Messages in this thread |  | | Date | Thu, 02 Jan 2003 23:00:56 +0100 | From | Lionel Bouton <> | Subject | Re: UDMA 133 on a 40 pin cable |
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Happy new year everybody
Alan Cox wrote:
>It got CRC errors, not suprisingly and will drop back. Nevertheless it >shouldnt have gotten this wrong, so more info would be good. > >
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 ?
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) ? #4 Are the electrical specs for 66+ UDMA transfers public (couldn't find by googling) ? Where can we find them ? Here I mean some really basic specs (max Resistance/Capacity/Inductance between wires, max signal propagation delays and so on) and not general high level specs (material, connector design, length ranges allowed in the general 80-pin, 2 drives case).
Any hints on these Andre ?
LB.
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