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Re: OT broken SCSI termination WAS Re: ahc still being broken
<snip my crap>
> In 20 some odd years of working on computer systems I have seen broken
> SCSI H/W implementations where removing the terminators actually 'caused a
> device to work properly. I didn't believe it either until an NEC tech
> support dude once told me to REMOVE the termination after an NEC CD-ROM
> that was at one end of the SCSI chain. I didn't believe it would work,
> but it did. When I asked him for specifics he kinda hemm'd and haw'd
> before he admitted that NEC had a known "feature" in their SCSI
> implementation for this CD-ROM drive.
Sure that'll work...for 8 bit 10 (maybe 20) MHz devices. But if you add some
16 bit U160 (80MHz) DT devices to the chain it will fail miserably. Without
termination the P lines which are used to clock the data will "blur".
I have done quite a few of these one-offs and it worked mostly. But as soon as
different speed devices are on a bus it usually doesn't.