Editing SATA (section)

== Backward and forward compatibility ==

=== SATA and PATA ===
[[File:PATA hard disk with SATA converter.png|thumb|PATA hard disk with SATA converter attached]]
At the hardware interface level, SATA and PATA ([[Parallel ATA|Parallel AT Attachment]]) devices are completely incompatible: they cannot be interconnected without an adapter.

At the application level, SATA devices can be specified to look and act like PATA devices.<ref>
{{cite web |url=http://www.sata-io.org/documents/serialata%20-%20a%20comparison%20with%20ultra%20ata%20technology.pdf |archive-url=https://web.archive.org/web/20120327214126/http://www.sata-io.org/documents/serialata%20-%20a%20comparison%20with%20ultra%20ata%20technology.pdf |title=A comparison with Ultra ATA Technology |publisher=SATA-IO |archive-date=2012-03-27 |access-date=2014-08-15}}</ref>

Many motherboards offer a "Legacy Mode" option, which makes SATA drives appear to the OS like PATA drives on a standard controller. This ''Legacy Mode'' eases OS installation by not requiring that a specific driver be loaded during setup, but sacrifices support for some (vendor specific) features of SATA. Legacy Mode often if not always disables some of the boards' PATA or SATA ports, since the standard PATA controller interface supports only four drives. (Often, which ports are disabled is configurable.)

The common heritage of the ATA command set has enabled the proliferation of low-cost PATA to SATA bridge chips. Bridge chips were widely used on PATA drives (before the completion of native SATA drives) as well in standalone converters. When attached to a PATA drive, a device-side converter allows the PATA drive to function as a SATA drive. Host-side converters allow a motherboard PATA port to connect to a SATA drive.

The market has produced powered enclosures for both PATA and SATA drives that interface to the PC through USB, Firewire or eSATA, with the restrictions noted above. [[Peripheral Component Interconnect|PCI]] cards with a SATA connector exist that allow SATA drives to connect to legacy systems without SATA connectors.

=== SATA 1.5&nbsp;Gbit/s and SATA 3&nbsp;Gbit/s <span class="anchor" id="FORCE-150"></span><span class="anchor" id="OPT1-ENABLED"></span> ===
The designers of SATA standard as an overall goal aimed for backward and [[forward compatibility]] with future revisions of the SATA standard. 
To prevent interoperability problems that could occur when next generation SATA drives are installed on motherboards with standard legacy SATA 1.5&nbsp;Gbit/s host controllers, many manufacturers have made it easy to switch those newer drives to the previous standard's mode.
Examples of such provisions include:
* Seagate/Maxtor has added a user-accessible jumper-switch, known as the "force 150", to enable the drive switch between forced 1.5&nbsp;Gbit/s and 1.5/3&nbsp;Gbit/s negotiated operation.
* Western Digital uses a jumper setting called ''OPT1 enabled'' to force 1.5&nbsp;Gbit/s data transfer speed (OPT1 is enabled by putting the jumper on pins 5 and 6).<ref>{{cite web|url=https://support-en.wd.com/app/answers/detailweb/a_id/1991|title=Windows: Install Serial ATA, EIDE, SSD Drive and Set Jumper Settings|archive-url=https://web.archive.org/web/20221130233258/https://support-en.wd.com/app/answers/detailweb/a_id/1991|date=20 August 2018|access-date=30 November 2022|archive-date=30 November 2022|work=Western Digital|url-status=live}}</ref>
* Samsung drives can be forced to 1.5&nbsp;Gbit/s mode using software that may be downloaded from the manufacturer's website. Configuring some Samsung drives in this manner requires the temporary use of a SATA-2 (SATA 3.0&nbsp;Gbit/s) controller while programming the drive.

The "force 150" switch (or equivalent) is also useful for attaching SATA 3&nbsp;Gbit/s hard drives to SATA controllers on PCI cards, since many of these controllers (such as the [[Silicon Image]] chips) run at 3&nbsp;Gbit/s, even though the PCI bus cannot reach 1.5&nbsp;Gbit/s speeds. This can cause data corruption in operating systems that do not specifically test for this condition and limit the disk transfer speed.{{Citation needed|date=June 2014}}

=== SATA 3&nbsp;Gbit/s and SATA 6&nbsp;Gbit/s ===
{{Expand section|date=October 2011}}
SATA 3&nbsp;Gbit/s and SATA 6&nbsp;Gbit/s are compatible with each other. Most devices that are only SATA 3&nbsp;Gbit/s can connect with devices that are SATA 6&nbsp;Gbit/s, and vice versa, though SATA 3&nbsp;Gbit/s devices connect with SATA 6&nbsp;Gbit/s devices only at the slower 3&nbsp;Gbit/s speed.

=== SATA 1.5&nbsp;Gbit/s and SATA 6&nbsp;Gbit/s ===
{{Expand section|date=July 2013}}
SATA 1.5&nbsp;Gbit/s and SATA 6&nbsp;Gbit/s are compatible with each other. Most devices that are only SATA 1.5&nbsp;Gbit/s can connect with devices that are SATA 6&nbsp;Gbit/s, and vice versa, though SATA 1.5&nbsp;Gbit/s devices only connect with SATA 6&nbsp;Gbit/s devices at the slower 1.5&nbsp;Gbit/s speed.