On Fri, Oct 22, 1999 at 10:51:27AM -0500, Kent Polk wrote:
> [This message has also been posted.]
> On 18 Oct 1999 23:15:00 -0500, Thor Lancelot Simon wrote:
> >On Mon, Oct 18, 1999 at 09:16:06PM +0000, Kent Polk wrote:
> >> On 17 Oct 1999 12:55:00 -0500, Tom Javen wrote:
> >> >
> >> >I got the same problem here with 20G IBM , seems that my motherboard (asus
> >> >p5a) with acer chipset has some problems on ultra dma .
> >> 
> >> Same here with a Quantum Fireball except it appears to work fine once it
> >> downshifts:
> >
> >Of course it does -- "DMA mode 2" doesn't have checksums, so there's no
> >way to know if your data's being corrupted or not!
> >
> >The logical thing to do is probably to downshift to UDMA mode 1 first.
> 
> It was suggested that I first try using a UDMA66 cable with the
> above drive. I installed one (on a short leash and with no other
> device on the cable) and absolutely nothing changed.  I have a
> hard time believing this is an electrical problem.

Well, believe what you like -- but an UDMA66 cable plugged into a non
UDMA66 IDE controller will do you no good, since there is no reason to
expect the extra pins to be grounded.

Have you tried telling it to use UDMA mode 1?  It's faster than "DMA
mode 2" anyway and you actually get the checksums, so you'll know if
something is Wrong.

It is hard to describe just how horrific the IDE electrical 
specification is.

-- 
Thor Lancelot Simon	                                      tls@rek.tjls.com
	"And where do all these highways go, now that we are free?"