to talk about HDD. HDDs were popularized quickly and are still the most common storage device for PCs, laptops, and industrial computers because of their large capacities, mature technology, and low costs. Although HDD was invented in the 1950s, its storage capacity did not increase significantly until the 1990s. In addition, the unit storage cost also decreased.


The computer must have controller and disk drive technologies to connect to an HDD. Therefore, in the 1980s, Compaq and Western Digital designed a disk interface for PCs, which became the standard. In 1994, the technology became the US National Standard X3T10-Advanced Technology Attachment, also known as ATA. Shortly before the launch of ATA, IDE was introduced. Western Digital also designed IDE to simplify a controller's functions and significantly reduce costs. Strictly speaking, ATA and IDE are different technologies. ATA is a controller technology, and IDE is a disk drive technology matched with ATA. However, because the two technologies are highly integrated, the names became interchangeable in the industry.


With the rapid advances in computer technology, problems with ATA began to surface. First, circuits are designed in parallel, so they can easily cause electromagnetic interference. Second, the parallel circuits also occupy too much space. Therefore, the industry began developing new standards. In 2002, the serial ATA, or SATA (Serial Advanced Technology Attachment), was introduced, and the traditional ATA was renamed PATA. Compared to PATA, the differential signaling system SATA uses can effectively eliminate noise. This feature allows SATA to operate with a much lower voltage. Furthermore, the serial configuration also takes up less space, so SATA quickly replaced PATA after launch.


The bandwidth of first-generation SATA was 1.5 GB/s, and the transfer speed was 150 MB/s. This was considered high bandwidth and high speed. However, in the 2000s, computer technology was in a period of rapid development. The data capacity of hard drives and the speed of processors were growing exponentially. In response, the SATA organization released SATA2 and SATA3 standards in 2004 and 2009, respectively, which significantly increased bandwidth and speed. In particular, the bandwidth of the SATA3 standard has reached 6 GB/s, and its transfer speed has reached 600 MB/s. Following this, SATA3 also introduced SATA3.1 to SATA3.5, which provided more minor improvements. Apart from SATA3, SATA also introduced eSATA (External Serial ATA) for external drivers and mSATA (mini-SATA) to satisfy the diverse market requirements.


SATA has been around for 20 years. During this period, bus standards with higher bandwidth and speeds were released one after another. In particular, the introduction of PCIe diminished the advantages of SATA. In response to this, SATA introduced SATA Express (SATAe), which uses two PCIe channels and has speeds up to 16 Gbit/s. Because SATAe and eSATA have similar names, users must be careful not to confuse the two.


Generally speaking, SATA is an older bus standard, which PCIe is gradually replacing. However, because it can still provide data transfer speeds of up to 6 Gbit/s, it is still adopted by industrial computers used in specific areas. DFI Inc. also offers related products. For more detailed technical information, please get in touch with the DFI Inc. team.