SYSRUTH@utorphys.BITNET (02/18/88)
I seriously doubt if a unit number of 100 is supported by the proms and
drivers. It should not be difficult to change the unit number on the disk,
though - just a matter of setting a couple of switches at the back of the
drive (unless RA81's are radically different from most other disks, which
actually wouldn't surprise me). Of course everything has to be shut off
while you are doing this.
When you say the unit number was "chosen" do you mean someone there picked
it, or that it came that way from the factory? Most drives I have seen
only have two or three dip bits for the unit number so you can only
select units of 0-7. And how did you manage to format the disk?
If you set the unit number to anything reasonable, the uVAX proms will
find it and boot off it automatically. I would expect DUA3: to be the
highest number. It will even boot off DUBn: if the CSR on the board happens
to be set for the second controller. All the uVAX does is look for the first
DU-type disk with SYSBOOT.EXE on it.
One thing you could try, which at least you don't mention having tried
already, is the command
>>> b dua100 (***NO colon!!)
which is probably your only hope (it is entirely possible that just using
dua by itself defaults to a unit of 0, regardless of the current value of
R3). However if the machine won't boot off it all by itself, you don't want
to leave it that way or it will never be able to do an automatic reboot after
a crash or powerfail.
Hope this helps.
Ruth Milner
Systems Manager
University of Toronto Physicsrrk@byuvax.bitnet (02/26/88)
To change the unit number of the RA81, you have to pull out the button that
has the drive number and replace it with a button with a lower drive number
This sounds ridiculous, but it is true. The plastic pins on the back of the
button tell the drive what number be. Each pin is a binary digit. You
can cut off pins to make a low number into a high number, but it would probably
be futile to try to glue pins back on. Ask around to see if anyone has
a spare button. DEC probably has them all over the place.
Ray Whitmer