Is SATA 1.5 interface Compatible with SATA Drive 2?

Backward and forward compatibility
[edit] SATA and PATA

At the device level, SATA and PATA (Parallel AT Attachment) devices remain completely incompatible—they cannot be interconnected. At the application level, SATA devices can be specified to look and act like PATA devices.[23] Many motherboards offer a "legacy mode" option, which makes SATA drives appear to the OS, like PATA drives on a standard controller. This eases OS installation by not requiring a specific driver to be loaded during setup but sacrifices support for some features of SATA and, in general, disables some of the boards' PATA or SATA ports, since the standard PATA controller interface supports only 4 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 as standalone "dongles." When attached to a PATA drive, a device-side dongle allows the PATA drive to function as a SATA drive. Host-side dongles allow a motherboard PATA port to function as a SATA host port.

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. PCI cards with a SATA connector exist that allow SATA drives to connect to legacy systems without SATA connectors.
[edit] SATA 1.5 Gbit/s, SATA 3 Gbit/s and SATA 6 Gbit/s

The designers of SATA aimed for backward and forward compatibility with future revisions of the SATA standard.[24][valid reference needed, this one is not valid any more]

According to the hard drive manufacturer Maxtor, motherboard host controllers using the VIA and SIS chipsets VT8237, VT8237R, VT6420, VT6421L, SIS760, SIS964 found on the ECS 755-A2 manufactured in 2003, do not support SATA 3 Gbit/s drives. Additionally, these host controllers do not support SATA 3 Gbit/s optical disc drives. Users with a SATA 1.5 Gbit/s motherboard with one of the listed chipsets should either buy an ordinary SATA 1.5 Gbit/s hard disk, buy a SATA 3 Gbit/s hard disk switchable to 1.5 Gbit/s, or buy a PCI or PCI-E card to add full SATA 3 Gbit/s capability and compatibility.

To address interoperability problems many manufacturers allow to switch drives to the SATA1 mode. The largest hard drive manufacturer, Seagate/Maxtor, has added a user-accessible jumper-switch known as the Force 150, to switch between 1.5 Gbit/s and 3 Gbit/s operation. Western Digital uses a jumper setting called OPT1 Enabled to force 1.5 Gbit/s data transfer speed (OPT1 is used by putting the jumper on pins 5 & 6). Samsung drives can be switched to 1.5 Gbit/s mode by using software downloadable from the manufacturer website. This needs a SATA2 controller to use temporarily while programming the drive.

The Force 150 switch is also useful when placing SATA 300 hard drives on SATA controllers on PCI cards, since many of these controllers (such as the Silicon Images chips) will run at SATA300 even though the PCI bus cannot even reach SATA150 speeds. This can cause data corruption in operating systems (ie: FreeBSD) that do not specifically test for this condition and limit the disk transfer speed.