Serial ATA

This is a new one for me and probably for most others of you. Serial ATA is a new way of connecting your storage devices. You will all be used to the way we connect IDE devices to out motherboards. We have a wide 40/80 pin wire plugged into both the motherboard and the storage device. These wires are big and bulky and often get in the way of a lot of other things inside the case. They are also based on Parallel data transmission which sends data in parallel cause interference with other signals. Serial connectors only have a send and receive cause much less problems in that respect.

The serial cable is only a small thin cable as opposed to the bulky IDE cables. This helps with the airflow around the case and helps system cooling. The cables themselves can also be longer than the set limit of 40cm of the IDE cables. This makes it a lot easier to connect those awkward HD's at the top of a tower case.

Lets have a look in more detail at the Serial ATA specification and the impact it will have on future storage devices.

Serial Over Parallel

Why choose serial over the current Parallel data transfer method. Well there are two main reasons for this. Firstly Having data sent in parallel requires a lot of signal being sent at the same time, this causes electrical interference and can have problem, using serial transfer means you only need a send and receive signal.

The second reason is if you are sending data in parallel you have to have a lot more wires. You know that an IDE cable can be a real pain when trying to keep system cooling running smoothly. They also get in the way of other wires running throughout the system.

All the other data transfer standard we use today are based on the serial data transfer system, USB, Ethernet and Firewire are all based on serial data transfer.

Data Transfer Rate

The current specification for serial ATA allows for a max data transfer of 150Mb/s That would be the same as a ATA150 specification for the current HD rating. Serial ATA II specification was released with a transfer speed of 300Mb/s or S-ATA/300. Data transfer speed of 300Mb/s can be achieved with a Serial ATA II capable motherboard and a S-ATA II hard drive. 600Mb/s Serial ATA bus has been developed but at present the technology that hard drives work off make them incapable of reaching the 600Mb/s transfer speed.

The Cable

The picture below show you the difference in size between the older IDE cable on the left and the new Serial ATA cable

As you can see the Serial ATA cable is a great deal smaller and so is less intrusive in the case. Also the IDE cable is limited to 40 CM in length while the serial ATA cable does not have this restriction. Meaning that you can now connect those awkward devices located at the top of the large tower case.

Hot Plugging

Hot plugging is something that is brand new for these devices, in fact I've never even thought it would be made. However its here, Hot plugging allows you to connect and disconnect serial ATA devices without powering down the system. OS's within the last few years will pick up on the new device as soon as its been plugged into the system.