SATA, short for Serial ATA, and ATA, short for Advanced Technology Attachment, are both interface standards used for connecting storage devices like hard drives and optical drives to a computer’s motherboard. Both were developed to replace the earlier Parallel ATA (PATA) standard.
SATA was first introduced in 2001 by a group of companies including Intel, Seagate, Dell, and Maxtor, with the aim of providing a serial interface that offered improved speeds compared to the parallel PATA interface. The SATA 1.0 standard provided transfer speeds up to 150MB/s. Over the years, updated SATA standards have increased speeds up to SATA 3.0’s 6Gb/s in 2009 [1].
The original ATA standard was developed starting in 1986 and provided transfer speeds up to 16MB/s. This evolved into Enhanced IDE (EIDE) in the 1990s and then ATA/ATAPI with speeds up to 133MB/s. ATA standards have mainly been focused on the physical interface, with SATA defining the full transmission protocol [2].
Both SATA and ATA are commonly used to connect internal hard drives, solid state drives, optical disc drives like CD/DVD/Blu-Ray drives, and other storage devices inside a computer. They allow these devices to integrate with the motherboard and operating system.
SATA Interface and Connectors
SATA stands for Serial Advanced Technology Attachment. It is a storage interface used to connect host bus adapters to mass storage devices such as hard disk drives, solid-state drives, and optical drives. There have been several versions of the SATA interface over the years:
SATA I – This was the first SATA generation introduced in 2003, supporting speeds up to 1.5Gb/s.
SATA II – Released in 2004, SATA II doubled the speed to 3Gb/s.
SATA III – Introduced in 2009, SATA III increased speeds to 6Gb/s.
The SATA interface uses point-to-point connections. Cables have a 7-pin connector, with data transmitted in serial fashion over two pairs of conductors. SATA cables are thin, flexible and allow easy installation and routing within a system. Common SATA cable lengths are 18 inches, 24 inches, 36 inches and 48 inches. The thin SATA cables help with airflow and reduce clutter inside computers compared to the thicker Parallel ATA cables used before SATA was introduced.
SATA connectors have two pairs of data signals and power. The data pairs are transmitted as differential signals. There are seven pins arranged in an L-shape, with the longer leg containing the power and ground signals. The shorter leg holds the two data signal pairs. The asymmetric design allows the connectors to be keyed to prevent incorrect orientation when plugged in.
ATA Interface and Connectors
The ATA (AT Attachment) interface, also known as IDE (Integrated Drive Electronics), was introduced in the late 1980s and is the original hard drive interface standard used before SATA. Some of the key ATA interface types include:
- ATA – Base standard parallel ATA interface
- ATAPI – ATA Packet Interface, an extension to allow connecting optical drives and tape drives
- EIDE – Enhanced IDE, an extension to original ATA allowing bigger drive capacities
- Ultra ATA – Faster version of ATA introduced in the late 90s
The ATA interface uses a 40-pin or 44-pin ribbon cable to connect storage devices to a PC’s motherboard. The cable has three connectors – one that plugs into the motherboard, and two device connectors that allow connecting a master and slave drive. The ribbon cable limits the maximum length to 18 inches.
The 44-pin cable adds support for supplying 3.3V power, while the 40-pin version only supplies 5V and 12V. The cable itself does not supply power, which comes directly from the power supply via 4-pin Molex connectors.
Overall, ATA cables and interfaces provide parallel communication between drives and PC, with speeds maxing out at 133 MB/s with Ultra ATA. The ribbon cable limits length and data speeds compared to newer SATA interfaces.
Speed Comparison
SATA offers much faster maximum interface transfer speeds than ATA. The original ATA specification topped out at 133 MB/s, while SATA began at 150 MB/s for the 1.0 specification released in 2003. Each successive generation has increased speeds further:
ATA 133 MB/s max (ATA-6)
SATA 1.0 150 MB/s max
SATA 2.0 (SATA 3Gbps) 300 MB/s max
SATA 3.0 (SATA 6Gbps) 600 MB/s max
The latest SATA revision, SATA 3.2, theoretically supports up to 1969 MB/s transfer speeds. In real-world usage, SATA 3.0 SSDs can reach 550+ MB/s sequential reads, while the fastest SATA HDDs top out below 200 MB/s. For comparison, a 7200 RPM ATA drive averages under 100 MB/s sequential reads.
So in summary, SATA offers between 1.5x to over 10x higher maximum bandwidth versus ATA, enabling substantially faster data transfers.
