[rescue] wide drive in an LX?

Sheldon T. Hall shel at artell.net
Tue Jan 1 05:34:40 CST 2008

Quoth Curious George ...
> I'd like to replace the 4G half-height drive
> in my LX with an 18G third-height drive that
> I have "collecting dust".
> The 4G is a SE narrow drive, as expected.
> The 18G is a SE *wide* drive.
> The LX, of course, expects SE narrow.
> I think I have a short 50-pin ribbon to
> 68 pin SCSI D cable that I pilfered off
> of some other piece of Sun kit (possibly
> to attach a CD-ROM to a wide SCSI bus?)
> The cable has a 68pin connector (male) on
> one end and a 50 pin terminator on the other.
> Adjacent to the terminator is a 50 pin ribbon
> (female) connector.
> I.e., if I cut off the terminator, I have
> the cable that I need.
> However, this means the drive end of the
> cable is unterminated (since the wide drive
> does not have on-board termination like
> the narrow drives do).
> I can strap the drive to force it to
> operate in SE mode (vs. LVD).  But, how
> will operating it without a terminator
> on that end of the cable work?  Likewise,
> since there are only 50 conductors coming
> across the cable, the high bits of the bus
> are unconnected and, thus, "floating".
> Will this be a source of problems?
> (I know I will have to ensure the drive
> is strapped for ID < 8 else it will never
> be selected  :>  )
> Or, am I worrying too much about nothing?
> Is the LX slow enough (rise times) that
> termination on such a short cable will be
> insignificant (I suspect the cable is about
> 12 inches long and there can't be more than
> another couple of inches on the LX plus the
> drive itself)?
> I'd prefer not to take the "try it and see"
> approach -- any more than I'd be happy 
> driving across country in a vehicle of
> dubious integrity!  :>
> Any other things to be wary of?  (besides
> boot partition in the first 2G of the drive)

I don't have a complete answer to your question, but I have an LX back home
with an SCA drive in it, with an adaptor but no terminator, and it works
fine.  I had to hack the sheetmetal drive mounting quite a bit, since the
drive + adaptor + cable connector was too long to fit into the normal drive
bay, of course, but it wasn't too hard.  I'd say the cable is less than a
foot long.


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