There is a technical term for this problem: a forehead flattener.  i.e.,
when you take the palm of your hand and slap it upward against your
forehead.  Duh.

I was at the Sparc openboot prompt and typed "boot disk" and NetBSD booted
up without a problem.  I checked the devalias table and the open boot
environment and discovered that openboot had been configured to start
from "disk1" which was defined as sd@3,0 -- and that "disk" was defined
as sd@1,0.

joerch had suggested looking at the openboot environment and I had done
so -- but completely missed the definition of disk and disk 1 in the
devalias table and how it interacted with the boot device defined in
the openboot environment.

I changed the boot device to "disk" and reset.

Problem solved.

Now the fun part begins: I can get on with configuring the system.

My sincere thanks to all who provided help, suggestions and moral
support.   I am sure I will have more questions later.

Regards,
Will
The Old Bear