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Articles: Storage

External SerialATA Interface: First Facts about the Unannounced Standard (page 4)

Category: Storage

by Nikita Nikolaichev

[ 03/01/2004 | 10:37 AM ]

The connectors for external SerialATA devices have also undergone serious changes. In order to improve the protection against EMI (ElectroMagnetic Interference) and ESD (ElectroStatic Discharge) the developers paid special attention to proper screening. The requirements to mechanical specifications of the connectors have also grown tougher. The diversity of cables and connectors of the new type is determined by the above mentioned support of the multi-channel interfaces.

A part of the specification related to the multi-channel connection of external devices, hasn’t been disclosed yet. However, the new standard requirements will be based on the SFF-8470 (Small Form Factor 8470) specification, which has been developed and applied for InfiniBand and Fibre Channel solutions. By the way, similar solutions were developed and will be implemented for more serious and demanding Serial Attached SCSI standard. In this respect, I would call the external SerialATA devices support a preliminary set of questions set and solved for the further use for Serial Attached SCSI standard.

According to the info, which has already been submitted by Comax Technology Company, which produces cables and also works on the standard, the requirements to SerialATA cables look as follows:

	Channel bandwidth	Max cable length
1 channel	1.5Gbit/sec	Less than 1m
2/4 channels	3Gbit/sec	1m
1 external channel	1.5Gbit/sec	2m
Several external channels	According to SFF-8470 specifications (not revealed yet)

Although, there is no problem at all with the production technology for cables intended for external SATA devices. Despite high standard requirements, you can already see a few types of such cables on Comax Technology site. And the company guarantees that its products cab ensure up to 4.5Gbit/sec bandwidth.

Unfortunately, unlike a more flexible USB standard, external SATA cables are purely informational interfaces, the drives will be powered separately, which is not determined by the standard. All the other interesting stuff, including the first samples of the new standard could be seen during the IDF Spring 2004.