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On Wed, Dec 15, 2010 at 11:35 AM, Grant Edwards |
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<grant.b.edwards@×××××.com> wrote: |
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> On 2010-12-15, Andrea Conti <alyf@××××.net> wrote: |
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>>> E-SATA != SATA !!!! |
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>> |
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>> Nah. They are *exactly* the same. |
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> |
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> Not according to Wikipedia -- it says the electrical specs for eSATA |
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> are different than the specs for "normal" SATA. I've seen that stated |
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> in other places as well. I don't have copies of the two specs, so I |
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> can't say I'm 100%, but I believe the Wikipedia page. |
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> |
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It is true, and has to be for cost reasons. |
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1) Internal SATA drives are at the end of a single cable and don't |
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require hot-plugging logic be built into the SATA port driver on the |
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SATA controller because they are always powered up. (They are inside |
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the case) |
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2) External SATA drives are at the end of 1) an internal cable, 2) a |
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case SATA-eSATA connector, and 3) an external eSATA cable along with |
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whatever is inside the eSATA case. eSATA compatible ports must include |
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hot-plugging logic. |
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For cost/simplicity reasons chip manufacturers are free to remove |
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hot-plugging logic from any port for which they don't intend eSATA |
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compatibility. |
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The logic and timing of the signals on SATA and eSATA cables is |
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(TTBOMK) intended to be identical. What those signals look like at |
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different places in the cable chain will be different. |
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- Mark |
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