Messages in this thread |  | | Subject | Re: UDMA 133 on a 40 pin cable | From | Alan Cox <> | Date | 02 Jan 2003 23:24:07 +0000 |
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On Thu, 2003-01-02 at 22:00, Lionel Bouton wrote: > I'm wondering some things about IDE 40/80 pin cables since some time ago : > - somehow the circuitry can make the difference between 40 and 80 pin > (probably some pins are shorted or not by the cables or some > cable-type-dependent impedance between wires is mesured) and set a bit > for us to use. > - most probably the same circuitry can't verify the length of the cables > or their overall quality but I'm unsure. > > #1 How is the 40/80 pin detection done at the hardware level ? > #2 Are there any other cable-quality hardware tests done by the chipsets > ? How ?
Oh god. Andre described this one as needing a "two beer" explanation. I'd recommend stronger drinks however.
> I've encountered a barebone design (Mocha P4, uses 2.5" drives) where > the IDE cable was 40-pin but : > - has a single drive connector instead of the common two, > - its length is only around 10 or 15 cm. > A buyer contacted me for SiS IDE driver directions on this platform and > confirmed this at least for his purchase. > > #3 Is the above cable electrically able to sustain 66+ UDMA transfers > (could I hack a driver in order to bypass the 80pin cable detection and > make it work properly) ?
It is possible to do this yes. Other vendors do it as well. Careful cable choice lets you meet the electrical requirements other ways in certain situations.
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