Messages in this thread | | | Date | Fri, 3 Jan 2003 02:29:37 -0800 (PST) | From | Andre Hedrick <> | Subject | Re: IDE termination (was Re: UDMA 133 on a 40 pin cable) |
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On Fri, 3 Jan 2003, John Bradford wrote:
> > > I don't think ATA66+ controllers can be within spec if they don't detect > > > 40 vs 80 pin cables. > > > > I wish. Alas not in the real world. > > Something that occurs to me, which is somewhat related to this: > > My understanding, (which might be wrong) is that termination of the > IDE bus is partly handled by each connected devicem rather like modern > floppy drives, (in contrast to SCSI, 10-base-2, old floppy drives etc, > where the termination is handled by devices at the physical ends of > the cable). > > So if you connnect a really old IDE disk, say a 20 Mb one, and an > ATA-100 one to the same bus, is the termination then out of spec, > (analogous to using passive terminators on anything other than a SCSI-1 > bus), because presumably the termination requirements are stricter for > the higher bus speed and signaling on both edges?
All are self terminating, and are effected by the M:S:C jumpers for their responses. Things like leak current times and other events that are based on various decay rates against an assumed Z value for a given ribbon+devices+host combination will change things rudely.
There are issues of shadow registers and pattern responses.
But you got the swing of it!
Cheers,
Andre Hedrick LAD Storage Consulting Group
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