Serial ATA - It's Time to Get in Line Page 2


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The Need for Change

To understand the need for Serial ATA, we must take a look into the past. The Advanced Technology Attachment (ATA) interface (previously called Integrated Drive Electronics (IDE)) has existed in substantially the same form since 1989, and has become the highest-volume disk drive interface in production. Maxtor, in its role as the patent owner, has led continuous improvements to parallel ATA that has extended its data transfer rate from 3.3 Megabytes per second (MB/s) to 100 MB/s, with only one cable change.

However, as PC processor performance has increased, so have the read/write data rates of hard disk drive (HDD) heads and media. This disk rate is projected to exceed today's 100 MB/s interface bandwidth by 2004. Parallel ATA has kept pace in the past, but is nearing its limit and therefore becoming a performance bottleneck. Serial ATA will eliminate this bottleneck by initially offering 150 MB/s and will also provide significant headroom for future improvements.

In other words, Serial ATA is scalable and allows future enhancements to the computing platform. Parallel ATA (PATA) has been a solid interface — allowing performance scalability and reliable data transmission, but drive rates continue to climb and system designs continue to demand more flexibility and robustness from components. Serial ATA allows the performance and growth to continue without adding cost or utilizing extraordinary means to achieve the requirements.

So, with the preceding in mind, what are the real user benefits of Serial ATA? Let's take a look at some of the evolutionary improvements.

Benefits of Serial ATA

As previously explained, Serial ATA is a high-speed serial link replacement for the parallel ATA attachment of primary internal storage devices. This breaks down to overall system reliability improvements to airflow and thermal dynamics, as well as easier installations and upgrades.

Evolutionary Improvements

Constant evolutionary improvements in the ATA interface have enabled it to remain competitive with other storage interface technologies, despite a number of limitations. Improvements include:

  • ATAPI for support of other peripheral devices, such as CD-ROM drives and tape drives
  • Backward compatibility with older ATA storage devices
  • Cyclic redundancy checking (CRC) for improved data protection and greater overall data integrity
  • Enhanced Integrated Drive Electronics (EIDE) extensions for faster HDD access and logical block addressing (LBA)
  • Multiple data-transfer modes, including Programmed Input/Output (PIO), direct memory access (DMA), and Ultra DMA (UDMA)

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