Re: UDMA 133 on a 40 pin cable

Ross Biro (rossb@google.com)
Thu, 02 Jan 2003 14:40:20 -0800


>
> #1 How is the 40/80 pin detection done at the hardware level ?

On the motherboard end of the 80 conductor cable, the connector shorts
one of the pins to ground (maybe pin 38). The ide controller just
checks to see if the pin is pulled low or not. Pulled low = 80 pin.
That's one of the reasons it's important to plug IDE cables in the
correct way.

Ross

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