From: plica2006@gmail.com

I think I have figured out what was happening here.

The device name (DUAx vs DJAx) assigned to the ISO file depends on what
SIMH version you are using:

SIMH v4.0-0 maintained by Mark Pizzolato:
https://github.com/simh/simh

Open SIMH v4.1-0
https://github.com/open-simh/simh

If your ISO file is small enough in size then with SIMH v4.0-0 (Mark
Pizzolato) you might get the device name: DJA1.

In my case I am trying to restore the save_set from an ISO of OpenVMS
v5.5-4H2.

Because the ISO is only about 204MB SIMH uses its internal logic
(autosize) to assign the ISO file a device type of RA60 because that is
the closest DEC device capacity drive that 204MB matches with. This is
what happens regardless if you start out with this in your ini file:

SET RQ3 CDROM
ATTACH RQ3 -r openvms_v5.5-4h2.iso

So SIMHv4.0-0 responds to a MRSP query from Standalone Backup with a
deviceID: (DJ - RA60) indicating that the device at that controller is
a removable device of type RA60. (DJ - Removable, DU Fixed). Standalone
Backup then uses it's own logic to translate this to a device name
DJA3.

If you disable AUTOSIZE then you will get DUA3 as the device name:
set rq3 cdrom
set rq3 NOAUTOSIZE
attach rq3 -r openvms_v5.5-4h2.iso

This is because SIMH v4.0-0 will now just respond to a MRSP query with
whatever device type you define in your ini file.

If you use Open SIMH v4.1-0 you will probably just get DUA3 as the
device name and not have to disable AUTOSIZE at all. I don't fully
understand how SIMH and Open SIMH differ in their device detection
logic but it seems that with Open SIMH if you put this in your ini
file:

SET RQ3 CDROM
ATTACH RQ3 -r openvms_v5.5-4h2.iso

Then Open SIMH WILL respond to an MRSP query that the device type is
CDROM and then Standalone Backup will see this as an RRD40 device and
create the device name DUA3.

CDROM device are also removable drives but whereas RA60 disks were
connected to MSCP controllers RRD40 disks were connected to DSA
controllers where any type of local disk were consolidated under DUAx
device naming. Not confusing at all!
 
Cheers,

Flex

-----Original Message-----
From: Sam Thomas 
Subject: Re: SIMH + OpenVMS 5.5-2H4 standalone BACKUP: ISO appears as
DJAx not DUAx
Date: 18/12/25 17:05:41
Newsgroups: comp.os.vms

flexmcmurphy  wrote:
> Hello,
> 
> I am installing OpenVMS VAX 5.5-2H4 under SIMH and am confused by
> how  
> standalone BACKUP assigns device names when booted from installation
> media.
> 
> This is where I got the ISO from (Server 1)  
> 
> Setup (simplified):  
> - SIMH VAX (have tried MicroVAX 3900 and VAX 8600)  
> - OpenVMS VAX 5.5-2H4 ISO attached as an RQ device (read-only)  
> - Booting directly from the ISO into standalone BACKUP
> 
> In standalone BACKUP, the installation media always appears as DJAx  
> (device type RA60), not as DUAx, for example:
> 
> Available device DJA3: device type RA60

Without seeing your setup, I can't tell you exactly why yours
results in DJA, but here is the relevant parts of the config I
used to do this exact thing. I don't remember exactly where
I got the base of my vax.ini, but it was one of the top
google results. 

set rq0 rauser=8192
set rq1 rauser=8192
### I suspect this is the bit you might be missing?
; Configure a CD-ROM drive (RRD40) on disk interface RQ3
set rq3 cdrom
attach RQ0 /home/sthomas/vax/oldvax/data/rq0-big.dsk
attach RQ1 /home/sthomas/vax/oldvax/data/rq1.dsk
attach RQ3 -r /home/sthomas/vax/oldvax/iso/VMS55.iso

Cheers,
Sam

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