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Re: cheapest SX System i ever have seen

Ross A. Knepper wrote:

> > > >Hard Disk 2.xx GB  IDEE
> > > >CD-ROM 16-24 speed IDE
> >
> > > 6.4Gb ST36450A, 9.5ms, 5400rpm, 3.5" FH
> > > 32x Toshiba IDE CD-Rom Drive
> >
> > >From what i hear, IDE is a horrible thing to inflict upon an Alpha,
> > because they use such a pathetic controller.
> > (I've heard of reports that IDE drives run so slowly that you'd
> > think you're on a 386)
> from what i understand, the IDE controller in the PC164, etc. (CMD646) is
> actually a decent device.  the problem is that because the prior version
> (the CMD640) was buggy and slow, nobody ever bothered to develop the
> driver for the 646 very far.  it's another case of "if only somebody would
> write the [better] driver for it" ...
> i would be willing to give it a go, if only i knew the first thing about
> IDE or the CMD ...
> can anybody confirm my hunches about this controller?  if so, can anybody
> point me toward online documentation for these things so that might toy
> around with it and see what i can do? (ah, the ignorance of youth ...)
>  -ross


You're correct about the CMD646. Linux does not have a decent driver
for it. Check the 2.1.xx series for their IDE drivers. Last I heard it was
being worked on there. What you need is the DMA bus master docs
that describe how to use the chip in DMA mode instead of PIO mode,
which is what the current Linux driver does (it uses generic code that
doesn't appear to be optimized for any one type of chip set). If you
don't clearly understand what I just said, I suggest you not try modifying
things unless you don't mind trashing your disks. (screw ups in that
arena can be painful)  Kai Schultz did some mods to the 2.1.xx drivers
too that helped PIO mode. Check in the axp-list archives back about
6 months and it should be there.


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