Usage Scenarios
SATA is the newer standard and is commonly used in newer computers and storage devices. Some common uses of SATA include:
- Hard drives in modern desktops and laptops
- Solid state drives (SSDs)
- Optical disc drives like DVD and Blu-ray drives
ATA is an older standard that has largely been replaced by SATA in newer systems. Some places ATA may still be used include:
- Older hard drives in legacy computer systems
- Some external storage enclosures and adapters
- As a fallback interface in some newer systems that still provide ATA support
Overall, SATA is the predominant standard used for internal storage in modern computers while ATA use is declining. However, ATA devices and adapters still exist to provide backwards compatibility with older systems.
Compatibility
SATA and ATA have different levels of backward and forward compatibility. SATA is fully backward compatible with legacy ATA and ATAPI devices (https://docs.rs-online.com/f1f5/0900766b80e5438d.pdf). This means that SATA controllers and ports can interface with older ATA drives. However, the speeds will be limited to the maximum speed of the older ATA drive.
In terms of forward compatibility, ATA drives do not work directly with SATA ports and controllers. An adapter or converter is required to connect an ATA drive to a SATA port (https://www.daniweb.com/hardware-and-software/microsoft-windows/threads/155397/0x0000007b-0xf7abe524-error). So while SATA is backward compatible, ATA is not forward compatible without an adapter.
Power Delivery
SATA and ATA use different methods for delivering power to devices. SATA utilizes a separate power cable that provides 3.3V and 12V power rails to devices, allowing for higher power draw compared to ATA. This enables support for more power-hungry components like SSDs. In contrast, ATA delivers power directly over the data cable, limiting the amount of power that can be supplied. The maximum power draw for ATA is around 133 Watts, whereas SATA can deliver up to 900 Watts over the separate SATA power connector. This gives SATA an advantage for supporting devices with higher power requirements.
According to TechTarget, “SATA introduced a power connector separate from the data interface, allowing the data cable to be thinner and more flexible.” (1) The dedicated power cables and increased power delivery make SATA better suited for modern storage devices and components.
Hot Swappability
One of the key differences between SATA and ATA is hot swappability – the ability to connect and disconnect devices without shutting down the entire system. SATA supports hot swapping while ATA does not.
With SATA, you can safely connect and disconnect hard drives and solid state drives while the computer is running. This avoids any downtime from having to fully shut down and restart the computer when swapping drives.
In contrast, ATA does not allow hot swapping. The ATA interface requires a system shutdown whenever an ATA drive needs to be added, removed, or replaced. Attempting to hot swap ATA drives could lead to data loss or corruption.
The hot swappability of SATA is a major advantage for server and storage environments where uptime is crucial. System administrators can swap out failed drives without any disruption to operations. Overall, SATA’s support for hot swapping helps improve performance, uptime, and manageability.
Cost Comparison
Generally, SATA cables and devices tend to be more expensive than their ATA counterparts. This is largely due to SATA being newer technology that offers faster transfer speeds.
For example, a basic 40-pin ATA cable can be purchased for under $5, while a SATA cable typically costs between $5-$10 for a similar length cable. SATA solid state drives (SSDs) usually cost around 20-50% more than similar capacity ATA/IDE SSDs.
However, the price difference is narrowing as SATA becomes more ubiquitous and replaces ATA technology. The speed and performance benefits of SATA often make the small additional cost worthwhile for many consumers, especially for primary storage drives.
According to an analysis by Markercontent.com, a 1TB SATA hard drive retails on average for $10 more than a comparable 1TB ATA drive. But the rotational speed of the SATA drive is 50-100% faster at 7200 RPM versus 5400 RPM for ATA.[1]
So in summary, while SATA cables and devices still cost slightly more than ATA presently, the performance benefits generally outweigh the small price premium for most users.
[1] https://www.markercontent.com/articles/technology/ata-vs-sata-hard-drives-164955
Summary
SATA and ATA are both drive interfaces used to connect storage devices to a computer, but have some key differences. SATA is the newer standard, introduced in 2003 to replace the older parallel ATA standard. SATA uses a high-speed serial connection, while ATA uses a parallel connection. This allows SATA to achieve much faster transfer speeds, with current versions reaching up to 16 Gb/s, compared to ATA’s maximum of 133 Mb/s.
SATA uses much thinner cables that allow improved airflow and cable management in modern PC cases. SATA is designed for hot swapping and supports power management features. The most common uses of SATA are for connecting SSDs, HDDs, and optical drives in desktop PCs and servers. The smaller size of SATA ports also makes the interface well-suited for external storage devices and laptop drives.
ATA is now obsolete for most applications but was very common for many years for HDDs in desktop PCs. Some older systems may still support ATA drives but have limited transfer speeds. ATA is missing many advanced features of SATA and lacks support for modern large-capacity drives over 2TB. In summary, SATA has almost entirely replaced ATA due to its faster speeds, smaller size, hot swap support, and advanced power management.
