Thanks for all the replies.  My 918LX uses the pedestrian single ended
SCSI interface for its one and only disk currently installed.  My
space woes were somewhat abated through some aggressive inspection of
what is actually stored on our disk; I located some files left over from
MPE 5.5 which were supposed to have been deleted as part of the upgrade
process to 6.0, as well as some (MPE equivalent of) tar files containing
a previous version of the billing APP running on said machine.

The anecdotal evidence seems to indicate I can use the less expensive non-HP
firmware ST34573N drives.  I can appreciate the need for HP firmware on
some of the more modern SCSI busses in more advanced configurations but
will assume (hopefully correctly) that single ended SCSI technology has
stabilized on both the HP and 3rd party ends.

The sysgen examples were also helpful, to sharpen up my MPE/IX skills.

Thanks again
Paul

In article <[log in to unmask]>,
        Steve Dirickson <[log in to unmask]> writes:
>> The Seagate drives ending in "LW" can be connected (via a
>> simple adapter)
>> to the standard Single Ended SCSI on a "standard" HP 3000.
>> (We have such a one
>> installed, the adapter is inside the external case we put the
>> drive in.)
>> (This conversion is possible because Low Voltage Differential is
> quite
>> a different beast than the older "Differential")
>
> As can any non-differential "W" model. For best results, use device
> converters; if you use a cable converter, make sure you buy quality
> 68-to-50-pin converters that terminate the upper conductors.
>
>> There may be other interfaces that can be connected via adapters...
>> but don't ask *me*!  (I dimly recall trying to convert an LC (SCA)
>> with no success...but I'm not sure that's what it was.)
>
> That works too; SCA drives can be attached to 50- or 68-conductor
> cabling with adapters. However, the adapters I've seen don't have any
> retention devices to keep them firmly plugged into the drive, so I'd
> hesitate to use them in critical application (which is why the 3 I
> have are in my 3rd-string box; if it goes down, nothing is lost).
>
> And there are adapters to connect Differential devices to SE busses
> and vice versa. It seems that pretty much any kind of SCSI device can
> be connected to any other with the appropriate intermediary hardware.
>
>> If you have a F/W Differential SCSI card, then you can use the
>> drives ending in WD.  I don't know anything about using other
>> interfaces, however.
>
> Or "D" drives, with a 68/50 device converter.
>
>> I used to recommend buying cases (for external drives) from Granite
>> Digital, but they now use the same cheap ones that everyone seems
>> to use :(   (I'd like to find a better made case, with better fans,
>> but under $150))
>
> http://www.ci-design.com
>
>
> Steve Dirickson   WestWin Consulting
> [log in to unmask]   (360) 598-6111
>

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