[pups] booting RT11 from alternate controller

[pups] booting RT11 from alternate controller

[Jonathan Engdahl]

I have a PDP-11/53 with a SCSI controller at 172150, and an RQDX3 at 172144.
There are a couple SCSI drives on the primary controller, and an RX50 on the
RQDX3. Everything seems to work OK, and I can read the floppies, except I
cannot boot RT11 from a floppy. From the 11/53 boot ROM you can say

B/A DU0

It will then ask for the address of the alternate controller. It reads from
the floppy, then it reads from both hard drives, then hangs.

What I hunch is happening is that the boot ROM reads the RT11 boot sector
from the floppy, but then the boot sector tries to continue booting from the
hard drives, which isn't going to work, because they are 2.11BSD formatted.

The objective is to have some non-RQDX3 hard drive controller as the
primary, and a secondary RQDX3 for the floppy, and to be able to boot UNIX
from the hard drive, and RT11 from the floopy. Any ideas on how to
accomplish this?

--
Jonathan Engdahl
http://users.safeaccess.com/engdahl

"The things which are seen are temporary,
 but the things which are not seen are eternal."  II Cor. 4:18

[pups] booting RT11 from alternate controller

[Jonathan Engdahl]

I'll have to try this with the RQDX3 as primary and the SCSI as secondary.
Maybe BSD is smart enough to do it right. In any case, I have the source for
the BSD boot code, and I can fix it. It will be a pain, though, having to
type the alternate address every time I boot BSD. I'd probably have to
restructure /dev and /etc/fstab also, and who knows what else. Maybe it
would be easier to change the jumpers if I needed to run RT11. I don't use
RT11 that much, but I'd like to have it available.

--
Jonathan Engdahl
http://users.safeaccess.com/engdahl

"The things which are seen are temporary,
 but the things which are not seen are eternal."  II Cor. 4:18


----- Original Message -----
From: "Fred N. van Kempen" <Fred.van.Kempen@microwalt.nl>
To: "Jonathan Engdahl" <j.r.engdahl at adelphia.net>
Sent: Wednesday, April 02, 2003 5:58 AM
Subject: RE: [pups] booting RT11 from alternate controller


Jonathan,

> I have a PDP-11/53 with a SCSI controller at 172150, and an
> RQDX3 at 172144.
This works for the ROM, but most PDP-11 operating systems will
refuse to boot from anything but the "default" controller of
any kind, meaning, an MSCP controller it will only accept at
172150.  The OS itself can deal with them, but not so for the
boot-level code that loads them.

I have tried similar setups with an 11/83 using an ESDI disk
controller at MSCP #0 (doing KDA50 emu), and an RQDX3 at
MSCP #1 (just for the floppies, indeed) and that didnt work
either, with RT11, MicroRSX and Ultrix.

--f