10 Sep
2012
10 Sep
'12
8:47 a.m.
On Sep 10, 2012, at 11:38 AM, Dave McGuire wrote:
On 09/10/2012 10:25 AM, Mouse wrote:
Me neither. The definition of "need" here is that, electrically, they
are required by the design, but the designers, either due to cheapness,
cluelessness, or both, omitted them.
It's probably worth clarifying that the ANSI spec calls for termination
(not necessarily discrete terminators). One ordinarily needs discrete
terminators, or an on-drive workalike as implemented in many SCSI drives,
in a bus because you don't want every device providing termination
(besides dragging down the bus, you'll still be throwing the impedance
off and so will get reflections anyway). In practice, most ATA cables
are short enough that it almost doesn't matter because the standard only
supports two drives per cable; SCSI is, obviously, a very different case.
- Dave
[IDE]
actually DID need terminators...
I'm not sure what meaning of "need" this is, when, out of all the
IDE-using systems I've seen, I can't recall even one that had
terminators.