updated 10:35 am EDT, Thu August 21, 2008
Apple eSATA Patent
Apple has been exploring the possibility of adding external Serial ATA (eSATA) to its Mac lineup through a unique method, the company has revealed through a newly published patent filing. The application both references adding the format to a computer for outside storage but also the possibility of an outside computer accessing this storage through a switching mechanism; holding a key on startup or toggling a hardware control on the host computer would start up a low-power mode that makes its internal storage available as though it were external drive attached to the other system.
The method described closely resembles Apple's own Firewire Target Disk Mode, which was developed to speed up data transfer between two local Macs and more recently has been used to ease copying data to a new Mac through Apple's Migration Assistant feature. Apple notes in its filing that eSATA has no built-in spec of its own to handle this kind of behavior.
It's unclear whether Apple intends to use the technology from the patent for shipping products. The technique was first proposed in February of last year but hasn't been used for any existing Mac, all of which have at most been able to use FireWire 800. The external SATA format has been valued by ASUS and several other PC makers for performing in identical fashion to internal SATA, which in its base form transfers is theoretically almost twice as quick at a peak speed of 1,500Mbps.
Recently, the IEEE approved the FireWire 3200 specification, a variant of the Apple co-developed format that would outperform eSATA at about 3,200Mbps.