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Brad Thompson wrote:
> 
>         [ ... invisible 2nd HD for Personal DS ... ]
> 
> > The machine in question now had two RZ25 drives, a 25MHz CPU, and 40M
> > of RAM (8M onboard and 4 8M SIMMs).  When the machine is powered
> > on and I run cnfg 3, I get:
> >                 ...
> >                 DEV   PID                VID        REV    SCSI DEV
> >                 ===== ================== ========== ====== ========
> >                 rz1   RZ25     (C) DEC   DEC        0A00   DIR
> >                 rz2   RZ25     (C) DEC   DEC        0900   DIR
> 
> [ ... but rz1 can not be probed correctly by NetBSD/pmax kernel ... ]

Why is NetBSD/pmax not able to probe rz1 ??

> 
> > Does anyone have any idea
> > what might be causing the second drive to not show up?
> 
> Missing SCSI termination?
> 
> All of three my PDS configurations with single drive never have
> SCSI terminating register packs, however, dual drive configuration
> might be electorically sensitive in that subject.
> 
> Tohru Nishimura

One problem of the PDS is, that the internal hard drives are connected
via a short cable to the SCSI bus. Layout can be described as follows:

-----------\---------------------------\------------------------ SCSI 50
wire
---------\--\------------------------\--\----------------------- bus
          | |<-- short 50-pin cable   | |<-- short 50-pin cable
          | |    (less than 5 cm)     | |    (less than 5 cm)
          / /                        / /
        +----+                     +----+
        |HDD1|                     |HDD2|
        +----+                     +----+

This means, that the HDD 50 pin connector is not connected to the SCSI
bus directly, but uses a connection cable instead. AFAIK the SCSI specs
say this is permitted as long as the extra connection cable an the drive
internal wires are less than 10 cm long.

One should be aware than any other setting might not work as expected.

I on my PDS have them set up with two internal drives, but installed the
second in the DEC specifing mounting assembly (which may be taken off by
simply removing a mounting spring, they are U-shaped). This assembly
fits into the mounting holes in  the cassis near the second SCSI
connector you mentioned. Then the connection cable may be very short.
You have to use a much longer SCSI connection cable which might prevent
the HDD to work when used.

On the other hand, when you have NetBSD running try to read the disk
with dd or something similar. This will show you, if the drive is
operating ...
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