What is SATA and how does it work with my computer

Why did they SATA My Computer?

Throughout the history of personal computers, they have gone through many changes. The early computers were incredibly simple devices, compared to what we have today, running much slower, using much less memory, and having much smaller bus sizes. As computer technology has grown, many of those old standards have had to be replaced, because they just aren’t fast enough to carry the high data load that modern computers require.

While many of these standards have survived several generations of computers, they eventually reach a point where they have to be changed, in order to allow computers to keep growing and improving. New standards are created and the old ones fade away.

Computer Buses

Amongst these changes to computer standards have been changes to the data buses used by computers. A bus is a series of wires or copper lands on a computer motherboard, which are designed to carry data information to many different places. A common bus saves in the design and manufacture of these devices, by allowing the same wires or lands to be used to carry data (information) to many different places. The device that should read the information being carried across the bus is informed that the information coming is for it, much like a telephone rings to let one know that the call coming in is for them.

Early computers used an 8 bit bus. That means that they had only eight wires, and could only transmit eight bits of data at one time. This quickly grew to 16 bits to accommodate IBM’s 286. With the development of the 386, this had to change again, jumping up to 32 bits. It has stayed there up until recent times, when high performance computers started using 64 bit busses.

Buses run in parallel, meaning that one byte (a word of digital information) is transmitted at a time, with the size of the byte being limited by the number of lines in the bus. This is what drove the expansion of those early busses, as a 16 bit byte can accomplish over four times what an 8 bit bus can.

Serial or Parallel Data?

IDE PATA connectionSince computer speeds and bus speeds were much slower in those earlier computers, everything that could be was run through parallel busses, rather than serial ports. What’s the difference? Parallel busses take all the bits of a byte and transmit them at the same time, over separate lines. Serial busses send the bits in a bite across the line one at a time, like cars on a train. It’s considerably slower, because a 32 bit byte takes 32 clock cycles to transmit, rather than one to transmit the same data in parallel.

In more recent times, computer speeds have increased to the point where the limiting factor isn’t the computer processor or the buss that slows things down, but the hard drives and other peripherals. So, it has become practical to use serial busses for transmitting data, where parallel busses were needed before.

The most obvious manifestation of this is the USB, which stands for Universal Serial Bus. It’s a serial bus, which is intended for use with all of a computer’s peripherals. Devices which needed parallel busses before, like printers, are now receiving all their data off of a single serial line, and still working faster.

On to SATA

SATA stands for Serial ATA. It has replaced the old IDE (integrated drive electronics) communications standard for communicating with hard drives of all kinds. The old IDE drive has been renamed PATA (Parallel ATA), just to use the same nomenclature style for both. While this has caused confusion for old-time computer users, they have been able to adapt.

SATA and eSATA connectionsThere are two major advantages that the SATA interface provides over the PATA. First of all, it provides faster communication than the PATA ever could. This increase in data transfer speed helps prevent the hard drive or optical drives on a computer from delaying the computer’s processing. While the SATA interface can’t speed up the hard drive, it can ensure that the data that comes off the hard drive is transferred as rapidly as possible.

The second advantage that the SATA provides is a smaller, less expensive cable. This reduces computer costs slightly, by using less copper wires and smaller connectors. At the same time, for those who remember their computers filled with IDE cables, it makes the inside of the computer “cleaner” which makes them easier to work on and improves airflow for cooling.

When used with solid state drives, SATA provides much faster data transfer rates and seek rates than were ever possible with PATA. Solid state drives are essentially large flash memories. As such, they have no moving parts and can operate at much faster speeds than conventional hard drives, which have a disk inside them.

sata adapter converterAdapting to SATA

Since the SATA interface is an actual change in the way that data is moved, you can’t use a simple cable adapter to connect one to the other. However, there are adapter boards, which mount to the back of a PATA drive, allowing a SATA connection to the drive. This allows older hard drives which contain important information to be connected to newer computers for data transfer. These adapters can either be installed permanently, or used temporarily.

At the same time that the SATA interface was introduced, the power supply connector for hard and optical drives was changed from the old Molex connector to a SATA compatible connector. This changeover can be made with a simple adapter from one connector style to the other.


SATA has been so effective, that a second generation of the SATA interface has been developed called eSATA. This is an “external” version of the SATA interface, which can be used for connecting hard and optical drives to a computer externally. They provide a faster data transfer time than what USB can provide, plus don’t require sharing of the USB buss with other devices.


Rich Murphy