Serial ATA Bus

Serial ATA (Advanced Technology Attachment)

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Serial ATA Signal Assignments

SATA Cabling Diagram

SATA Interface
The Serial ATA [SATA] bus is defined over two separate connectors,
one connector for the data lines and one for the power lines [shown left].
A Serial ATA Hard drive may also have a third connector for legacy PATA power connections.
The PATA power connector may be used in instead of the SATA power cable
to supply a connection which is more rugged and reliable then the SATA-1 power connection.
The PATA interface is not visible in the diagram.

The Serial ATA interface cable consists of four conductors in two differential pairs,
plus three ground connections.
The cable size may be 30 to 26 AWG with a maximum length of one meter (39.37 inches).

SATA Data pinout

**SATA PinOut, Data**
Pin #	Signal name	Signal Description
1	GND	Ground
2	A+	Transmit +
3	A-	Transmit -
4	GND	Ground
5	B-	Receive -
6	B+	Receive +
7	GND	Ground

SATA Power pinout

**SATA PinOut, Power**
Pin #	Signal name	Signal Description
1	V33	3.3v Power
2	V33	3.3v Power
3	V33	3.3v Power, Pre-charge, 2nd mate
4	Ground	1st Mate
5	Ground	2nd Mate
6	Ground	3rd Mate
7	V5	5v Power, pre-charge, 2nd mate
8	V5	5v Power
9	V5	5v Power
10	Ground	2nd Mate
11	Reserved	-
12	Ground	1st Mate
13	V12	12v Power, Pre-charge, 2nd mate
14	V12	12v Power
15	V12	12v Power

PATA Power pinout

**IDE Power Connector Pin Out**
Pin #	Signal Function	18 AWG Wire

1	+12V DC	Yellow
2	+12V Return	Black
3	+5V Return	Black
4	+5V DC	Red

To date all new mother board designs are shipping with one or more SATA interfaces. Some motherboard's also have the Legacy PATA interface to handle older Hard Disk Drives [HDD]. Place your main Disk Drives on the Serial ATA interface if possible and the older drives on the PATA interface ~ as a back-up drive. The SATA interface is much faster then the PATA interface, but depending on the disk platter speed, a transfer increase may not be seen. Here is a chart of Hard Drive Transfer Speeds.

SATA signal names are with respect to the Host, the device connected to the host reverses the signal names. Transmit pins connect to Receive pins on the other device. The SATA connector is keyed at pin 1. These pin outs for the Serial ATA connector are not compatible with the legacy PATA connector.

The Serial ATA interface [SATA] is the serial version of the IDE [ATA] spec. SATA uses a 4 conductor cable with two differential pairs [Tx/Rx], plus an additional 3 grounds pins and a separate power connector. Data runs at 150MBps [1.5GHz] using 8B/10B encoding and 250mV signal swings, with a maximum bus length of 1 meter. SATA enhancements move the data transfer speed to; 300MBps [3.0Gbps], and then 600MBps [6.0Gbps]. The current speed for SATA is 300Mbps [3Gbps]. Shielded external SATA [eSATA] data cable runs out to a maximum of between 3 feet and 6 feet. eSATA cables are used external to the chassis or case.

Related SATA acronyms;

Direct Attached Storage [DAS], is a drive connected to a server.
Networked Attached Storage [NAS], is a drive connected to a network.
Storage Area Network [SAN], is a system of drives.
Direct Access Storage Devices [DASD], is a fast-access drive connected to computer.
Host Bus Adapter [HBA], is an interface between a computer and a drive.

Fun (or forgotten) fact
What does the acronym SATA stand for? Most sites gloss over it and only provide "Serial ATA", but what is the ATA part? Turns out that has quite a history. and only a very few sites will report that the acronym came about when IDE was standardized, the name for the new standard was (as most report) "ATA" or "AT Attachment". What the "AT" stands for? Who only lists part of an acronym when giving a definition! I don't blame them, This one is buried and all but forgotten, a sure beer bet for your geek buddies as they will almost certainly not know this one.
Drum roll please..... The complete definition for SATA is: "Serial Advanced Technology Attachment"<---Font is white on white, highlight with mouse to reveal the answer.
That should be worth at least a buck!

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