Serial ATA and the 7 Deadly Sins of Parallel ATA Print E-mail
Written by Michael Schuette   
Sep 12, 2002 at 04:00 PM

Serial ATA and the 7 Deadly Sins Of Parallel ATA

Mass storage media are currently pushing the envelope of parallel interfaces. Cable properties, connector legacies and signaling protocols have reached a point where trading off one potential problem spot against another has left no more room for technical and design navigation. Cross talk, ground bouncing and signal ringing, along with too tight timing windows have left no margins for improvement beyond ATA PI-7 (UATA-133) and, thus, the industry is confronted with the paradox that the actual storage media such as hard disk drives outperform the connectivity. Other issues like lack of hot swap capability and difficult trace routing on the PCB have done the rest to call for a radical change of guards. Within the next few weeks / months, we will experience a somewhat radical transition from parallel to serial ATA that will deliver higher speed, improved reliability and easier installation along with the introduction of some other nifty features like tagged command queuing to the commodity drive world.

What are the real pitfalls of parallelism? How can serialization address the issues and what can we expect in terms of the industry supporting the new kids on the block? Time to put on those big reading glasses and the thinking cap (it may get a bit technical at times) ....

Taking theory to the testlab, we have dissected the Seagate Barracuda SATA V and reveal the first prototype of the next generation of drive including some mindblowing performance.

After over 15 years, internal storage media such as hard disk and optical drives finally meet the limitations of the currently used parallel interface. Parallel interfaces, in particular, the advanced technology attachment (ATA) standard have evolved since the mid 1980s from transfer rates of 3.3 MB/sec in ATA-1 to currently 100 MB/sec in ATA PI-6, also known as Ultra ATA 100. Contrary to common belief, Ultra ATA133 is not yet fully standardized, however, finalization of the standard is well on its way and will be listed as ATA PI-7 or UATA PI Mode7 in the future.

Serial and parallel connectors side by side. Not only has the data interface changed, also the power connectors have been given a new face. Best of all, there are real reasons behind this and those reasons are prime examples of extremely smart engineering. We'll have all the details later.....

It is clear that parallel interfaces are pushing the limitations of what can be achieved without violating the laws of physics while maintaining a reasonable cost point. It is also clear that storage devices are the one imminent performance bottleneck in the overall system performance. Combined, these two points pose a strong argument for embarking on new technology with the goal of enabling faster mass data access and higher overall throughput. Before going into specifics, here is a short outlook into what we'll discuss in the rest of this article:

Within the next few weeks, Serial ATA will be introduced to the mainstream PC at an original peak transfer rate of 150 MB/sec and a roadmap leading to up to 600 MB/sec throughput in 2007. What are the reasons to turn the back on the established parallel interface and how is the industry addressing the challenge for faster mass storage media? We'll be dissecting the technology of the old, discuss possibilities for transition or migration between standards and show the advantages of the new.

Last Updated ( Jul 20, 2010 at 10:01 AM )
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