Re: hardware question: scsi disk and SS10

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> If the internal SS10 connectors have termination, this one is going
> to cause an additional problem.

I don't think the internal connectors per se have termination.

On a bus like SCSI, you really want no termination anywhere except at
each end, where the bus should be terminated with the characteristic
impedance of the bus lines, to avoid signal reflections off the end of
the bus.

You can sometimes get away with playing fast and loose with
termination, especially if the bus is short and devices are operating
at low speeds (because then reflections die down fast enough to not
cause trouble).  But sometimes you can't, too.

> Are the two attachments equivalent?  is tehre any preference in your
> experience?

I don't have enough experience with internal drives on '10s to say
anything useful here.  I don't have very many '10s and I try to avoid
using internal drives in the pizza-box machines for heat dissipation
reasons (most of my use cases are willing to tolerate an additional fan
and an additional power supply's losses in order to extend the useful
life of the equipment).

> On the net there are reports where if the hard-disk is not properly
> formatted/partitioned probe-scsi will fail to detect it, but I think
> these are misleading.

I don't think I've seen that.  It's certainly possible that if it's
formatted with other than 512 bytes per sector, the ROM code refuses to
acknowledge its existence - I haven't tried enough non-512-byte drives
to have any data on that - but I definitely have used disks without a
Sun label on them.  (On SPARCs in general, that is; I don't
specifically recall a SS10 working that way, though I'd be surprised if
it misbehaved.)

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