SERIAL ATA

3/18/2000

Serial ATA: An initiative launched in early 2000 by a consortium of major hardware suppliers to define a royalty free high speed disk drive interface. The intent is to eventually phase over the ubiquitous Integrated Drive Electronics/AT Attachment (IDE/ATA) Interface to an inexpensive, high speed, software compatible hardware interface. Intel and many leading disk drive vendors are participating in the initiative. Microsoft is not a member of the initiative as one requirement is NO software changes.

Specifications were completed in Q4 2000. The first serial ATA devices are appear in Q3 2002. Current plans are to continue producing parallel ATA for some time after the introduction of serial ATA. Parallel to serial adapters should be available and all ATA/ATAPI devices will be supported. Serial ATA is not designed as an external signal connector and should not compete with USB2 or IEEE1394. Software for serial ATA is unchanged from that required for parallel ATA.

User drive connection and configuration is expected to be much simplified in Serial ATA. The serial interface will use a smaller connector and lower voltages leading to smaller, cooler running, drives. The thinner cable will eliminate air flow problems caused by the wide parallel ATA ribbon cables. Drives will still have two connectors -- power and data. The locations are standardized and in the same locations in all drive form factors. Data cables up to 1 meter are permitted. Unlike parallel ATA, connectors are not tapped in mid cable. Presumably IDE master/slave no longer applies or has been moved from the drives to the controllers.

The initial speed was originally advertised as will be 1.5 Gbit/s. This seems to have morphed to 1.2Gbits in the final product. (12% faster than ATA133, the fastest parallel ATA standard). 2X and 4X extensions are anticipated later. No drive currently made can approach sustained 133 or 150 MB/sec data transfer rates internally.

www.serialdata.org

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