Re[2]: SCSI ID vs. unit ID

The external connector on the back of the 150 can drive
an additional tape drive with active LVD terminator,
if you are lucky. Some combinations work, some dont.
You might want to test a DDS3 drive with Adapter to 50pin SCSI,
as well as some old LTO1 drives ;-)
For external disk, the Bus might not work well, you might
try 6 disks by using SCSI ID 6, 5, 4, 3 and 8, 9
(no guarantee).

There is no direct mapping between SCSI ID and Unit ID, as this is
defined per model (or: per system case for 150, 170, 600, etc)
If you mount a device which is not „planned“ by IBM, SST
might show as „unresolved location“, but it can work…

170 is much more fun to play with, as Larry pointed out :)
It also has an external connector to be used with the internal
bus, but as 170 does support RAID cards with multiple
SCSI buses, you can connect external SCSI devices by
simple adapter cables.

-h


------ Originalnachricht ------
Von: "Patrik Schindler" <poc@xxxxxxxxxx>
An: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxxxxxxxx>
Gesendet: 17.01.2022 16:05:09
Betreff: Re: SCSI ID vs. unit ID

The 150 has a stock 68 Pin "external" HD connector hidden behind a metal coverage, just above the PSU. Problem is after the external connector, the cable runs 2 cm to its real end, to a permanently attached bus terminator. I have not yet found out how automatic SCSI bus termination really works, to verify if that thing can switch itself off magically. At the same time, I highly doubt that said bus terminator is automatic: The connector is normally hidden, and thus more likely another "debug" port, to attach a *short* cable to a logic analyzer or so.